Dissertations / Theses: 'Virus à transmission verticale'

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BORTUZZO, THIERRY. "Etude de la transmission verticale du virus de l'hepatite c." Clermont-Ferrand 1, 1993. http://www.theses.fr/1993CLF1MS23.

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Gautier-Charpentier, Lucile. "Diagnostic et transmission verticale du virus de l'immunodéficience humaine au Burkina Faso : influence de la diversité du virus." Tours, 2001. http://www.theses.fr/2001TOUR3804.

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Le virus de l'immunodéficience humaine (VIH) est caractérisé par une grande diversité génétique. Deux types de virus ont été identifiés : les VIH-1 et 2. Au Burkina Faso, pays où se situe notre étude, aucune description de la diversité des souches circulantes n'a été entreprise. Nos objectifs étaient d'évaluer l'influence des sous-types du VIH-1 sur le sérodiagnostic de l'infection et sur la transmission du virus de la mère à l'enfant. Les outils utilisés pour décrypter la diversité du VIH-1 étaient un test de sérotypage par compétition de peptides en phase liquide et la technique génétique de mobilité des hétéroduplexes (HMA). Une évaluation de tests commerciaux de sérodiagnostic de l'infection par le VIH a été réalisée au Burkina Faso afin de proposer une stratégie nationale simple, fiable et peu onéreuse. Le sérotypage des échantillons positifs aux tests ELISA évalués dans cette étude a montré que les réponses en densité optique aux tests ELISA étaient très élevées quel que soit le sérotype du VIH infectant. Une surveillance répétée de la fiabilité des tests utilisés en fonction de l'introduction des nouvelles souches de VIH a été recommandée. Un essai clinique évaluant la tolérance à la zidovudine et au chlorure de benzalkonium chez des femmes enceintes infectées par le VIH-1, a été réalisé. Des souches de génotype A et G ont été identifiées par HMA. Ces résultats suggèrent que la technique de sérotypage utilisée n'est pas un outil contributif pour le sous-typage du VIH-1 au Burkina Faso. Les résultats du suivi biologique des mères et de leurs enfants ont montré que les génotypes A et G ne sont pas des déterminants de la transmission verticale du VIH-1, d'un taux bas de lymphocytes CD4 maternels, ni d'une charge virale maternelle élevée. La réalisation de ce type d'étude dans des pays où d'autres sous-types sont prédominants a été recommandée, afin d'avoir une vision plus large de l'influence des sous-types du VIH-1 sur la transmission verticale du virus.

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Vazeille, Marie-Christine. "Etude de quelques virus de dipteres comme modele pour la transmission verticale des arbovirus chez les insectes." Clermont-Ferrand 2, 1987. http://www.theses.fr/1987CLF21064.

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Vazeille, Marie-Christine. "Etude de quelques virus de diptères comme modèle pour la transmission verticale des arbovirus chez les insectes." Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37610550h.

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Moussa, Marlène. "Cytokines et chimiokines placentaires et transmission materno-foetale du virus de l'immunodéficience humaine de type 1." Paris 11, 2000. http://www.theses.fr/2000PA11T019.

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La grossesse réussie implique une adaptation du système immunitaire maternel à la présence du fœtus, qui peut être considéré, au niveau immunologique, comme une semi-allogreffe. La tolérance de la mère nécessite une immunosuppression locale, à laquelle participe fortement le réseau cytokinique placentaire et utérin. Nous avons étudié les cytokines et chimiokines présentes à l'interface placentaire du premier trimestre et de fin de grossesse humaine. Les composants majoritaire de l’environnement cytokinique placentaire sont, dans notre système d'étude, les chimiokines MIP-lα, MIP-1,1β, RANTES et IL-8, ainsi que les cytokines inflammatoires IL-lβ, IL-6 et TNF-α, et que les facteurs de croissance GM-CSF et CSF-1. Par contre, contrairement à l'hypothèse avancée en 1993, que la grossesse réussie nécessitait un profil de cytokines locales de type 2, nous n'avons pas mis en évidence de sécrétion significative de ces cytokines par les villosités placentaires. Des différences quantitatives existent entre les cytokines produites par le placenta du premier trimestre et le placenta de fin de grossesse, qui pourraient correspondre à des modifications des fonctions métaboliques, hormonales et invasives du placenta. La transmission materno-fœtale du VIH peut avoir lieu in utero et impliquer le passage du virus à travers la barrière placentaire. Pensant que le microenvironnement placentaire pouvait jouer un rôle régulateur de ce passage, nous avons comparé les profils d’expression des différentés cytokines et chimiokines entre les villosités placentaires de mères séropositives pour le Vlll et de mères séronégatives. Nous n'avons pas pu mettre en évidence de différence significative majeure dans la production des cytokines locales entre ces deux types de placentas. Cependant, la population trophoblastique, constituant la première couche cellulaire du placenta en contact avec le sang maternei, pourrait être capable de moduler ses sécrétions de cytokines inflammatoires et de chimiokines sous l'action du virus. Nous en concluons que des variations fines et locales pourraient entrer en jeu dans des processus autocrines impliquant les trophoblastes, et modulant peut-être leurs capacités invasives, métaboliques, ainsi que la réplication virale si ils sont infectés in vivo et la transmission du virus aux couches cellulaires placentaires plus internes
Pregnancy outcome is depending on the capacity of aptation of the maternal immune system to the presence of the semi-allogeneic fetus. Maternal tolerance is mediated, by part, by a local immunosuppression. Placental cytokines and microenvironment are essential components of this tolerance. We have studied the cytokines and chemokines spontaneously secreted by human placental villi and cells, from first trimester or end _of pregnancy. We found expression of chemokines (MIP- Lα. , MIP-lβ, RANTES and IL-8), inflammatory ;cytokines (lL-I β, IL-6 and TNF-α. ), and growth factors (GM CSF and CSF-1). Surprising!y, we did not detect important secretion of any type 1 or type 2 cytokines. We could highlighted quantitative differences in the pattern of cytokines and chemokines expression between first trimester and term placentae, which could be related to variations in metabolic, hormonal and invasive functions. Mother-to-child HIV-1 transmission could occur in utero through the placental barrier. We hypothesized that placental microenvironment could influence mechanisms of placental viral transmission, and we compared cytokines and chemokines secretion profiles between term placentae from HIV-seropositive and HIV-seronegativewomen. No major difference could be seen at the level of placental tissue. However, it seems that the first cellular layer in contact with maternal blood (trophoblatic cells) may express differently intlammatory cytokines and chemokines depending on the HIV infection of the mother. Some local variations in cytokines and chemokines may act in an autocrine proccss on proliferative, invasive and hormonal functions of trophoblast, or on HIV replication and spreading in the placenta, if trophoblasts are infected in vivo

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Hahn, Tobias. "Characterization of human immunodeficiency virus type 1 associated with and without vertical transmission." Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/284331.

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Vertical transmission of human immunodeficiency virus type 1 (HIV-1) occurs at an estimated rate of 30% and accounts for 90% of all HIV-1 infections in children. Increased risk of vertical transmission correlates with advanced maternal disease status, low CD4+ lymphocyte count, and high viral load. However, the molecular mechanisms of vertical transmission are poorly understood, making it difficult to design effective strategies for prevention and treatment. Our hypothesis is that specific molecular and biological properties of HIV-1 are critical determinants of vertical transmission. We characterized the HIV-1 gag p17 matrix (MA) and nef genes associated with and without vertical transmission. In addition, we determined the effect of env gp120 from mother-infant pairs and from infected mothers who failed to transmit the virus to their infants (non-transmitting mothers) on HIV-1 replication, cellular tropism, cytopathic effects and co-receptor utilization. Our data indicate that the open reading frames and the functional domains of both the gag p17MA and nef genes were highly conserved in isolates from mothers and their infants. While there was no significant difference in the maintenance of open reading frames and the conservation of functional domains between isolates from transmitting and non-transmitting mothers, we found that the non-transmitting mothers' gag p17MA sequences were more homogenous compared with the transmitting mothers' sequences. In addition, we were able to associate several motifs in p17MA with either transmitting or non-transmitting status. To study the effect of gp120 on HIV-1 biology, we reciprocal inserted the gp120 from mother-infant pairs and non-transmitting mothers into a T-tropic infectious clone and found that the chimeras were unable to replicate in T-cell lines and did not form syncytia in MT-2 cells. Moreover, these chimeras used the CCR5 co-receptor for entry in the U373MAGI-CD4-CCR5 cell line. Both the mother-infant pairs' and the non-transmitting mothers' gp120 chimeras replicated well in primary peripheral blood lymphocytes (PBL) with no significant difference in replication kinetics. These results may be helpful in the understanding of the association of viral determinants and molecular mechanisms of vertical transmission, which may contribute towards the development of new strategies for treatment and prevention of HIV-1 infection in children.

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Kfutwah, Anfumbom Kitu Womeyi. "Effet du VIH-1 et de la prophylaxie de la transmission mère-enfant (TME) associés ou non à une co-infection palustre sur la balance des cytokines/chimiokines au sein de l'environnement placentaire." Paris 7, 2006. http://www.theses.fr/2006PA077115.

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LA TRANSMISSION MERE-ENFANT (TME) EST RESPONSABLE DE PLUS DE 90% DU NOMBRE D'ENFANTS INFECTES PAR LE VIH-1. LES ANTIRETROVIRAUX (ARV) ONT PERMIS DE REDUIRE EFFICACEMENT LA TME DU VIH-1 DANS LES PAYS DEVELOPPES. AVANT L'AN 2000, IL N'Y AVAIT PAS DE PROGRAMME DE PREVENTION DE LA TME DU VIH-1 AU CAMEROUN. LES OBJECTIFS PRINCIPAUX DE CETTE THESE ETAIENT DE CONTRIBUER A LA MISE EN PLACE D'UN PROGRAMME DE PREVENTION DE LA TME DU VIH-1 AU CAMEROUN EN UTILISANT LA NEVIRAPINE (NVP) ET D'ETUDIER DES FACTEURS ASSOCIES AU CONTROLE OU NON DE LA TME COMME L'ENVIRONNEMENT CYTOKINIQUE DU PLACENTA ET LES CONFECTIONS PALUSTRES. NOS RESULTATS INDIQUENT QUE LE TAUX DE TME DU VIH-1 AVEC LA NVP ETAIT DE 13% ET CECI DANS UN CONTEXTE DE FORTE DIVERSITE VIRALE ET DE FAIBLE RESISTANCE INITIALE DU VIH-1 AUX ARV (MOINS DE 5%). UNE VARIABILITE IMPORTANTE DES NIVEAUX DE CYTOKINES (ARNM ET SECRETION) ETAIT OBSERVEE DANS LES PLACENTAS DES FEMMES VIH-1 NEGATIVES ET POSITIVES. LORSQUE LES PARAMETRES CLINIQUES ETAIENT PRIS EN CONSIDERATION, DES DIFFERENCES SIGNIFICATIVES ETAIENT OBSERVEES ENTRE LES FEMMES VIH-1 NEGATIVES ET POSITIVES AVEC UNE PREDOMINANCE DU TNF-oc CHEZ LES POSITIVES. LA PARASITEMIE PALUSTRE ETAIT PLUS ELEVEE CHEZ LES FEMMES VIH-1 POSITIVES. NOS RESULTATS INDIQUENT EGALEMENT QUE LE PALUDISME MODULAIT L'ENVIRONNEMENT CYTOKINIQUE PLACENTAIRE. NOUS AVONS MONTRE EN PARALLELE QUE LE TNF-a, QUI EST ELEVE LORS DU PALUDISME, AUGMENTE LA REPLICATION VIRALE DANS DES HISTOCULTURES DE PLACENTAS INFECTES PAR LE VIH-1. CES RESULTATS CONFIRMENT L'EFFICACITE DE LA NVP POUR REDUIRE LA TME DU VIH-1. CEPENDANT LE PALUDISME POURRAIT DIMINUER CETTE EFFICACITE EN MODIFIANT LES PROFILS DE CYTOKINES PLACENTAIRES
More than 90% of hiv-1 infected children acquire the virus through mother-to-child transmission (mtct). Antiretroviral (arv) prophylaxis have greatly reduced mtct of hiv-1 in the developed world. Before 2000, no effective program on the prevention of mtct existed in cameroun. The main objectives of this thesis were to contribute in the initiation of a program on the prevention of hiv-1 mtct in cameroun using nevirapine (nvp) and to study factors associated with the control or not of mtct such as the placental cytokine profiles and malaria confections. We observed a 13% mtct of hiv-1 with nvp prophylaxis in a context of a large hiv-1 diversity in yaounde. Less than 5% of the pregnant women naïve of arv treatment presented resistant mutations to arv. A high variability was observed in the mrna expression and secretion of cytokines in the placentas of both hiv-1 negative and positive women. Analyses considering clinical parameters revealed significant differences between hiv-1 negative and positive women, with tnf-a predominating in the hiv-1 positive group. Malaria parasitemia was significantly higher among hiv-1 positive women. Malaria parasite was observed to greatly alter the placenta cytokine environment. We then showed in parallel that tnf-a, which is associated with malaria, enhanced viral replication on hiv-1 infected placental histocultures. Together, these results show that nvp is efficient in the prevention of hiv-1 mtct and that malaria could alter this efficiency by modulating the placental cytokine environment

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Delicio, Adriane Maira 1979. "Transmissão vertical do virus da imunodeficiencia humana em uma coorte de gestantes em Campinas entre 2000 e 2009." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/309588.

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Orientador: Helaine Maria Besteli Pires Milanez
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas
Made available in DSpace on 2018-08-14T07:08:24Z (GMT). No. of bitstreams: 1 Delicio_AdrianeMaira.pdf: 1826833 bytes, checksum: bc3f2dce3447c00fccb97f45337d0f78 (MD5) Previous issue date: 2009
Resumo: Objetivo: avaliar a transmissão vertical (TV) do HIV e fatores associados em gestantes soropositivas acompanhadas em um serviço universitário brasileiro (CAISM/UNICAMP) entre 2000 e 2009. Sujeitos e Métodos: coorte histórica de 452 gestações e seus recém-nascidos. Os dados foram coletados dos prontuários e registrados em fichas específicas. Crianças sem seguimento foram convocadas para definição diagnóstica. Análise dos dados: análise descritiva através de distribuição percentual e de médias; teste de X², exato de Fisher, t de Student, Mann-Whitney e ANOVA, razão de risco e intervalo de confiança. Resultados: A TV foi de 3,6%. A idade média das gestantes foi 27 anos; principal categoria de exposição foi a sexual (86,5%); 55% já apresentava o diagnóstico prévio à gravidez. Sessenta e dois por cento não estavam em uso de TARV ao engravidar. CD4 médio inicial foi de 474 células/ml e 70.3% apresentaram carga viral indetectável no terceiro trimestre. Como TARV, 55% usaram esquemas com IP e 35% com nevirapina. Monoterapia com AZT foi utilizada em 5,5%. Idade gestacional média no parto foi de 37,2 semanas e em 92% a via foi cesárea; 97,2% receberam AZT endovenoso. Os fatores associados à TV foram: baixa contagem de CD4, elevada carga viral, tempo reduzido de TARV, presença de alterações gestacionais (anemia, RCF, oligoâmnio), coinfecções durante o pré-natal (CMV e toxoplasmose) e presença de trabalho de parto. Uso de TARV potente, parto por cesárea e uso do AZT pelo RN foram fatores protetores. Má adesão ao tratamento esteve presente em 13 dos 15 casos infectados; em sete houve presença de coinfecção neonatal (CMV e toxoplasmose). Conclusão: Fatores de risco para TV foram comprometimento do estado imunológico da gestante, menor tempo de terapia, coinfecções (CMV e toxoplasmose) e presença de trabalho de parto. O uso de TARV potente e a realização de cesárea foram fatores protetores para a TV do HIV.
Abstract: Objectives: to evaluate mother-to-child transmission (MTCT) rates and related factors in HIV-infected pregnant women from CAISM/UNICAMP between 2000 and 2009. Subjects and methods: cohort of 452 HIV-infected pregnant women and their newborns. Data was collected from recorded files and undiagnosed children were enrolled for investigation. Statistical analysis: qui-square test, Fisher exact test, Student t test, Mann-Whitney test, ANOVA, risk ratio and confidence intervals. Results: MTCT occurred in 3.6%. The study population displayed a mean age of 27 years; 86.5% were found to have acquired HIV through sexual contact; 55% were aware of the diagnosis prior to the pregnancy; 62% were not using HAART. Mean CD4 cell-count was 474 cells/ml and 70.3% had undetectable viral loads in the third trimester. HAART included nevirapine in 35% of cases and protease inhibitors in 55%; Zidovudine monotherapy was used in 5.5%. Mean gestational age at delivery was 37.2 weeks and in 92% by caesarian section; 97.2% received intravenous zidovudine. Implicated factors related to MTCT were: low CD4 cell counts, elevated viral loads, maternal aids, shorter periods receiving HAART, maternal concurring illnesses (anemia, IUGR, oligodydramnium), coinfections (CMV and toxoplasmosis) and the occurrence of labor. Use of HAART for longer periods, caesarian delivery and oral zidovudine for the newborns were associated with a decreased risk. Poor adhesion to treatment was present in 13 of the 15 cases of transmission; in 7, co-infections were diagnosed (CMV and toxoplasmosis). Conclusion: Use of HAART and caesarian delivery are protective factors in mother-to-child transmission of HIV. Maternal coinfecctions and maternal concurring illnesses were risk factors for MTCT.
Universidade Estadual de Campi
Ciencias Biomedicas
Mestre em Tocoginecologia

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Samleerat, Tanawan Barin Francis Leechanachai Pranee. "Transmission mère-enfant du virus de l'immunodéficience humaine de type 1 Rôle des anticorps neutralisants et caractéristiques moléculaires des variants transmis. /." S. l. : S. l. : S. n. ; S. n, 2008. http://theses.abes.fr/2008TOUR3302.

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Thèse de doctorat : Sciences de la vie et de la santé : Tours : 2008. Thèse de doctorat : Sciences de la vie et de la santé : CHIANG MAI UNIVERSITY : 2008.
Thèse soutenue en co-tutelle. Titre provenant de l'écran-titre.

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Marlin, Romain. "Rôle de l'immunité innée maternelle dans le contrôle de la transmission mère-enfant in utero du VIH-1." Paris 7, 2010. http://www.theses.fr/2010PA077128.

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Une meilleure compréhension de l'immunité innée et muqueuse est nécessaire pour la mise en place d'un futur vaccin protecteur contre le VIH-1. La muqueuse utérine pendant la grossesse (la décidua) apparaît comme un modèle pertinent de protection puisque la transmission mère-enfant du VIH-1 est rare in utero surtout pendant le premier trimestre de grossesse. Les objectifs de ce travail de thèse étaient de mettre en place un modèle d'étude de la décidua humaine afin d'étudier l'infection VIH-1 et d'identifier les mécanismes de contrôle pouvant être présent au sein de ce tissu. Au cours de cette thèse, nous avons mis en place et validé un modèle d'étude du tissu décidual humain à partir de produits d'IVG réalisées au premier trimestre. Nous avons montré que la décidua était permissive à l'infection in vitro par le VIH-1 et préférentiellement par les virus de tropisme R5. Les principales cibles du virus ont été caractérisées : il s'agit des cellules présentatrices d'antigène qui partagent des propriétés des macrophages M2 et des cellules dendritiques tolérogéniques. Le microenvironnement présent dans la décidua participe au contrôle de la dissémination virale notamment via la production de beta-chimiokines par les cellules immunes de la décidua. Nous avons également démontré une dynamique d'expression du phénotype des cellules NK de la décidua au cours du premier trimestre. Ces cellules pourraient être impliquées dans le contrôle de la dissémination du VIH-1 à l'interface materno-fœtale. La caractérisation des mécanismes de contrôle donnera des éléments d'informations pour l'élaboration de nouvelles stratégies vaccinales protectrices contre le VIH-1
A better understanding of the innate and mucosal immunity is needed for the design of a protective vaccine against HIV-1. The uterine mucosa during pregnancy (the decidua) is a relevant model of protection since in utero mother-to-child transmission of HIV-1 is rarely observed, particularly during the first trimester of pregnancy. The objectives of this PhD study were to develop a study model of human decidua to characterize HIV-1 infection, and to identify the potential mechanisms of viral control within this tissue. During this PhD, we have set up and validated an in vitro and ex vivo model to study the decidual mucosa obtained from voluntary pregnancy termination samples during the first trimester. We demonstrated that the decidua was permissive to in vitro HIV-1 infection and mostly by the R5 virus. The target cells were characterized: they are antigen presenting cells which share the phenotype of M2 macrophages as well as of tolerogenic dendritic cells. The microenvironement of the decidua participates in the control of viral dissémination especially through the production of beta- chemokines by decidual immune cells. We also showed that in vivo the decidual NK cell phenotype changes over time. These effector cells could potentially participate in the control of HIV-1 dissemination within the materno-fetal interface. The characterization of the control mechanisms will give new pieces of information relevant for the design of new strategies to develop a protective vaccine against HIV-1

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Kumar, Surender. "STUDIES TO UNDERSTAND THE MECHANISM OF HORIZONTAL AND VERTICAL TRANSMISSION OF HUMAN IMMUNODEFICIENCY VIRUS." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1290962181.

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Navarre, Vincent. "Transmission materno-foetale de l'infection au virus de l'immunodéficience humaine chez la femmes séropositives vivant à la Martinique : à propos de 67 grossesses." Lyon 1, 1992. http://www.theses.fr/1992LYO1M024.

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Protopapas, Stella A. B. A. "Mother to Child Transmission of Hepatitis C Virus in the Greater Cincinnati Area." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin154392119827537.

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Dunn, David Tyre. "Statistical methods for assessing the risk and timing of vertical transmission of Human Immunodeficiency Virus." Thesis, University College London (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266106.

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Fall, Abdoul Aziz. "Etudes de quelques modèles épidémiologiques : application à la transmission du virus de l'hépatite B en Afrique subsaharienne (cas du Sénégal)." Thesis, Metz, 2010. http://www.theses.fr/2010METZ003S/document.

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L'objectif de cette étude est la modélisation, la validation, l'analyse mathématique et la simulation de modèles de transmission de l'hépatite B en Afrique en général et au Sénégal en particulier. Nous proposons de nouveaux modèles bases sur les connaissances actuelles de l'histoire naturelle de la transmission du virus de l'hépatite B. Ainsi, nous présentons deux modèles de la transmission du VHB1, un modèle sans transmission verticale et un autre ou la transmission verticale de la maladie est prise en compte. Ce second modèle est justifié par la controverse, en ce qui concerne l'incidence des transmissions verticale ou périnatale au niveau de la zone Afrique ; entre d'une part, l'Organisation Mondiale de la Santé et d'autre part les spécialistes de l'hépatite B au Sénégal. Ces modèles, nous ont conduit à étudier des modèles épidémiologiques avec une diérentiabilitée, au niveau des susceptibles, et progression de stade pour les infectieux. Nous obtenons une analyse complète de la stabilité de ces modèles à l'aide des techniques de Lyapunov suivant la valeur du taux de reproduction de base R0. Ce qui nous conduit à l'étude d'un modèle épidémiologique beaucoup plus général qui englobe ceux proposés pour la modélisation de la transmission du virus de l'hépatite B. Nous illustrons à la fin de ce travail ces modèles par des simulations numériques. Ces dernières sont faites à partir de nos modèles confrontés aux données recueillies du programme de lutte contre l'épidémie de l'hépatite B au Sénégal et dans la littérature. Elles permettrons l'effet de la transmission verticale/périnatale du virus de l'hépatite B sur les politiques de Santé Publique
We propose new models based on the state of art and the epidemiology currently known from the transmission of the hepatitis B virus. Thus, we present two models of the transmission of Hepatitis Bvirus, a model without vertical transmission and another in which the vertical transmission of the disease is taken into account, This second model is justified by the controversy, with regard to the incidence of the vertical and perinatal transmission of the virus in some parts of Africa ; between the World Health Organization on one hand and hepatitis B's specialists in Senegal on the other hand. These models helped us to analyse epidemiological models with a differential susceptibility of the population, and stagged progression of infectious. We present a thorough analysis of the stability of the models using the Lyapunov techniques and obtain the basic reproduction ratio, R0 which allows into the study of general epidemiological models including those proposed for the transmission of the hepatitis B virus. Numerical simulations are done to illustrate the behaviour of the model, using data collected during the campaign against epidemic hepatitis B in Senegal and from published literature. These models enable the evaluation of the incidence of the vertical and perinatal transmission of the hepatitis B virus on the policies of Public Health

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Mognetti, Barbara. "Etude de la permissivité des cellules trophoblastiques humaines à l'infection par le VIH-1 in vitro." Paris 5, 1999. http://www.theses.fr/1999PA05S011.

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La transmission verticale du VIH peut avoir lieu par l'allaitement, à l'accouchement ou in utero. Nous nous sommes intéressés à la participation du trophoblaste à l'infection in utero. Nous avons étudié, in vitro, la permissivité des cellules trophoblastiques, issues de placentas à terme ou précoces, a l'infection par des isolats du VIH-1 (aux titres et phénotypes connus), obtenus de femmes enceintes et de leurs enfants. Nous avons aussi étudié l'expression, par les cellules trophoblastiques, des molécules impliquées dans l'entrée du VIH-1. Nous avons démontré que le trophoblaste à terme est extrêmement peu permissif a l'infection par des isolats naturels du VIH-1 in vitro : sept des huit préparations cellulaires étudiées étaient résistantes a l'infection. Malgré la présence, dans ces cellules, des ARNM pour CD4, CXCR4 et CCR5, aucune de ces molécules n'a été révélée à la membrane. Nous nous sommes aussi intéressés à l'infection des cellules trophoblastiques issues de placentas précoces (premier trimestre), obtenus par interruptions volontaires de grossesse induites par RU486. Sept des huit préparations de cellules trophoblastiques précoces que nous avons testées étaient permissives à l'infection. Les infections ont été inhibées par la présence d'AZT, mais non pas par la présence de SDF-1 (ligand de CXCR4), de MIP1, MIP1 et rantes (ligands de CCR5), ni d'un anticorps inhibiteur du cd4. Aucune réplication virale n'a été détectée. L'expression du CD4 à la membrane a été démontrée pour quatre des sept placentas testes. L'ARNM a été révélé dans trois placentas sur cinq. Tous les placentas précoces testes expriment CCR3, CCR5 et CXCR4, avec des niveaux d'expression différents. La présence d'ARNM pour d'autres corécepteurs a aussi été cherchée par RT-PCR. Chaque préparation cellulaire a montré une figure différente d'expression d'ARNM. Nous n'avons pas vu de corrélation entre l'expression de ces molécules et l’âge gestationnel des placentas.

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Patot, Sabine. "Virus manipulateurs du comportement des insectes : prévalence et influence sur la structure des communautés hôtes : Exemple de l'association Leptopilina boulardi / LbFV." Phd thesis, Université Claude Bernard - Lyon I, 2009. http://tel.archives-ouvertes.fr/tel-00451287.

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Les symbioses eucaryotes/micro-organismes constituent une importante source d'innovation évolutive et de diversité écologique. Ces associations sont très répandues chez les insectes, en particulier chez les insectes parasitoïdes (insectes parasites d'autres insectes) qui hébergent en particulier une grande diversité de virus transmis verticalement. Leurs effets directs sur les parasitoïdes ainsi que les effets indirects sur la structure des communautés sont à l'heure actuelle mal compris. Nous avons abordé ces questions au travers l'étude d'un virus héritable (LbFV) ayant la particularité de manipuler le comportement de superparasitisme de son hôte, l'hyménoptère parasitoïde de drosophiles Leptopilina boulardi. La mise au point d'un outil moléculaire diagnostic de l'infection nous a permis de montrer que ce virus, spécifique à L. boulardi, peut atteindre de fortes prévalences dans les populations d'hôtes. Nous avons également mis en évidence un effet de la présence du virus sur les interactions compétitives interspécifiques au sein de la communauté des parasitoïdes de drosophiles. L'approche intégrée de ce travail constitue une étape importante dans la connaissance du rôle des virus héritables sur l'écologie et l'évolution de leurs hôtes

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Longdon, Ben John. "Evolution and ecology of Drosophila sigma viruses." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5768.

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Insects are host to a diverse range of vertically transmitted micro-organisms, but while their bacterial symbionts are well-studied, little is known about their vertically transmitted viruses. The sigma virus (DMelSV) is currently the only natural hostspecific pathogen to be described in Drosophila melanogaster. In this thesis I have examined; the diversity and evolution of sigma viruses in Drosophila, their transmission and population dynamics, and their ability to host shift. I have described six new rhabdoviruses in five Drosophila species — D. affinis, D. obscura, D. tristis, D. immigrans and D. ananassae — and one in a member of the Muscidae, Muscina stabulans (Chapters two and four). These viruses have been tentatively named as DAffSV, DObsSV, DTriSV, DImmSV, DAnaSV and MStaSV respectively. I sequenced the complete genomes of DObsSV and DMelSV, the L gene from DAffSV and partial L gene sequences from the other viruses. Using this new sequence data I created a phylogeny of the rhabdoviruses (Chapter two). The sigma viruses form a distinct clade which is closely related to the Dimarhabdovirus supergroup, and the high levels of divergence between these viruses suggest that they may deserve to be recognised as a new genus. Furthermore, this analysis produced the most robustly supported phylogeny of the Rhabdoviridae to date, allowing me to reconstruct the major transitions that have occurred during the evolution of the family. This data suggests that the bias towards research into plants and vertebrates means that much of the diversity of rhabdoviruses has been missed, and rhabdoviruses may be common pathogens of insects. In Chapter three I examined whether the new sigma viruses in Drosophila affinis and Drosophila obscura are both vertically transmitted. As is the case for DMelSV, both males and females can transmit these viruses to their offspring. Males transmit lower viral titres through sperm than females transmit through eggs, and a lower proportion of their offspring become infected. I then examined natural populations of D. obscura in the UK; 39% of flies were infected and the viral population shows clear evidence of a recent expansion, with extremely low genetic diversity and a large excess of rare polymorphisms. Using sequence data I estimate that the virus has swept across the UK within the last ~11 years, during which time the viral population size doubled approximately every 9 months. Using simulations based on lab estimates of transmission rates, I show that the biparental mode of transmission allows the virus to invade and rapidly spread through populations, at rates consistent with those measured in the field. Therefore, as predicted by the simulations, the virus has undergone an extremely rapid and recent increase in population size. In Chapter four I investigated for the first time whether vertically transmitted viruses undergo host shifts or cospeciate with their hosts. Using a phylogenetic approach I show that sigma viruses have switched between hosts during their evolutionary history. These results suggest that sigma virus infections may be short-lived in a given host lineage, so that their long-term persistence relies on rare horizontal transmission events between hosts. In Chapter five I examined the ability of three Drosophila sigma viruses to persist and replicate in 51 hosts sampled across the Drosophilidae phylogeny. I used a phylogenetic mixed model to account for the non-independence of host taxa due to common ancestry, which additionally allows integration over the uncertainty in the host phylogeny. In two out of the three viruses there was a negative correlation between viral titre and genetic distance from the natural host. Additionally the host phylogeny explains an extremely high proportion of the variation (after considering genetic distance from the natural host) in the ability of these viruses to replicate in novel hosts (>0.8 for all viruses). There were strong phylogenetic correlations between all the viruses (>0.65 for all pairs), suggesting a given species’ level of resistance to one virus is strongly correlated with its resistance to other viruses. This suggests the host phylogeny, and genetic distance from the natural host, may be important in determining viruses ability to host switch. This work has aimed to address fundamental questions relating to host-parasite coevolution and pathogen emergence. The data presented suggests that sigma viruses are likely to be widespread vertically transmitted insect viruses, which have dynamic interactions with their hosts. These viruses appear to have switched between hosts during their evolutionary history and it is likely the host phylogeny is a determinant of such host shifts.

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Patot, Sabine. "Virus manipulateurs du comportement des insectes : prévalence et influence sur la structure des communautés hôtes : exemple de l’association Leptopilina boulardi / LbFV." Thesis, Lyon 1, 2009. http://www.theses.fr/2009LYO10103/document.

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Les symbioses eucaryotes/micro-organismes constituent une importante source d’innovation évolutive et de diversité écologique. Ces associations sont très répandues chez les insectes, en particulier chez les insectes parasitoïdes (insectes parasites d’autres insectes) qui hébergent en particulier une grande diversité de virus transmis verticalement. Leurs effets directs sur les parasitoïdes ainsi que les effets indirects sur la structure des communautés sont à l’heure actuelle mal compris. Nous avons abordé ces questions au travers l’étude d’un virus héritable (LbFV) ayant la particularité de manipuler le comportement de superparasitisme de son hôte, l’hyménoptère parasitoïde de drosophiles Leptopilina boulardi. La mise au point d’un outil moléculaire diagnostic de l’infection nous a permis de montrer que ce virus, spécifique à L. boulardi, peut atteindre de fortes prévalences dans les populations d’hôtes. Nous avons également mis en évidence un effet de la présence du virus sur les interactions compétitives interspécifiques au sein de la communauté des parasitoïdes de drosophiles. L’approche intégrée de ce travail constitue une étape importante dans la connaissance du rôle des virus héritables sur l’écologie et l’évolution de leurs hôtes
Eukaryots/microorganisms symbiosis is an important source of evolutionary novelty and ecological diversification. These associations are widespread in insects, particularly in parasitoids (insects that parasitize other insects) where a broad diversity of vertically transmitted viruses are found. However, their direct and indirect effects on host community are poorly understood. In this thesis, we used a system involving a Drosophila parasitoid, Leptopilina boulardi and a heritable virus LbFV that manipulates the behaviour of the parasitoid by increasing its tendency to lay eggs in a host that is already parasitized (superparasitism). Using a viral molecular marker developed in this work, we showed very high prevalences of the virus in L. boulardi populations. Additionally, we found a strong effect of the virus on interspecific competition in the Drosophila parasitoid community. The integrative approach of this work is an important step in understanding the role of heritable viruses in parasitoid ecology and evolution

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Grunnill, Martin David. "Inapparent and vertically transmitted infections in two host-virus systems." Thesis, University of Exeter, 2015. http://hdl.handle.net/10871/20866.

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Despite the advances made since the advent of germ theory, infectious diseases still wreak havoc on human societies, not only affecting us directly but impacting the crops and livestock upon which we rely. Infectious diseases also have dramatic effects on wildlife ecology. Therefore research into infectious diseases could not only directly lead to the improvement and saving of human lives, but aid in food security and the conservation of many wildlife species. Of vital importance in understanding the ecology of infectious diseases are the mechanisms by which they persist in host populations. One possible mechanism is vertical transmission: the transmission of a pathogen from a parent to its offspring as a result of the process of host reproduction. Another possible mechanism is inapparant infections, where an infected host does not display symptoms. Focusing on dengue fever and the Plodia interpunctella granulovirus laboratory system, this PhD thesis looks at the role these two mechanisms play on the persistence of two viral infections and their ecology. Regarding the Plodia interpunctella granulovirus (PiGV) low host food quality led to greater detection of vertically transmitted inapparant PiGV, but did not lead to its activation to an apparent form. Host inbreeding did not lead to vertically transmitted inapparant PiGV’s activation, nor had an effect on its vertical transmission. The vertical infection rate of PiGV was very low. I would therefore suggest that it may be better to use an insect virus system with a higher rate of vertical infection in future research into vertically transmitting inapparent infections. Regarding dengue virus I conclude that vertical transmission is not likely to play a role in the persistence of this virus. However modelling work found that inapparent infections could provide dengue viruses with a means of persistence and should be subject to further research.

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Samleerat, Tanawan. "Transmission mère-enfant du virus de l'immunodéficience humaine de type 1 : rôle des anticorps neutralisants et caractéristiques moléculaires des variants transmis." Thesis, Tours, 2008. http://www.theses.fr/2008TOUR3302/document.

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Ce travail a confirmé le rôle protecteur de certains anticorps neutralisants dans la TME du VIH-1, a permis de suggérer que certaines souches seraient de bons indicateurs d’anticorps neutralisants associés à la protection, et a confirmé le rôle de la région V2 de l’enveloppe virale en tant que cible des anticorps neutralisants. Les caractéristiques moléculaires des virus transmis dans le contexte de la TME confortent les données en faveur de la transmission à l’enfant d’une population virale restreinte génétiquement. Une gp 120 plus compacte et une moindre glycosylation ne sont pas des caractéristiques des virus transmis de la mère à l’enfant. Cependant, deux sites de N-glycosylation semblent être sélectionnés chez les virus transmis. L’identification de deux cas de TME liés à des variants issus de recombinaisons entre variants maternels a confirmé la présence d’un « hot spot » dans la région C2 du gène env, et a révélé pour la première fois un second « hot spot » dans la région C3
A lower risk of MTCT was associated with higher NAb titers against the CRF01_AE strain, MBA, in Thailand. The results suggest that some primary isolates may be useful indicators for identifying protective antibodies, and confirm the role of the V2 region in neutralization. We found that only viruses of a restricted subset were transmitted to the infant. We did not find that shorter gp120 or fewer PNGS were characteristics of viruses transmitted from mother to infant. However, a limited number of PNGS, particularly at positions N301 and N384, may confer an advantage on the virus to be transmitted. Moreover, we identified two cases that suggest that recombination probably contributed to adaptation of HIV-1 to its environment to be successfully transmitted from mothers to their infants. In addition, our data allow both to confirm, in natural in vivo conditions, a hot spot for recombination in the C2 region of HIV-1 envelope gene, and to suggest another hot spot in the C3 region

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22

Guo, Hailong. "Antigenic epitope composition and protectivity of avian hepatitis E virus (avian HEV) ORF2 protein and vertical transmission of avian HEV." [Ames, Iowa : Iowa State University], 2006.

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A, Fall A. "Etude de quelques mod èles épid emiologiques : application à la transmission du virus de l'h épatite B en Afrique subsaharienne (S én égal)." Phd thesis, Université de Metz, 2010. http://tel.archives-ouvertes.fr/tel-00857686.

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L'objectif de cette etude est la mod elisation, la validation, l'analyse math ematique et la simulation de mod eles de transmission de l'h epatite B en Afrique en g en eral et au S en egal en particulier. Nous proposons de nouveaux mod eles bas es sur les connaissances actuelles de l'histoire naturelle de la transmission du virus de l'h epatite B. Ainsi, nous pr esentons deux mod eles de la transmission du VHB1, un mod ele sans transmission verticale et un autre o u la transmission verticale de la maladie est prise en compte. Ce second mod ele est justi e par la controverse, en ce qui concerne l'incidence des transmissions verticale ou p erinatale au niveau de la zone Afrique ; entre d'une part, l'Organisation Mondiale de la Sant e et d'autre part les sp ecialistes de l'h epatite B au S en egal. Ces mod eles, nous ont conduit a etudier des mod eles epid emiologiques avec une di erentiabilit e, au niveau des susceptibles, et progression de stade pour les infectieux. Nous obtenons une analyse compl ete de la stabilit e de ces mod eles a l'aide des techniques de Lyapunov suivant la valeur du taux de reproduction de base R0. Ce qui nous conduit a l' etude d'un mod ele epid emiologique beaucoup plus g en eral qui englobe ceux propos es pour la mod elisation de la transmission du virus de l'h epatite B. Nous illustrons a la n de ce travail ces mod eles par des simulations num eriques. Ces derni eres sont faites a partir de nos mod eles confront es aux donn ees recueillies du programme de lutte contre l' epid emie de l'h epatite B au S en egal et dans la litt erature. Elles permettrons l' evaluation de l'incidence de la transmission verticale/p erinatale du virus de l'h epatite B sur les politiques de Sant e Publique.

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Viñolas, Tolosa Maria. "Transmissió vertical del virus de l’hepatitis C. Factors de risc, història natural dels nens infectats i evolució a llarg termini." Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/384220.

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Introducció: La TV del VHC succeeix en el 5-15% dels casos i depèn de factors de risc materns, obstètrics i neonatals. Fins el moment existeix poca informació sobre l’evolució dels nens infectats més enllà dels 2 o 3 primers anys de vida. L’objectiu del present estudi es determinar la taxa de TV, els factors de risc i l’evolució a llarg termini dels nens infectats. Pacients i mètodes: Estudi prospectiu de cohorts de 120 gestants infectades per VHC i els seus fills nascuts a l’Hospital del Mar de Barcelona entre gener de 1994 i desembre de 1996, amb seguiment de 36 mesos per a tots els nens, i de 17-20 anys pels nens infectats. Es registren dades maternes i obstètriques i es realitza ARN-VHC qualitativa i quantitativa a les gestants al part. Es registren les dades neonatals i es fa seguiment dels nens cada 3 mesos fins l’any i mig i cada 6 mesos fins els 3 anys, recollint dades somatomètriques i realitzant proves hepàtiques, anticossos del VHC i ARN-VHC. Els nens infectats són visitats cada 6 mesos, realitzant proves hepàtiques i ARN-VHC i, en cas d’hepatitis crònica, biòpsia hepàtica. Resultats: L’edat mitjana de les mares fou de 28,2 ± 5,0 anys. La via de contagi del VHC fou majoritàriament per addicció a drogues via parenteral (ADVP), present en 79 mares (65,8%); 22 mares (18,3%) estaven diagnosticades d’hepatitis crònica activa; 50 (41,7%) estaven coinfectades per VIH i 34 (28,8%) van consumir heroïna durant la gestació. Es van infectar per VHC 14 dels nounats, donant una taxa de TV del VHC del 11,7% (IC 95%: 6,0-17,5). Aquesta taxa augmenta al 14% (IC 95%: 6,7-21,3) en mares amb ARN-VHC positiu, al 16,0% (IC 95%: 11,9-20,2) en mares coinfectades per VIH, al 29,2% (IC 95%: 11,0-47,4) en mares amb hepatitis crònica i al 21,8% (IC 95%: 11,0-32,7) en mares amb sociopatia. Els factors de risc de la transmissió vertical estadísticament significatius foren la càrrega viral materna al part, amb taxa de TV del VHC en mares amb càrrega viral >3,9 x105 còpies/ml del 40% (IC 95%: 18,5-61,5), la presència d’hepatitis crònica materna, l’edat materna inferior a 25,0 ± 4,7 anys, la sociopatia materna i la presència de síndrome d’abstinència neonatal. No han estat factors de risc la coinfecció materna per VIH i VHC, l’ADVP, el tipus de part o el sexe del nadó. Cap dels 13 nens nascuts per cesària electiva han estat infectats per TV. El seguiment dels nens infectats mostra bona evolució clínica, sense hepatitis aguda però amb hepatitis crònica de lleu activitat a la biòpsia hepàtica. La taxa de guarició espontània és del 72,7%, essent els factors que hi influeixen la menor càrrega viral materna del VHC al part i el serotipus diferent de l’1. Els nens que guarien espontàniament presentaven menys determinacions positives d’ARN-VHC i menor càrrega viral durant el primer any de vida. Els nens infectats per VHC seguits fins l’edat adulta han precisat seguiment per psiquiatria en els 63% el casos i el 73% presenten conductes de risc social. Cap d’ells presenta addicció a drogues via parenteral. Conclusions: La taxa de TV del VHC és del 11,7% i està influïda principalment per la càrrega viral materna, influint també l’ hepatitis crònica en la gestant, la menor edat de la mare i la sociopatia. La cesària electiva podria ser factor protector de la TV del VHC. El 72,7% dels nens infectats guareixen espontàniament la infecció, sobretot durant els tres primers anys de vida. La sociopatia dels seus pares influeix en l’evolució física, social i psiquiàtrica dels nens infectats.
Introduction: The VT-HCV occurs in 5-15% of cases and depends on maternal risk factors, obstetric and neonatal. So far there is little information on the evolution of infected children beyond the first two or three years. The aim of this study was to determine the rate of VT-HCV, risk factors and long-term evolution of infected children. Patients and Methods: Prospective cohort study of 120 HCV-infected pregnant women and their children born at the Hospital del Mar in Barcelona between January 1994 and December 1996, with follow-up of 36 months for all children and 17-20 years for infected children. Maternal and obstetric data recorded and performed HCV RNA qualitative and quantitative pregnant women for childbirth. Data recorded track of neonatal and children every three months to a year and a half every 6 months to 3 years, collecting growth data and testing liver, HCV antibody and HCV-RNA. The infected children are visited every six months, performing liver tests and HCV-RNA, and in case of chronic hepatitis, liver biopsy. Results: The average age of mothers was 28.2 ± 5.0 years. The route of transmission of HCV was mainly intravenous drug addiction (ADVP), present in 79 mothers (65.8%); 22 mothers (18.3%) were diagnosed with chronic active hepatitis; 50 (41.7%) were coinfected with HIV and 34 (28.8%) consumed heroin during pregnancy. HCV infection were in 14 newborns, giving a flat rate of HCV 11.7% (95% CI 6.0 to 17.5). This rate increases to 14% (95% CI 6.7 to 21.3) in HCV-RNA positive mothers, at 16.0% (95% CI 11.9 to 20.2) in HIV co-infected mothers, at 29.2% (95% CI 11.0 to 47.4) in mothers with chronic hepatitis and 21.8% (95% CI 11.0 to 32.7) in mothers with sociopath. Risk factors for vertical transmission were statistically significant maternal viral load to part with a flat rate of mothers with HCV viral load> 3.9 x105 copies / mL of 40% (95% CI: 18.5 to 61 5), the presence of chronic hepatitis maternal, maternal age lower than 25.0 ± 4.7 years, maternal sociopath and the presence of neonatal drug abstinence syndrome. There are risk factors for HIV and HCV coinfection mother, the ADVP, the type of part or the sex of the baby. None of the 13 children born by elective caesarean section have been infected by VT. Monitoring of infected children show good clinical evolution, without acute hepatitis but mild activity chronic hepatitis on liver biopsy. The spontaneous clearence rate is 72.7% and the factors that influence is lower maternal HCV viral load at delivery and serotypes non-1. Children with spontaneous clearance showed less determinations positive HCV-RNA and lowed viral load during the first year of life. HCV infected children followed until adulthood have needed psychiatric monitoring in the 63% cases and 73% have social risk behaviors. None of them appears intravenous drug addiction. Conclusions: The rate of HCV TV is 11.7% and is influenced mainly by maternal viral load, also influencing the chronic hepatitis in pregnant women, the younger of the mother and sociopath. The elective cesarean might be protective factor. 72.7% of children infected have spontaneous clearence, especially during the first three years of life. The sociopath of their parents influence the physical, social and psychiatric evolution of infected children.

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Millet, Geneviève. "Suivi sur cinq ans de 50 enfants nés de mères séropositives a la maternité de la belle de mai." Aix-Marseille 2, 1992. http://www.theses.fr/1992AIX20014.

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Du, Preez Antoinette. "Intrapartumpraktykgebruike om vertikale oordrag van MIV te beperk / Antoinette du Preez." Thesis, North-West University, 2004. http://hdl.handle.net/10394/407.

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An emergency reaction is required in Africa because HIVIAIDS is a reality which may be regarded as a developing crisis and a catastrophe. Approximately a third of all women in the North-West Province are HIV positive. Because of their vulnerability against HIVIAIDS there arose a need for health service provision to the HIV positive woman to focus specifically on the reduction of the transmission of HIVIAIDS from mother to child. Mother to child transmission is the biggest cause of HIV infection among children. Almost all HIV positive children are infected during pregnancy, labour, childbirth or breastfeeding. Without the necessary preventative measures as many as 25-35% of the children of HIV positive mothers may be infected. The biggest percentage of infections, however, takes place during labour and the birth process. In first world countries the mother has access to choices and facilities to make an informed decision about antiretroviral therapy, as well as the method of birth. In the North-West Province not all these options and facilities are available, and therefore the knowledge and skills of midwives must be deployed to reduce vertical transmission of HIV during the intrapartum practice. It is important that midwives have the necessary knowledge about intrapartum practices and vertical transmission of HIV, in order to distinguish between risky and safe intrapartum practices. The purpose of this research was to determine whether midwives in the Southern region of the North-West Province have sufficient knowledge of intrapartum practices to reduce vertical transmission of HIV, as well as to determine the intrapartum practices in the Southern region of the North-West Province. The ultimate goals, then, were to determine how the national policy should be adapted and implemented in the Southern region of the North-West Province to reduce HIV transmission during intrapartum practices. A quantitive survey design was used. For the data collection a questionnaire and a control list were used. The questionnaire and the control list, which are adapted and based on literature, were submitted to research and subject specialists, after which they were adapted. Permission was obtained for this research from the Department of Health in the North-West Province, the ethics committee of the PU for CHE as well as each provincial hospital in the Southern region in the North-West Province to conduct the research. A purposeful availability sample of midwives working in the Southern region of the North-West Province was used and a random sample was used for auditing the obstetric records. A total of 31 midwives participated as respondents, and 401 obstetrical records were audited. Data analysis was performed by means of a frequency analysis, effect sizes and cross reference. Based on these findings it was concluded that the midwives do have basic knowledge regarding vertical transmission of HIV, but that this knowledge is not reflected in the intrapartum practice. There is uncertainty about certain aspects where the latest research about intrapartum practices are not implemented in practice. Recommendations were accordingly formulated for nursing education, research and practice. This research particularly focused on improving midwives' knowledge about intrapartum practices to reduce the vertical transmission of HIV, so that this knowledge may result in improved intrapartum practice. Recommendations are also made as to how the national policy may be adapted and implemented in the Southern region of the North-West Province.
Thesis (M.Cur.)--North-West University, Potchefstroom Campus, 2004.

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Feracin, Jussara Cunha Fleury. "Situações que limitam a prevenção da transmissão vertical do HIV/AIDS em região do interior de São Paulo : estudo com abordagem quantitativa e qualitativa." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/313843.

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Orientadores: Ana Maria Segall Correa, Antonieta Keiko Kakuda Shimo
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas
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Resumo: Constitui prioridade de pesquisa e intervenção no Brasil a transmissão vertical do vírus HIV, infecção que tem aumentado entre as mulheres em idade fértil, resultando em progressiva redução na relação homem/mulher. O objetivo deste trabalho é analisar as ações de prevenção da transmissão vertical do vírus da AIDS durante o pré-natal, parto e puerpério, bem como as ações de vigilância epidemiológica, entre as mulheres grávidas soropositivas ao vírus HIV, residentes em um município do interior do estado de São Paulo. Trata-se de estudo realizado em duas fases, com abordagem quantitativa na primeira e qualitativa na segunda. Na primeira, descreve-se a situação epidemiológica dos 11 municípios pertencentes àquele Departamento, no período de janeiro de 2000 a dezembro de 2005, partindo-se das notificações e das fichas epidemiológicas de 112 gestantes portadoras do vírus HIV e das crianças nascidas destas gestações. As informações referem-se à idade das mulheres, local de sua moradia, momento de identificação da infecção, local e data do parto, além daquelas relativas aos procedimentos assistenciais terapêuticos e profiláticos. Na abordagem qualitativa, ou seja, na segunda fase foram realizadas entrevistas nas quais foi utilizado um roteiro padronizado e pré-testado com enfermeiros e médicos que prestam atendimento às gestantes e parturientes nas Unidades Básicas de Saúde e Hospital do município sede do Departamento Regional. Os resultados mostram, entre outras coisas, que todas as gestantes residiam em zona urbana, a maioria era branca (67,9%), de baixa escolaridade, sendo que mais de dois terços não haviam completado o primeiro grau e 42,9% tinham idade abaixo de 25 anos. Mais da metade conhecia seu status de soro-positividade antes da gravidez (53,6%) e para 10,7%, essa era a 2ª gravidez após o diagnóstico. Foram observadas falhas na profilaxia da transmissão vertical na gestação, parto e pós-parto. Nessa última intervenção, 17 mulheres não receberam AZT intravenoso e três recém-nascidos não fizeram profilaxia com AZT oral e outros três iniciaram a profilaxia 24 horas depois do parto. A estimativa de transmissão vertical do HIV foi de 4,5%. Na etapa qualitativa, foi observado que as solicitações de exames anti-HIV eram rotina estabelecida no pré-natal, não havendo, no entanto, aconselhamento pré e pósteste. No momento que antecede o parto, é sempre solicitado teste rápido. A necessidade da profilaxia, a indicação do parto cesariano e a inibição da lactação são de conhecimento dos profissionais, porém, esses profissionais não referem à forma como manejam essas intervenções. Conforme dados epidemiológicos resultantes desta pesquisa, algumas atitudes relacionadas à assistência às gestantes HIV positivas e a seus filhos não atendem as recomendações do Ministério da Saúde para a redução da transmissão vertical e as falas dos profissionais reforçam a necessidade de programas de capacitação e treinamentos na forma de educação continuada sobre o assunto para alcançar o objetivo proposto nas diretrizes nacionais de saúde
Abstract: A priority for public health research and intervention in Brazil is the vertical transmission of the AIDS virus, which has increased among women of reproductive age, resulting in a decreasing male/female ratio. The objective of this study is to analyze actions to prevent the vertical transmission of the AIDS virus during pregnancy, childbirth, and postpartum period, as well as the actions of epidemiological monitoring, of HIV-positive pregnant women residing in a city in the interior of the state of São Paulo. The study has two phases, one quantitative and the other qualitative. The first phase consisted of a descriptive study of the epidemiological situation in 11 municipalities pertaining to the Department of Health in the period from January, 2000, to December, 2005, based on epidemiological notifications and case records of HIV-positive pregnant women and the children resulting from those pregnancies. Information collected included the women's age, residence; time the HIV infection was identified, locale and date of delivery, as well as data on therapeutic and prophylactic care procedures. In the qualitative phase of the study, semi-structured interviews were conducted with nurses and physicians working in Primary Health Care Units and hospitals in the city where the Regional Health Department is located and, who provide care to the pregnant women and newborns. All the pregnant women reside in the urban area, most are White, with low educational levels, and 42.9% were less than 25 years old. More than half were aware of their HIV-positive status before becoming pregnant, and 10.7% of these were in their second pregnancy after having been diagnosed. Errors were observed in prophylactic procedures to prevent vertical transmission during pregnancy, during childbirth, and post-partum. With reference to the latter, 17 women were not given intravenous AZT, three newborns were not given AZT orally, and an additional three initiated prophylaxis 24 hours postpartum. The estimated vertical transmission of HIV was 4.46%. In the qualitative phase, it was observed that requests for anti-HIV tests were routine in pre-natal care, but with no counseling provided before or after the test. A rapid test is routinely requested at the moment just before childbirth, but there are no institutional standardized procedures that obligate staff to follow the recommendations that come with the test. The need for prophylaxis, cesarean birth, and inhibition of lactation are known by the professionals, however they do not refer to the way they normally deal with those procedures with the women. It was also observed that pediatricians deal better than other professionals with patients diagnosed as HIV-positive. The observed failures in health care and epidemiological surveillance for HIV-positive pregnant women and for their children confirm that the Ministry of Health HIV/AIDS protocols were not always followed by the health professionals, which shows the needs for continuing education, as they themselves pointed out
Doutorado
Saude Coletiva
Doutor em Saude Coletiva

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28

Pikora, Cheryl A. "Type-Specific Immunity in HIV-1 Vertically Infected Infants." eScholarship@UMMS, 1995. https://escholarship.umassmed.edu/gsbs_diss/83.

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High frequencies of CTL recognizing laboratory strains of HIV-1 are present in HIV-1 infected adults as early as preseroconversion. The presence of HIV-1 specific CTL during primary infection has been correlated with better control of early viremia and a more delayed onset of CD4 lymphocyte loss. Previous experiments in our laboratory have demonstrated that, unlike HIV-1 infected adults, the majority of vertically infected infants lack CTL which recognize laboratory strains of HIV-1 within the first year of life. ADCC antibody responses against laboratory strains of HIV-1 env gene products are also delayed until at least two years of age. As a possible correlate, disease progression is also more rapid in vertically infected infants. We hypothesized that HIV-1-specific CTL are type-specific in early infancy and that the use of target cells expressing laboratory strain gene products might limit the detection of HIV-1-specific CTL. To address this hypothesis, HIV-1 env genes from early isolates of four infants were PCR amplified, cloned, and used to generate recombinant vaccinia vectors (vv). The frequencies of CTL precursors (CTLp) recognizing env gene products from autologous isolates and the IIIB strain of HIV-1 were measured at time points from early infancy to 19 months using limiting dilution analysis (LDA). ADCC titers were also measured against autologous and IIIB env gene products at 4 time points spanning 2 months to 2 years of age. CTL precursors from 3 of 4 of these patients were specific only for autologous HIV-1 env gene products during the first 6 to 12 months of age. A pattern of CTL responsiveness was observed in these 3 patients in which type-specific CTL precursors observed in early infancy were replaced by cross-reactive, group-specific CTL by 6 to 12 months of age. CTL precursors from a fourth patient at 12 months of age recognized IIIB env and 1 out of 2 envs derived from 2 autologous viral isolates. High titers titers of ADCC antibodies against autologous env were detected in two infants prior to the detection of ADCC antibodies to IIIB. In two other infants, group specific ADCC antibody responses were detected in late infancy. Our results demonstrate that young infants can mount HIV-1 specific CTL and ADCC responses. The ability of young infants to mount cellular immune responses to HIV-1 also provides support for the concept of perinatal vaccination to prevent HIV-1 transmission. Furthermore. the lack of broadly-reactive CTL in early infancy suggests that the use of vaccines based on laboratory strains of HIV-1 may not afford protection from vertical infection.

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Lima, Maria Patelli Juliani Souza. "Infecção pelo virus da hepatite C entre parturientes : soroprevalencia, analise dos fatores de risco, infectividade e transmissão vertical." [s.n.], 1999. http://repositorio.unicamp.br/jspui/handle/REPOSIP/311835.

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Orientador: Rogerio de Jesus Pedro
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas
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Resumo: O estudo realizado no Hospital Universitário da Pontifícia Universidade Católica (PUC) de Campinas entre janeiro de 1994 e julho de 1998 constou de duas partes: a primeira, sobre a soroprevalência do VHC entre parturientes, os fatores de risco envolvidos e o potencial de infectividade entre as mulheres com anti-VHC-EIA positivo, e a segunda, sobre a transmissão vertical do VHC. Na investigação da prevalência dessa infecção, participaram 6.995 mulheres que tiveram o sangue coletado na sala de parto e que responderam a uma entrevista padrão, realizada durante a internação, objetivando a pesquisa de antecedentes epidemiológicos relativos a microorganismos veiculados pelas vias sangüínea e (ou) sexual. Utilizaram-se análises de associação e modelos de regressão múltipla na relação da positividade do RIBA e da presença do RNA-VHC com as variáveis epidemiológicas. A prevalência anti-VHC pelo EIA-3 foi de 1,5% (104/6.995) e de 0,8% após o RIBA-3. Nessa população, obteve-se também a positividade do anti-HIV-EIA de 1,0% e de 0,9% segundo o "Western blot"; a positividade do HBsAg de 0,5% e do anti-HBc de 6,8%; 0,9% de positividade anú-T.pallidum (VDRL e FTA-ABS). Com o teste RT-PCR, pesquisou-se o RNA-VHC em 75 mulheres reativas ao anti- VHC-EIA, e 35 (46,7%) amostras foram positivas. Das 47 amostras com RIBA reagente, 20 (42,6%) apresentaram níveis alterados de ALT, com RNA-VHC em 90% delas, e nas 12 amostras indeterminadas, 2 (16,7%) tinham níveis alterados de ALT, com RNA presente em 50%. No modelo de regressão logística múltipla, as cinco variáveis preditoras da positividade do RIBA, marcador de infecção prévia pelo VHC, foram: uso de bebida alcoólica, transfusão de sangue, pertencer a raça negra, antecedente de DST e anti-HBc positivo. Não foi possível compor esse modelo com a variável uso de drogas injetáveis e VDRL positivo. Repetiu-se a análise multivariada, após controlar as variáveis relativas à transmissão parenteral do VHC, para explorar o potencial da via sexual na transmissão do VHC. Antecedente de DST, presença do anti-HBc, ter ou ter tido parceiro sexual com história de hepatite ou parceiro heterossexual promíscuo foram determinantes da positividade do RIBA. Procurou-se associar os resultados do teste RT-PCR às características do RIBA, aos níveis de ALT, à co-infecção pelo HIV ou VHB e às variáveis epidemiológicas estudadas. Na análise multivariada, as variáveis que estimaram a presença do RNA-VHC foram as interações das bandas cl00-3 - c33c e c22-3 - c33c. Na segunda parte deste estudo, referente à transmissão vertical do VHC, participaram 61 mulheres com anti-VHC-EIA positivo e os respectivos filhos, de 72 partos acompanhados seqüencialmente. Entre o 2° e o 18° mês de vida, coletou-se, no mínimo, uma amostra de sangue. Dessas 72 crianças, 45 tinham mães com RIBA positivo, 13 indeterminado e 14 negativo, sendo 42 delas filhas de mulheres com viremia (39 com RIBA positivo e 03 indeterminado). Dentre os 42 lactentes, incluindo 09 filhos de mães co-infectadas pelo HIV, um apresentou repetidamente o RNA-VHC aos quatro meses de idade, evoluindo com alterações nos níveis de ALT entre o 7º e 11° mês de vida. A positividade da sorologia anti-VHC (EIA e RIBA) desta criança manteve-se até o 18° mês de vida, atendendo ao critério diagnóstico proposto para infecção vertical pelo VHC. A taxa de transmissão foi de 2,4% (01 em 42) e de 3% ao se excluírem as crianças de mulheres co-infectadas pelo HIV (01 em 33). Este estudo demonstrou que a prevalência anti-VHC-EIA entre as mulheres grávidas é superior à dos doadores de sangue do mesmo hospital; que a exposição sexual pode ser um importante fator na disseminação do VHC; e que a transmissão vertical do VHC ocorre, porém, com freqüência baixa
Abstract: This study performed at the University Hospital of the Pontifícia Universidade Católica de Campinas (PUC-Campinas) between January of 1994 and July of 1998 was divided into two parts: the first was about the HCV prevalence among parturients, the risk factors involved in it and the infectivity potential among anti HCV-EIA positive women; the second one was about vertical transmission of the HCV. A total of 6995 women have participated in the HCV prevalence study. The women answered a standard questionnaire during their stay in the hospital and had their blood collected in the obstetric center. These two procedures were performed in order to study the epidemiological history related to pathogens of sexual or blood-borne transmission. Analyses of association and models of multiple regression were utilized in association of the RIBA and HCV RNA positivity with the epidemiological variables. The anti-HCV seroprevalence by EIA-3 was 1.5% (104/6995) and after RIBA-3 was 0.8%. It was obtained in this population anti-HIV-EIA seropositivity of 1.0% and 0.9% according to the Western blot; HBsAg positivity of 0.5% and anti-HBc of 6.8%; and 0.9% of the anti T.pallidum positivity (VDRL and FTA-abs). The HCV RNA was studied, utilizing RT-PCR, in 75 anti-HCV-EIA reactive women, resulting in 35 (46,7%) positive samples. Of the 47 RIBA-reactive samples, 20 (42,6%) showed abnormal alanine aminotransferase (ALT) levels with HCV RNA in 90% of them and, of the 12 eterminate samples, 2 (16,7%) had abnormal ALT levels with HCV RNA in 50% of them. In the model of multiple logistic regression, five independent predictors of RIBA positivity, the marker of previous HCV infection, were: alcohol use, blood transfusion, race (blacks), a history of STD and anti-HBc positivity. It was not possible to build this model with the variables - injectable drug use and positive VDRL . The model of multiple logistic regression was repeated, after controlling for parenteral exposure, in order to explore the potential of the sexual via in HCV transmission. A history of STD, anti-HBc positivity and having or having had promiscuous heterosexual partner or sex partner with a history of hepatitis were determinants of RIBA positivity. The results of RT-PCR test were tested in the association with the characteristics of RIBA results, with ALT levels, with HIV or VHB coinfection, and with the epidemiological variables studied. In the multivariate analysis, RNA HCV was estimated by interactions of the C100 - C33c and of the C22-3 - C33c bands. A total of 61 anti-HCV-EIA-positive women and their respective children, of 72 sequentially assisted deliveries, participated in the second part of this study, which was about HCV vertical transmission. Between the 2nd and the 18th month of age, at least oneblood sample was collected from mother-child. Forty-five out of these children had RIBA-positive mothers; 13 had indeterminate RIBA; and 14 had negative RIBA. Forty-two of them were children of women with viremia: 39 had RIBA-positive mothers and 3 indeterminate. Among the 42 infants there were 09 whose mothers were HIV coinfected. From this total of 42, one presented the RNA-HCV repeatedly at the fourth month of age and he also showed abnormal ALT levels between 7° and 11° month of age. Anti-HCV (EIA and RIB A) positivity of this child was kept until the 18th month of live, according to the proposed diagnostic criteria of vertical transmission. The transmission rate was 2.4% (1 in 42) and 3%, being excluded the children of the HIV-coinfected women (1 in 33). This study has demonstrated that anti-HCV-EIA prevalence was higher in pregnant women than in blood donors of the same hospital; that sexual exposure may be an important factor to the spreading of HCV; and that vertical HCV transmission occurs, but with a low frequency
Doutorado
Clinica Medica
Mestre em Ciências Médicas

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30

McNeilly, Tom N. "Respiratory transmission of maedi-visna virus." Thesis, University of Edinburgh, 2005. http://hdl.handle.net/1842/30497.

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Using an ovine tracheal organ culture model it was found that tracheal mucosa was infectable with MVV, but this infection was inefficient and non-productive, with doses of ≥ 1 x 10⁵TCID₅₀ required for detectable infection. Virus containing cells were located in a sub-epithelial location within 12 hours post-infection, but never in the tracheal epithelium. In addition, mechanical disruption of the epithelium resulted in a significant increase in virus uptake. These results suggest that tracheal epithelium acts as a barrier to MVV uptake, and is not a primary target for MVV. Immunohistochemical (IHC) analysis of tracheal mucosa identified an extensive network of sub-epithelial dendritic cells in the same location as provirus positive cells, suggesting uptake of MVV by the trachea is mediated by dendritic cells. In vivo tracking of intra-tracheal inocula using patent blue dye demonstrated exposure of both trachea and lower lung. Differential exposure of trachea and lower lung to MVV demonstrated lower lung to be significantly more efficient at MVV uptake. It was shown that virus instilled into the lower lung is taken up by alveolar macrophages (AMs), and that MVV-infected AMs are capable of transferring virus into the body. In vivo tracking of MVV infected AMs with PKH-26 dye failed to demonstrate migration of AMs from the lung airspace, suggesting that during infection, virus is transferred from AMs into the body via an indirect route. It was hypothesised that lower lung inflammation may play a key role in initial MVV entry into the body via recruitment of viral target cells, namely macrophages and dendritic cells, and that infected AMs may play a central role in this inflammation. Histopathological, IHC and real-time PCR analysis of virus treated lung tissue failed to detect an early inflammatory response.

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Centeville, Maraisa 1971. "Sobrevivencia de crianças infectadas por transmissão vertical pelo virus da imunodeficiencia humana do tipo 1(HIV-1)." [s.n.], 2003. http://repositorio.unicamp.br/jspui/handle/REPOSIP/313421.

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Orientadores: Maria Marluce dos Santos Vilela, Ricardo Cordeiro
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
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Resumo: A partir da revisão dos prontuários de 165 crianças com infecção congênita pelo HIV-1 seguidas no Ambulatório de Imunodeficiência Pediátrica do Hospital de Clínicas da UNICAMP, construímos curvas de sobrevida abrangendo o período de 1989 a 1999. Os sujeitos foram divididos em três grupos segundo seu ano de início de seguimento ambulatorial. O primeiro grupo incluiu crianças que iniciaram seu seguimento entre 1989 e 1992, quando o único tratamento disponível era a zidovudina (AZT), indicada apenas em estágios avançados da doença. O segundo grupo foi de 1993 a 1996, quando já existiam outros medicamentos disponíveis, sua indicação era mais precoce e o avanço do conhecimento da doença permitiu medidas preventivas da transmissão vertical. O terceiro grupo abrangeu o período de 1997 a 1999, quando foram introduzidos os inibidores de protease, classe de medicamentos mais eficazes em interromper a replicação viral. As curvas de sobrevida construídas a partir desses grupos mostraram-se significativamente diferentes, ocorrendo maior risco de óbito conforme a gravidade da doença e a precocidade do início do seguimento e diagnóstico, não havendo mudança no risco de óbito relacionado a outras variáveis, como gênero, peso de nascimento e aleitamento materno
Abstract: By the record review of 165 HIV-1 perinatally infected children followed at HC-UNICAMP Immunologic Pediatrics Service, between 1989 and 1999, data were gotten for this population construction of a survival curves. The population was divided into three groups according to its follow-up starting: Group 1: from 1989 t0 1992; Group 2: from 1993 to 1996; Group 3: from 1997 to 1999. These periods were based on treatment changes and on improuving knowledges about disease. In the first period the current treatment was the use of AZT, and it was just started whem the child was severily simpthomatic. In the second period there were more avaiable drugs, and the first treatment must be the combination of two drugs. A new kind of drugs was aviable in the third period. They would be protease inhibitor, used together with the previous ones. This association can inhibit the viral replication completely. Our data showed that the three groups survival expectance was diferent. The survival expectance is bigger in group 3 than in group 2 and group 1. It probably reflects the drug treatment improvement, as well as the support offered to these patients. We also found that early onset simptoms and clinical classification C at folow-up starting were associated with lower survival expectance. In other hand, birth weight, gender and breast feeding were not correlated with survival expectance changes
Mestrado
Pediatria
Mestre em Saude da Criança e do Adolescente

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32

Boilard, Aurélie. "Ontogenèse du microbiote chez le poisson vivipare Brachyistius frenatus : transmission verticale de symbiotes microbiens pionniers?" Master's thesis, Université Laval, 2021. http://hdl.handle.net/20.500.11794/69498.

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Chez les Mammifères, le recrutement du microbiote débute in utero, ce qui restait à démontrer chez d'autres classes de Vertébrés. L’objectif général du projet était de tester si un tel recrutement se produit chez un Vertébré non Mammifère. Nous avons testé, chez le Poisson vivipare Brachyistius frenatus, l'hypothèse selon laquelle la poche utérine est colonisée par un microbiote transmissible aux alevins, conférant à leur propre microbiote une ontogenèse semblable à celle des Mammifères. Le projet visait l’atteinte des objectifs suivant: i) caractériser le mode de transmission du microbiote, ii) établir la composition, la diversité et les relations des communautés bactériennes du microbiote des femelles, des juvéniles et de leur environnement et iii) déterminer l’ontogenèse du microbiote chez B. frenatus. Ce projet a permis de caractériser le mode de transmission du microbiote, sa séquence de recrutement, ainsi que la contribution respective de différentes communautés sources en caractérisant la diversité bactérienne du microbiote des femelles, des juvéniles et de leur environnement avec une approche métagénomique de type code barre. La région V4 du gène de l'ARNr 16S a été ciblée comme marqueur taxonomique bactérien pour identifier les taxons des différents échantillons.Cette étude nous a permis d’identifier le premier cas d’une transmission verticale du microbiote in utero chez un vivipare non Mammifère et les résultats sous-entendent que B. frenatus est peut-être un tout nouveau modèle d’ontogenèse du microbiote. Cette étude a permis l’acquisition des connaissances sur la transmission du microbiote et, dans le contexte de convergence évolutive de la viviparité, elle ouvre à de nouvelles perspectives quant aux avantages évolutifs d'une telle transmission de symbiotes microbiens.
In Mammals microbial recruitment starts in utero, something that had not been shown in any other Vertebrate class. The main goal of this project was to test whether this type of recruitment happens in a non-mammalian Vertebrate. We tested in the viviparous fish Brachyistius frenatus the hypothesis under which the uterine pouch is colonized by a microbiome transmissible to the juveniles, conferring them an ontogeny similar to Mammals. This project also aimed to i) characterize the mode of transmission of the microbiota, ii) establish the composition, diversity and relationships between the microbial communities of pregnant females, juveniles and their environment and iii) determine the ontogeny of the microbiota in B. frenatus. We characterized the mode of transmission of the microbiome, explored its recruitment and the contribution of different source communities with a metagenomic approach (bar coding). We targeted the hyper variable region V4 of the small subunit (16S) rRNA gene to determine the presence of a vertical transmission of the microbiome In this study, we confirmed the presence of a vertically transmissible microbiome in the viviparous fish B. frenatus. We documented for the first time an in utero transmission of themicrobiota in a non-mammalian viviparous species. Our results also hint that B. frenatus might be a new model of microbiota ontogeny. This study contributes to the acquisition of knowledge on microbiome transmission and, in the context of evolutionary convergence of viviparity, allows the formulation of hypotheses concerning the evolutionary advantages of in utero microbiome transmission.

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Bourlet, Thomas. "Détection, sélection et transmission de virus au niveau des muqueuses génitales : à propos de 3 modèles : virus de l'immunodéficience humaine, virus GBV-C/HGV et virus de l'hépatite C." Saint-Etienne, 2002. http://www.theses.fr/2002STET001T.

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Les travaux presentes dans notre These s'inscrivent dans la Thematique du groupe de recherche GIMAP -Groupe Immunite des Muqueuses et Agents Pathogenes-, a savoir l'etude des interactions entre HIV et la muqueuse sexuelle, principale voie de contamination de cet agent. Nous nous sommes d'abord attaches a developper des techniques sensibles et reproductibles de detection et de qualification de l' ARN de HIV-1 dans le plasma seminal et la salive et au sein de differentes fractions cellulaires du sperme. Nos resultats suggerent l'existence d'un compartiment seminal au moins chez certains hommes "a risque" presentant une charge virale seminale plus elevee que dans le sang ; cette compartimentation apparaît plus marquee au niveau salivaire ou l'efficacite des antiretroviraux semble reduite. En parrallele, nous avons participe a la mise en evidence d'un co-recepteur CXCR4 fonctionnel a la surface de cellules de Langerhans en culture monocouche. Des travaux sont en cours pour preciser le role de ces cellules epitheliales dans la secretion des virus presentant un tropisme pour le corecepteur CCR5 lors de la transmission sexuelle. Les outils moleculaires developpes pour la detection et la quantification de HIV-1 au niveau d'echantillons muqeux nous ont ensuite permis de nous interesser a la transmission du GBV-C/HGV par voie sexuelle. Nos travaux conduits a partir d'une population d'hommes infectes par HIV-1 ont ete parmi les premiers a suggerer une transmission sexuelle de GBV-C/HGV par l'etude de la prevalence des marqeurs seriques de ce virus ( ARN et anticorps anti-E2) et par la detection chez 4 sujets d'ARN viral dans le sperme ou la salive. Par ailleurs, nous nous sommes interesses au risque de transmission de HCV chez les couples dont l'homme est porteur chronique de ce virus et candidats a une procreation medicalement assistee (PMA), par la recherche de l'ARN viral dans les differents fractions seminales. La detection d'ARN de HCV dans le plasma seminal d'environ 12% d'entre eux ainsi que,de facon transitoire, dans la fraction spermatozoides de l'un d'eux, incite a une vigilance quant au risque potentiel de contamination par l'acte de PMA. Nous poursuivons ces recherches dans le cadre de l'AC-11 de l'ANRS, par un travail de standardisation de technique de detection de l'ARN de HCV dans le sperme, notamment par la coordination d'un controle de qualite multicentrique, et dans le cadre d'un PHRC dont l'objectif est de valider un algorithme decisionnel pour la prise en charge en PMA des couples sero-differents pour HCV.

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Wardrop, Elizabeth Ann. "Transmission of potato virus S by aphids." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63934.

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Bouvaine, Sophie. "Bacterial GroEL and virus transmission by aphids." Thesis, University of York, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.516604.

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Lau, Lee-hang Lincoln, and 劉力恆. "Influenza virus shedding and transmission in households." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hdl.handle.net/10722/196093.

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Background The dynamics of influenza virus transmission are not yet fully understood, hindering the appropriate development and implementation of control and mitigation strategies. One major uncertainty relates to the profile of infectiousness over time in humans infected by influenza virus, and how variation in infectiousness might contribute to the risk of transmission in households. Methods In 2008 and 2009, two large community-based studies were conducted to study the household transmission of influenza viruses in Hong Kong. I analyzed data on viral shedding and disease in participants, and used statistical models to examine how viral shedding patterns and other factors might affect the risk of influenza virus transmission in households, both within individuals over time, and between individuals with different patterns in viral shedding. Results The patterns of viral shedding relative to the time of illness (acute respiratory illness; ARI) onset in naturally acquired infections were found to be largely comparable to the patterns observed in experimental infections. Viral shedding detected by RT-PCR peaks around the day of ARI onset after which levels of shedding declined over around 7 days, and viral shedding tended to be greater in children than adults. The patterns of viral shedding in cases of seasonal A subtypes were similar, although the trends of shedding in cases of seasonal B differed with some indication of a plateau in shedding for up to 5 days after illness onset. The risk of household influenza transmission was significantly associated with log10 viral shedding, though not with influenza related signs and symptoms such as cough. Conclusions The patterns of viral shedding observed in naturally-acquired influenza A virus infections correlated with the pattern of infectiousness over time after onset of illness. The majority of infectiousness was estimated to occur within 2-3 days of illness onset, with implications for isolation strategies. The heterogeneous nature of individual viral shedding suggests the possibility of substantial variation in infectiousness, particularly among children.
published_or_final_version
Community Medicine
Doctoral
Doctor of Philosophy

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Lu, Lu. "Transmission dynamics of Avian Influenza A virus." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/10481.

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Influenza A virus (AIV) has an extremely high rate of mutation. Frequent exchanges of gene segments between different AIV (reassortment) have been responsible for major pandemics in recent human history. The presence of a wild bird reservoir maintains the threat of incursion of AIV into domestic birds, humans and other animals. In this thesis, I addressed unanswered questions of how diverse AIV subtypes (classified according to antigenicity of the two surface proteins, haemagglutinin and neuraminidase) evolve and interact among different bird populations in different parts of the world, using Bayesian phylogenetic methods with large datasets of full genome sequences. Firstly, I explored the reassortment patterns of AIV internal segments among different subtypes by quantifying evolutionary parameters including reassortment rate, evolutionary rate and selective constraint in time-resolved Bayesian tree phylogenies. A major conclusion was that reassortment rate is negatively associated with selective constraint and that infection of wild rather than domestic birds was associated with a higher reassortment rate. Secondly, I described the spatial transmission pattern of AIV in China. Clustering of related viruses in particular geographic areas and economic zones was identified from the viral phylogeographic diffusion networks. The results indicated that Central China and the Pearl River Delta are two main sources of viral out flow; while the East Coast, especially the Yangtze River delta, is the major recipient area. Simultaneously, by applying a general linear model, the predictors that have the strongest impact on viral spatial diffusion were identified, including economic (agricultural) activity, climate, and ecology. Thirdly, I determined the genetic and phylogeographic origin of a recent H7N3 highly pathogenic avian influenza outbreak in Mexico. Location, subtype, avian host species and pathogenicity were modelled as discrete traits and jointly analysed using all eight viral gene segments. The results indicated that the outbreak AIV is a novel reassortant carried by wild waterfowl from different migration flyways in North America during the time period studied. Importantly, I concluded that Mexico, and Central America in general, might be a potential hotspot for AIV reassortment events, a possibility which to date has not attracted widespread attention. Overall, the work carried out in this thesis described the evolutionary dynamics of AIV from which important conclusions regarding its epidemiological impact in both Eurasia and North America can be drawn.

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Lequime, Sébastian. "Interactions flavivirus-moustiques : diversité et transmission." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066081/document.

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Les flavivirus sont des virus à ARN parmi lesquels certains sont des arbovirus transmis entre hôtes vertébrés par des vecteurs arthropodes, notamment des moustiques. L'interaction avec les moustiques est centrale dans la biologie des flavivirus par son influence sur leur diversité génétique et transmission, mais certains de ses aspects restent méconnus. Au cœur de cette thèse, des approches basées sur les « big data », générées par des technologies modernes ou par compilation de travaux plus anciens, ont éclairé d’un jour nouveau la complexité des relations moustique-flavivirus. En explorant des génomes de moustiques anophèles, nous avons identifié et caractérisé des éléments viraux endogènes d'origine flavivirale chez Anopheles sinensis et An. minimus, suggérant l'existence de flavivirus infectant les anophèles et révélant une facette insoupçonnée de leur diversité. Par ailleurs, nous avons exploré, par séquençage haut-débit, la fine interaction entre le génotype du moustique Aedes aegypti et la diversité intra-hôte du virus de la dengue-1. Nos résultats montrent un fort effet de la dérive génétique lors de l'infection initiale, diminuant l'importance relative de la sélection naturelle, et une modulation de la diversité génétique intra-hôte du virus par le génotype du moustique. Enfin, nous avons compilé la littérature sur la transmission verticale des arbovirus chez les moustiques, c'est-à-dire de la femelle infectée à sa descendance, afin d'identifier des facteurs techniques et biologiques sous-jacents. Nos résultats améliorent la compréhension de ce mode de transmission et des stratégies employées par les arbovirus pour persister dans l’environnement
Flaviviruses are RNA virus among which some are arboviruses transmitted between vertebrate hosts and arthropod vectors, like mosquitoes. The interaction with mosquitoes is key in the biology of flaviviruses because it influences their genetic diversity and transmission. However, some aspects however are still poorly understood. At the heart of the work presented in this dissertation, strategies based on ‘big data’, both by taking advantage of modern technologies and by compiling older literature, highlighted new aspects of the complex relationships between flaviviruses and mosquitoes. While exploring Anopheles mosquito genomes, we identified and characterized endogenous viral elements of flaviviral origin in Anopheles sinensis and An. minimus, which supports the existence of flaviviruses infecting Anopheles mosquitoes and highlights new aspected of their diversity. Besides, we explored, by deep sequencing, the fine-tuned interaction between genotypes of the mosquito Aedes aegypti and the intra-host diversity of dengue virus 1. Our results showed a strong effect of genetic drift during initial infection, reducing the relative importance of natural selection, and a modulation of the intra-host viral genetic diversity by the mosquito genotype. Finally, we assembled the litterature on arbovirus vertical transmission in the mosquito vector, i.e. from an infected female to her offspring, in order to identify underlying technical and biological predictors. Our results increase our understanding of this transmission mode and the strategies employed by arboviruses to persist in their environment

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Silva, Paulo Adilson da [UNESP]. "Habilidades matemáticas e memória operacional em crianças de 7 a 12 anos infectadas pelo HIV por transmissão vertical, em estado assintomático." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/97536.

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Made available in DSpace on 2014-06-11T19:29:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-08-02Bitstream added on 2014-06-13T19:16:59Z : No. of bitstreams: 1 silva_pa_me_assis.pdf: 572416 bytes, checksum: ca6a9be38f640b2541a62154d228a67f (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
A síndrome de imunodeficiência adquirida (AIDS) é causada por infecção pelo vírus da imunodeficiência humana (HIV). No Brasil, segundo o Ministério da Saúde (2010), de 1980 a meados de 2010 foram notificados no SINAN um total de 14.926 casos (acumulados) de crianças menores de 13 anos infectadas, das quais 85,1% foram infectadas através de transmissão vertical. Em 2009, das 304 notificações de novos casos de AIDS em crianças com menos de 13 anos de idade, 92,1% dos casos foram decorrentes deste tipo de transmissão. Anormalidades encefálicas associadas à infecção pelo HIV são comuns e são as que primeiro aparecem entre crianças infectadas verticalmente. Déficits cognitivos relacionados a estas alterações estão presentes nessas crianças, contudo os estudos sobre as alterações cognitivas nessa população apresentam diversas limitações, como o pequeno tamanho da amostra, medidas inespecíficas e ausência de grupo controle. O objetivo do estudo foi avaliar o perfil de desempenho em habilidades matemáticas e memória operacional de crianças infectadas pelo HIV por transmissão vertical em idade escolar por meio de bateria de testes específicos para matemática (ZAREKI-R) e para memória operacional (AWMA), analisando se esse perfil se relaciona a aspectos como estado clinicoimunológico, carga viral, TARV e adesão, qualidade de vida e humor. Participaram do estudo 26 crianças, divididas em dois grupos, experimental (GE; N=13) e controle (GC; N=13), segundo a presença ou não da infecção pelo HIV. As crianças do grupo experimental foi composta por crianças infectadas por transmissão vertical pelo HIV, assintomáticas, de idade entre 7 e 12 anos de ambos os sexos.
Acquired Immunodeficiency Syndrome (AIDS) is caused by infection with human immunodeficiency virus (HIV). In Brazil, according to the Ministry of Health (2010), from 1980 to mid-2010 there were notified in SINAN a total of 14,926 cases (cumulative) of infected children less than 13 years, of whom 85.1% were vertically infected. In 2009, from 304 notifications of new AIDS cases in children 92.1% were due to this type of transmission. Brain abnormalities associated with HIV infection are common and the first to manifest among vertically infected children. Cognitive deficits related to these changes are present in these children, but studies on cognitive impairment in this population have several limitations, including small sample sizes, nonspecific measures and lack of control groups. The purpose of this study was to evaluate the performance of mathematic skills and working memory of school-age children infected with HIV by vertical transmission through specific battery tests for mathematics (Zareki-R) and working memory (AWMA), analyzing if this profile is related to aspects such as clinico-imunological stage, viral load, antiretroviral therapy and adherence, quality of life and humor. The study included 26 children, divided into two groups, experimental (GE, N = 13) and control (GC, N = 13), according to the presence or absence of HIV infection. The experimental group was formed by children infected with HIV by vertical transmission, in asymptomatic stage, from 7 and 12 years-old, of both genders.

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Katri, Patricia. "Modeling the Transmission Dynamics of the Dengue Virus." Scholarly Repository, 2010. http://scholarlyrepository.miami.edu/oa_dissertations/417.

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Dengue (pronounced den'guee) Fever (DF) and Dengue Hemorrhagic Fever (DHF), collectively known as "dengue," are mosquito-borne, potentially mortal, flu-like viral diseases that affect humans worldwide. Transmitted to humans by the bite of an infected mosquito, dengue is caused by any one of four serotypes, or antigen-specific viruses. In this thesis, both the spatial and temporal dynamics of dengue transmission are investigated. Different chapters present new models while building on themes of previous chapters. In Chapter 2, we explore the temporal dynamics of dengue viral transmission by presenting and analyzing an ODE model that combines an SIR human host- with a multi-stage SI mosquito vector transmission system. In the case where the juvenile populations are at carrying capacity, juvenile mosquito mortality rates are sufficiently small to be absorbed by juvenile maturation rates, and no humans die from dengue, both the analysis and numerical simulations demonstrate that an epidemic will persist if the oviposition rate is greater than the adult mosquito death rate. In Chapter 3, we present and analyze a non-autonomous, non-linear ODE system that incorporates seasonality into the modeling of the transmission of the dengue virus. We derive conditions for the existence of a threshold parameter, the basic reproductive ratio, denoting the expected number of secondary cases produced by a typically infective individual. In Chapter 4, we present and analyze a non-linear system of coupled reaction-diffusion equations modeling the virus' spatial spread. In formulating our model, we seek to establish the existence of traveling wave solutions and to calculate spread rates for the spatial dissemination of the disease. We determine that the epidemic wave speed increases as average annual, and in our case, winter, temperatures increase. In Chapter 5, we present and analyze an ODE model that incorporates two serotypes of the dengue virus and allows for the possibility of both primary and secondary infections with each serotype. We obtain an analytical expression for the basic reproductive number, R_0, that defines it as the maximum of the reproduction numbers for each strain/serotype of the virus. In each chapter, numerical simulations are conducted to support the analytical conclusions.

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Thurston, Milo. "Virus transmission dynamics and pathogenesis in Brassica species." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249332.

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Cartwirght, Ewen James. "Barley mild mosaic virus : deletions, duplication and transmission." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285557.

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Ngui, Siew Lin. "Molecular analysis of hepatitis B virus transmission events." Thesis, University College London (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299915.

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VILAR-COUCE, CAROLINA VIDA. "Transmission heterosexuelle du vih (virus de l'immunodeficience humaine)." Aix-Marseille 2, 1990. http://www.theses.fr/1990AIX20188.

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Núñez, García Ana Isabel. "Influence of mosquito-virus interaction on Zika virus and Rift Valley fever phlebovirus transmission." Doctoral thesis, Universitat Autònoma de Barcelona, 2020. http://hdl.handle.net/10803/670697.

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Les malalties transmeses per vectors representen un alt percentatge de les malalties infeccioses en el món. Concretament, les malalties causades per arbovirus (arthropod-born viruses), que circulen en la naturalesa entre artròpodes (els seus vectors), i els hostes vertebrats (els seus reservorios), poden causar malalties greus en els hostes vertebrats, però no causen una patologia significativa en els vectors. Durant dècades les malalties causades per arbovirus van ser oblidades, ja que en la seva gran majoria estaven localitzades en zones en vies de desenvolupament. En l'actualitat, factors ambientals, ecològics i socioeconòmics, com el canvi climàtic i la globalització, han contribuït a l'emergència i reemergencia de les malalties arbovirales. El constant moviment de persones i mercaderies ha donat lloc a la colonització i establiment d'espècies d'exòtiques al nostre país, com el mosquit tigre (Aedes albopictus), el qual és transmissor de molts arbovirus (e.g. el virus del dengue, el virus Zika (ZIKV) o el virus chikungunya). El desenvolupament d'aquesta tesi es va centrar en realitzar estudis de competència vectorial per al ZIKV i en un estudi del transcriptoma de Culex pipiens després de ser exposat al phlebovirus de la febre de la Vall del Rift (RVFV) per a comprendre les interaccions el virus i els mosquits locals. Els capítols I i II es van focalitzar a estimar la competència vectorial per a ZIKV de diferents espècies de mosquits de camp presents al nostre país: Aedes albopictus, Aedes caspius i Culex pipiens. A més, es van desenvolupar experiments de transmissió vertical per a determinar si la generació de mosquits provinents de femelles infectades amb el ZIKV és capaç de disseminar-ho. Durant el desenvolupament d'aquests estudis, s'ha demostrat que els mosquits locals de l'espècie Ae. albopictus són vectors competents per al ZIKV. No obstant això, les espècies Cx. pipiens i Ae. caspius són refractàries per a aquest arbovirus. Respecte a l'experiment de transmissió vertical, es va demostrar que la progènie de les femelles inoculades amb el virus de manera intratoràcica va ser susceptible a la infecció del virus, però no van ser capaços de disseminar-lo. D'altra banda, el capítol III es va centrar en l'estudi de les interaccions a nivell molecular entre l'espècie de mosquit Cx. pipiens i RVFV, amb l'objectiu caracteritzar les alteracions a nivell molecular de l'expressió dels gens corresponents al sistema immune del mosquit durant la infecció per RVFV mitjançant una anàlisi del transcriptoma de novo. Com a resultat, es van obtenir 48 gens diferencialment expressats en els mosquits davant la presència del virus que servir de diana per a controlar la infecció, ja sigui per a desequilibrar la tolerància dels mosquits al virus com per a inhibir la infecció en els mosquits. Els resultats obtinguts de l'estudi de les alteracions del transcriptoma de mosquits de l'espècie Cx. pipiens exposats a RVFV estableixen les bases per a la realització de futurs estudis funcionals dels gens involucrats a controlar/permetre la infecció per RVFV. En el seu conjunt, el desenvolupament d'aquesta tesi incrementa el coneixement per a millorar el disseny d'estratègies eficients per a la vigilància de vectors transmissors del ZIKV i del RVFV.
Las enfermedades transmitidas por vectores representan un alto porcentaje de las enfermedades infecciosas en el mundo. Concretamente, las enfermedades causadas por arbovirus (arthropod-borne viruses), que circulan en la naturaleza entre artrópodos (sus vectores), y los hospedadores vertebrados (sus reservorios), pueden causar enfermedades graves en los hospedadores vertebrados, pero no causan una patología significativa en los vectores. Durante décadas las enfermedades causadas por arbovirus fueron olvidadas, ya que en su gran mayoría estaban localizadas en zonas en vías de desarrollo. En la actualidad, factores ambientales, ecológicos y socioeconómicos, como el cambio climático y la globalización, han contribuido a la emergencia y reemergencia de las enfermedades arbovirales. El constante movimiento de personas y mercancías ha dado lugar a la colonización y establecimiento de especies de exóticas en nuestro país, como el mosquito tigre (Aedes albopictus), el cual es transmisor de muchos arbovirus (e.g. el virus del dengue, el virus Zika (ZIKV) o el virus chikungunya). El desarrollo de esta tesis se centró en realizar estudios de competencia vectorial para el ZIKV y en un estudio del transcriptoma de Culex pipiens después de ser expuesto al phlebovirus de la fiebre del Valle del Rift (RVFV) para comprender las interacciones el virus y los mosquitos locales. Los capítulos I y II se focalizaron en estimar la competencia vectorial para ZIKV de diferentes especies de mosquitos de campo presentes en nuestro país: Aedes albopictus, Aedes caspius y Culex pipiens. Además, se desarrollaron experimentos de transmisión vertical para determinar si la generación de mosquitos provenientes de hembras infectadas con el ZIKV es capaz de diseminarlo. Durante el desarrollo de estos estudios, se ha demostrado que los mosquitos locales de la especie Ae. albopictus son vectores competentes para el ZIKV. Sin embargo, las especies Cx. pipiens y Ae. caspius son refractarias para este arbovirus. Con respecto al experimento de transmisión vertical, se demostró que la progenie de las hembras inoculadas con el virus de forma intratorácica fue susceptible a la infección del virus, pero no fueron capaces de diseminarlo. Por otro lado, el capítulo III se centró en el estudio de las interacciones a nivel molecular entre la especie de mosquito Cx. pipiens y RVFV, con el objetivo caracterizar las alteraciones a nivel molecular de la expresión de los genes correspondientes al sistema inmune del mosquito durante la infección por RVFV mediante un análisis del transcriptoma de novo. Como resultado, se obtuvieron 48 genes diferencialmente expresados en los mosquitos ante la presencia del virus que servir de diana para controlar la infección, ya sea para desequilibrar la tolerancia de los mosquitos al virus como para inhibir la infección en los mosquitos. Los resultados obtenidos del estudio de las alteraciones del transcriptoma de mosquitos de la especie Cx. pipiens expuestos a RVFV sientan las bases para la realización de futuros estudios funcionales de los genes involucrados en controlar/permitir la infección por RVFV. En conjunto, el desarrollo de esta tesis incrementa el conocimiento para mejorar el diseño de estrategias eficientes para la vigilancia de vectores transmisores del ZIKV y del RVFV.
Vector-borne diseases represent a 17 % of infectious diseases in the world. Among them, those diseases caused by arboviruses (arthropod-borne viruses), which circulate in the nature between arthropods (their vectors) and vertebrate hosts (their reservoirs), are currently provoking serious diseases in humans and animals. For decades, the arboviral diseases were neglected, since most of them were located in developing areas. Nowadays, environmental, ecological and socioeconomic factors (e.g., globalization and climate change) have contributed to the emergence and re-emergence of arboviral diseases. The constant movement of people and merchandise has allowed the colonization and establishment of exotic mosquito species in our country such as the tiger mosquito (Aedes albopictus), which is a potential vector of many arboviruses (e.g., dengue virus, Zika virus or chikungunya virus). This thesis focused on conducting vector competence and transmission studies in local mosquito species for Zika virus (ZIKV) and on the study of the Culex pipiens transcriptome alteration after being exposed to the Rift Valley fever phlebovirus (RVFV) in order to better understand how virus-vector interaction influences on ZIKV and RVFV transmission. Chapters I and II focused on estimating the vector competence for ZIKV of different field-collected mosquito species present in our country: Aedes albopictus, Aedes caspius and Culex pipiens. In addition, vertical transmission studies were performed to determine if the progeny of females infected with ZIKV were able to disseminate the virus. The results of these studies showed that local populations of Ae. albopictus were competent vectors for ZIKV and Cx. pipiens and Ae. caspius species were refractory for this arbovirus. Moreover, it was demonstrated that ZIKV was able to be transmitted to the progeny but the later could not disseminate the virus. Chapter III focused on the study of interactions between the Cx. pipiens mosquito species and RVFV at molecular level, with the aim to characterize the alterations in the expression of the mosquito genes related to the immune system during RVFV infection by analyzing de novo transcriptome. As a result, 48 immune differentially expressed genes in mosquitoes exposed to RVFV were altered, which could serve as potential targets to control the infection, either by unbalancing the mosquito tolerance to RVFV or by inhibiting the infection in mosquitoes. The results obtained on the Cx. pipiens transcriptome alterations due to exposure to RVFV pave the way for future functional studies about genes involved in the control/tolerance of RVFV infection. Overall, this thesis increased the knowledge to better design efficient strategies for ZIKV and RVFV surveillance and control.

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Pereira, de Oliveira Rémi. "Mécanismes de transmission vectorielle du virus de la Peste Porcine Africaine et facteurs influençant cette transmission : étude de différentes associations tique-virus." Thesis, Montpellier, 2020. http://www.theses.fr/2020MONTG013.

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Aucun vaccin n’est actuellement disponible pour lutter contre la Peste Porcine Africaine (PPA), une des maladies les plus graves des suidés, faisant des ravages en Afrique, en Europe et en Asie. Pour combattre cette maladie infectieuse causée par le virus de la PPA (vPPA), la compréhension des différents modes de transmission est essentielle pour appliquer des mesures sanitaires adéquates. Un des modes de transmission est la piqûre de tiques infectées. L’objectif de ma thèse était de comprendre les mécanismes et les facteurs qui déterminent la compétence vectorielle des tiques molles Ornithodoros pour le vPPA. Ce travail de thèse a tout d’abord permis de montrer que les tiques présentes en Europe n’étaient pas compétentes pour les souches circulant actuellement en Eurasie, mais qu’elles pouvaient maintenir le virus infectieux pendant plusieurs mois et être infectantes pour les porcs par ingestion. Cette étude a également permis de mettre en évidence, qu’outre la dissémination du vPPA chez la tique jusqu’aux organes de transmission, le niveau de réplication virale était un facteur essentiel à la transmission. Toutefois, nos résultats suggèrent d’autres déterminants, encore inconnus, qui tendent à moduler chacune de ces étapes. Une analyse comparative de deux génomes de vPPA aux profils de transmission différents a ainsi montré quelques différences génétiques qui peut représenter une piste pour la compréhension des facteurs génétiques contribuant à déterminer la compétence vectorielle. En outre, une étude préliminaire menée au cours de cette thèse a montré que l’infection de la tique par le vPPA induisait une modulation de certains peptides antimicrobiens, mettant en lumière l’existence d’interactions moléculaires entre la tique et le vPPA. Les résultats obtenus ont été discuté au regard des risques potentiels à l’établissement d’un cycle de transmission entre tique et suidés et de la mise en place de mesures sanitaires adaptées à ces zones au contexte épidémiologique particulier
There is currently no vaccine available to control African Swine Fever (ASF), one of the most important swine diseases that ravages Africa, Europe and Asia. To fight the ASF virus (ASFV) that induces infectious disease, understanding the different modes of transmission is essential to apply adequate sanitary measures. One mode of transmission is through the bite of an infected tick. The main objective of my thesis was to understand the mechanisms and factors that determine the vectorial competence of the Ornithodoros soft ticks for ASFV. First, this thesis project showed that the ticks present in Europe are not competent for the strains currently circulating in Eurasia, but can maintain the virus for several months and be infectious to pigs, at least by ingestion. This study also showed that dissemination of ASFV inside ticks towards transmission organs is not enough and must be completed by a sufficient level of viral replication to allow transmission. However, our results also suggest the existence of other factors, partially unknown, that modulate each of these stages. A comparative analysis of two ASFV genomes with different vectorial transmission patterns showed several genetic differences, which may contribute to determining vector competence. In addition, a preliminary study conducted in this PhD project demonstrated that the infection of ticks with ASFV induced modulation of some antimicrobial peptides, highlighting that there is an interaction at the molecular level between the tick and the ASFV. All these results were discussed in regard to potential risks for the establishment of a tick-suid transmission cycle and the implementation of appropriate sanitary measures in these peculiar areas

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Fournès, Florian. "Etude du système Xer au travers de la transmission verticale et horizontale de l'information génétique chez les bactéries." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30143/document.

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Les génomes bactériens sont le siège de deux phénomènes de transferts de l'information génétique: les transferts verticaux et horizontaux. Leur coéxistence ce qui implique une délicate balance entre maintenance et instabilité des génomes. L'information génétique des bactéries est généralement portée par des réplicons circulaires : chromosomes et plasmides. Un des sérieux désavantages des réplicons circulaires est leur grande sensibilité aux réarrangements causés par recombinaison homologue. Un nombre impair de crossing-over pendant ou après la réplication de ces réplicons entraine la formation de molécules dimériques. Ces dimères correspondent à une fusion covalente des deux copies du réplicon, non-résolus les dimères ne ségrégeront pas correctement au moment de la division cellulaire. La résolution des formes multimériques des plasmides et chromosomes circulaires est médiée par un mécanisme de recombinaison spécifique de site efficace et extrêmement contrôlé : le système Xer. Les mécanismes de résolution des dimères de chromosome et de plasmide sont différents. De plus, bien que le système de résolution de dimères de chromosome soit contrôlé dans le temps et dans l'espace, chez de nombreuses bactéries il est détourné de son rôle principal par des éléments génétiques mobiles appelés IMEXs (Integrative Mobile Elements exploiting Xer). Le système Xer est alors impliqué dans les transferts verticaux et horizontaux de gènes, illustrant comment une même machine moléculaire peut intervenir dans plusieurs processus biologiques. Pour cela, des acteurs externes différents vont jouer un rôle clé dans le contrôle d'une machine Xer centrale et ainsi apporter une diversité de mécanismes, chacun dédié à une processus biologique propre. Afin de mieux comprendre les contrôles différentiels du système Xer, je me suis intéressé aux éléments génétiques mobiles. Via l'étude de la stabilité intra-chromosomique des IMEXs et de la résolution des dimères de certains grands plasmides, j'ai pu montrer que FtsK, la protéine activatrice de la résolution des dimères de chromosome, est impliquée dans la stabilisation des éléments acquis par transferts horizontaux de gènes
The genetic information of bacteria is generally carried by circular replicons: chromosomes and plasmids. One of the serious disadvantages of circular replicons is their high sensitivity to rearrangements caused by homologous recombination. An odd number of crossing-over, during or after the replication of these replicons, results in the formation of dimeric molecules. These dimers correspond to a covalent fusion between the two copies of the replicon. If they are not resolved, the dimers will not segregate properly at the time of cell division. The resolution of multimeric forms of circular plasmids and chromosomes is mediated by an efficient and highly controlled site-specific recombination mechanism: the Xer system. The mechanisms of resolution of the chromosome and plasmid dimers are different. In addition, even if the chromosome dimer resolution system is controlled in time and space, in many bacteria it is hijacked by mobile genetic elements called IMEXs (Integrative Mobile Elements Exploiting Xer). The Xer system is then involved in the vertical and horizontal transfer of genes, illustrating how the same molecular machine can intervene in several biological processes. For this, different external actors will play a key role in controlling a central Xer machine and thus bring a variety of mechanisms, each dedicated to a specific biological process. In order to better understand the differential controls of the Xer system, I focused on mobile genetic elements. By studying the intra-chromosomal stability of IMEXs and the resolution of large plasmids dimers, I was able to show that FtsK is involved in the stabilization of the acquired mobile genetic elements

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48

Hamdollah-Zadeh, Akram. "Transgenic resistance to pollen transmission of tobacco ringspot virus." Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364912.

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Yang, Wan. "Airborne Transmission of Influenza a Virus in Indoor Environments." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/77340.

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Abstract:

Despite formidable advances in virology and medicine in recent decades, we know remarkably little about the dynamics of the influenza virus in the environment during transmission between hosts. There is still controversy over the relative importance of various transmission routes, and the seasonality of influenza remains unexplained. This work focuses on developing new knowledge about influenza transmission via the airborne route and the virus' inter-host dynamics in droplets and aerosols. We measured airborne concentrations of influenza A viruses (IAVs) and size distributions of their carrier aerosols in a health center, a daycare center, and airplanes. Results indicate that the majority of viruses are associated with aerosols smaller than 2.5 µm and that concentrations are sufficient to induce infection. We further modeled the fate and transport of IAV-laden droplets expelled from a cough into a room, as a function of relative humidity (RH) and droplet size. The model shows that airborne concentrations of infectious IAV vary with RH through its influence on virus inactivation and droplet size, which shrinks due to evaporation. IAVs associated with large droplets are removed mostly by settling, while those associated with aerosols smaller than 5 µm are removed mainly by ventilation and inactivation. To investigate the relationship between RH and influenza transmission further, we measured the viability of IAV in droplets at varying RHs. Results suggest that there exist three regimes defined by RH: physiological conditions (~100% RH) with high viability, concentrated conditions (~50% to ~99% RH) with lower viability, and dry conditions (<~50% RH) with high viability. A droplet's extent of evaporation, which is determined by RH, affects solute concentrations in the droplet, and these appear to influence viability. This research considerably advances the current understanding of the dynamics of the influenza virus while it is airborne and provides an explanation for influenza's seasonality. Increased influenza activity in winter in temperate regions could be due to greater potential for IAV carrier aerosols to remain airborne and higher viability of IAV at low RH. In tropical regions, transmission could be enhanced due to better survival of IAV at extremely high RH.
Ph. D.

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Bichaud, Laurence. "Emerging phleboviruses around Mediterranean : epidemiology, virus discovery, and human transmission aspect." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM5007.

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Les phlébotomes sont les vecteurs reconnus de plusieurs arbovirus, en particulier du genre Phlebovirus, ainsi que de parasites du genre Leishmania. Les infections par les phlébovirus sont responsables chez l’homme de maladies décrites depuis longtemps, pourtant ils demeurent méconnus, avec en particulier un manque de données épidémiologiques et d’outils de diagnostic.Dans une première partie, des études de séroprévalence nous ont permis d’aborder l’impact en santé publique, dans le sud-est de la France, de deux phlébovirus connus pour leur pouvoir pathogène chez l’homme, Toscana virus (TOSV) et Sandfly fever Sicilian virus (SFSV). Pour ce dernier, des anticorps spécifiques (IgG) ont été détectés dans moins de 1% des sérums testés, ce qui suggère que SFSV joue un rôle mineur dans les pathologies humaines de cette région ; ces résultats sont corroborés par l’absence, durant ces dernières décennies, de cas documentés d’infection aigüe due à SFSV en Europe occidentale. Nous avons donc pu concentrer notre travail sur le deuxième groupe de phlébovirus d’intérêt chez l’homme, le groupe des Sandfly fever Naples virus, qui inclut notamment TOSV. Nous avons démontré l’existence d’un lien épidémiologique entre les infections à Leishmania infantum et celles à TOSV, certainement dû au fait que ces pathogènes sont transmis par un vecteur commun (Phlebotomus perniciosus). Les analyses statistiques ont montré que les personnes exposées aux infections à TOSV ont plus de chance d’être aussi infectées par les parasites leishmanies (et vice versa). En admettant que ce lien épidémiologique entre leishmanioses et infections à TOSV est représenté par l’exposition à la piqûre d’un vecteur commun, cette étude confirme l’implication de Phlebotomus perniciosus en tant que vecteur principal de TOSV dans le sud de la France. Cette étude suggère également que certaines données épidémiologiques disponibles pour la leishmaniose pourraient être utilisées pour décrypter l’épidémiologie des infections à TOSV.La deuxième partie de cette thèse est consacrée à la détection, l’isolement et la caractérisation de virus, déjà connus ou inconnus, dans les populations de phlébotomes en France et en Afrique du Nord. Pour atteindre cet objectif, nous avons dû développer une plateforme d’analyse à au débit, adaptée pour la découverte de virus dans les phlébotomes, qui permette de traiter un grand nombre d’échantillons à faible coût. Cette plateforme a récemment été complétée par un outil de Next Generation Sequencing, afin de réaliser la caractérisation génétique complète des virus isolés et découverts. Au total, 12 576 phlébotomes ont été capturés au cours de 12 campagnes de capture menées en France, en Tunisie et en Algérie. Au sein d’une même zone géographique, la découverte de plusieurs nouveaux phlébovirus, ainsi que leur taux d’infection observé dans les populations de phlébotomes, ont démontré que la diversité de phlebovirus est bien plus importante qu’attendue.Dans la troisième partie de cette thèse, une étude de séroprévalence a été menée sur des sérums humains en utilisant des tests comparatifs de neutralisation de virus. Cette étude nous a permis d’exclure le virus Punique, récemment découvert, de la liste des principales menaces en santé publique au nord de la Tunisie, et de confirmer que TOSV est le principal phlebovirus pathogène ayant un impact en santé publique dans cette région du pays. Cette méthode de neutralisation est capable d’identifier précisément, parmi des virus génétiquement proches, le virus contre lequel les anticorps présents dans le sang ont été produits, ce qui permet de déterminer la capacité de chacun de ces virus à jouer un rôle en santé publique
Sandflies are vectors of various arthropod-borne viruses, in particular viruses within the genus Phlebovirus, family Bunyaviridae, and of parasites in the genus Leishmania. Human diseases caused by infection with sandfly-borne phleboviruses are known for a long time, but they remain neglected due to the lack of epidemiological knowledge and of diagnostic tools.The first part consisted of seroprevalence studies in human sera to address the public health impact in south-eastern France of two recognized sandfly-borne phleboviruses, namely Toscana virus (TOSV) and Sandfly fever Sicilian virus (SFSV). Concerning the latter, specific IgG were detected in less than 1% of tested sera, suggesting that SFSV play a minor role in human disease in the region; this finding was corroborated with the lack of documented case of acute infection due to SFSV in Western Europe during the last decade. This pleaded for focusing on the other group of sandfly fever viruses known for their human interest, namely the group of Sandfly fever Naples virus that includes TOSV. We demonstrated an existing epidemiological relationship between Leishmania infantum and TOSV infections, presumably through the transmission by the common arthropod vector (Phlebotomus perniciosus). Statistical analysis showed that persons exposed to TOSV infection are at greater risk of being infected with Leishmania parasite (and vice versa). Assuming that epidemiological link between leishmaniasis and TOSV infection may be represented by the exposure to the bite of a common vector, this study confirms the involvement of Phlebotomus perniciosus as the major vector of TOSV in the South of France. This study also suggests that some of the epidemiological data available on Leishmaniasis may be used to decipher the epidemiology of TOSV infections..The second part of this thesis was dedicated to detection, isolation and characterization of existing and/or new phleboviruses in sandfly populations in France and in North Africa. To achieve this aim, we had to set up a high-throughput cost-effective platform amenable to virus discovery in sandflies; this sandfly-processing platform has been recently docked to a Next Generation Sequencing platform for full genetic characterization of newly isolated and discovered viruses. A total of 12,576 sandflies were trapped during 12 campaigns conducted in France, Tunisia and Algeria. The discovery of several new phleboviruses and their observed frequency in sandfly populations has clearly demonstrated that within a given geographic area, virus diversity is much higher than previously believed.In the third part of this thesis, a seroprevalence study based on comparative virus neutralization tests was performed on human sera and allowed to exclude the newly described Punique virus from the list of major public health threats in northern Tunisia, and to confirm that TOSV is the dominant phleboviral pathogen with an impact on public health in this part of the country. This neutralization method is suitable to identify precisely the virus against which antibodues were elicited, allowing to discriminate among closely related phleboviruses, and to determine their propensity to play a role in public health

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Dissertations / Theses on the topic 'Virus à transmission verticale'

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