Articoli di riviste: "Survival of lawsonia intracellularis"

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Pereira, Carlos Eduardo Real, Talita Pilar Resende, Aníbal G. Armién, Ricardo Pereira Laub, Fabio Augusto Vannucci, Renato Lima Santos, Connie Jane Gebhart e Roberto Mauricio Carvalho Guedes. "Survival of Lawsonia intracellularis in porcine peripheral blood monocyte-derived macrophages". PLOS ONE 15, n. 7 (31 luglio 2020): e0236887. http://dx.doi.org/10.1371/journal.pone.0236887.

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Garkusha, S. E., e J. O. Prodoljak. "МАКРОСКОПІЧНІ ЗМІНИ ПРИ ПРОЛІФЕРАТИВНІЙ ЕНТЕРОПАТІЇ СВИНЕЙ". Scientific Messenger of LNU of Veterinary Medicine and Biotechnology 18, n. 3(70) (9 agosto 2016): 33–36. http://dx.doi.org/10.15421/nvlvet7008.

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Infectious diseases cause significant economic damage to the industry and one such disease is proliferative enteropathy.So scientists have estimated that, for example, in Australia, the losses amount to dollars 20 per 1 pig, and in the United States losses from proliferative enteropathy in pigs was dollars 20 million annually.Symptoms and signs of the disease are known to scientists for a long time. But only in 1974, scientists discovered a bacterium that multiplies rapidly abnormally in the cells, it has been called Lawsonia intracellularis. And it is proved that it is the causative agent of the disease, in 1993.Recently we discovered that the infection in pig farms tend to widespread. According to the results of serological tests in different countries of Lawsonia intracellularis it is 60 – 90% of the herd of swine. Other authors have reported that around the world are infected with this microorganism is from 30% to 100% of herds of pigs. Serological studies have established that Lawsonia intracellularis in the United States recorded in 96% of the herd of swine. This is facilitated by the low infectious dose of pathogen isolation from faeces of a large number of bacteria, sustained release of the pathogen in the faeces and survival of Lawsonia Intracellularis in the environment for at least 2 weeks.In our state proliferative enteropathy pigs hardly been studied. In Ukraine, proliferative enteropathy pigs was detected in 15 pig farms 7 areas. In Russia, the disease is called a new and poorly understood, but some scientists call it lavsoniosis.Therefore the aim of this study was to examine in more detail the macroscopic changes at proliferative enteropathy pigs.To achieve this goal the following objectives: to conduct mortem examination of dead pigs of proliferative enteropathy, examine macroscopic changes in the internal organs of the disease, and a detailed description of the macroscopic changes in the internal organs, which they were not previously documented.The material for the study were 10 corpses of pigs killed by proliferative enteropathy. Mortem examination was carried out in spinal position by partial evisceration in a common sequence at the Department of Pathological Anatomy of the National University of Life and Environmental Sciences of Ukraine.At postmortem macroscopic changes at autopsy proliferative enteropathy in pigs were the following: thickening of the walls of the caudal part of the jejunum, ileum, cecum and colon intestine, which was accompanied by a distinct narrowing of the lumen. Swollen lymph nodes were recorded hemorrhagic thin, blind and colon. In mild venous congestion and edema and dilation of the heart and congestive hyperemia of the liver.

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Tokach, Mike D., Jordan T. Gebhardt, Steve S. Dritz, Jason C. Woodworth, Joel M. DeRouchey e Robert D. Goodband. "394 Opportunities to enhance wean-to-finish pig survival". Journal of Animal Science 98, Supplement_4 (3 novembre 2020): 184. http://dx.doi.org/10.1093/jas/skaa278.339.

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Abstract Swine productivity as measured by total pigs born, growth rate, and efficiency has improved steadily over the last few decades. However, post-weaning mortality has not improved for several years. Estimates for post-weaning mortality are 3.6% for nursery, 4.1% for grow-finish, and 5.6% of pigs entering the wean-finish phase (USDA, 2015). The first step in improving wean-to-finish survival is to understand major causes. Post-weaning mortality can be categorized into non-infectious and infectious causes. Non-infectious factors can be classified into anatomic abnormalities, toxicity, animal factors, facility factors, nutritional inadequacies, season, and management factors. Important non-infectious mortality factors identified through literature review include birth weight, preweaning management, weaning age and weight, and season. Additionally, a low incidence but high consequence cause for individual pigs is abdominal organ torsion. Sodium ion or ionophore toxicosis or dietary imbalance due to feed formulation or manufacture error are infrequent, but can be high magnitude. Infectious factors can be categorized as respiratory disease caused by swine influenza virus, porcine reproductive and respiratory syndrome virus, Mycoplasma spp., Glasserella parasuis, and others; enteric disease caused by Lawsonia intracellularis, Brachyspira spp; or systemic disease caused by Erysipelothrix rhusiopathiae, Streptococcus suis, porcine circovirus, and others. Non-infectious and infectious mortality causes both need focus to improve wean-to-finish survival. Because of their importance in affecting survival rate, producers should focus on increasing birth and weaning weight, colostrum intake, and weaning age. Strategies to reduce abdominal organ torsions and gastric ulcers also are important for producers experiencing problems with these low frequency, high magnitude problems. Elevating biosecurity to prevent introduction of pathogens can reduce mortality due to infectious agents. For pathogens already present in the herd, producers must determine if the best management strategy is control (ex. vaccination), elimination (ex. mass exposure), or depopulation. Reducing post-weaning mortality remains an opportunity area in the swine industry.

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Gabler, Nicholas K. "207 Awardee Talk: The Impact of Disease on Nutrient and Energy Intake and Utilization to Support Lean Tissue Accretion in Growing Pigs". Journal of Animal Science 100, Supplement_3 (21 settembre 2022): 93–94. http://dx.doi.org/10.1093/jas/skac247.183.

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Abstract Optimal lean tissue production can be severely compromised by health challenges in nursery-finisher pig production systems. Common pig immune challenges in the U.S. can come from pathogens such as Porcine Reproductive and Respiratory Syndrome virus, Lawsonia intracellularis, Mycoplasma spp, Coccidia, pathogenic E. coli and Porcine Epidemic Diarrhea virus. The subsequent disease that can manifests in response to these pathogens can lead to mitochondrial damage, impaired capacity to generate sufficient ATP for homeostasis, limited energy availability (exacerbated by disease hypophagia) and compromised cell survival and organ function. Collectively, skeletal muscle hypertrophy is reduced in a trade off to support the energetic and protein synthesis needs of immune system response. In growing pigs, we have reported that sub-clinical and clinical enteric and respiratory disease can significantly impact intestinal function, feed intake, lean tissue accretion and feed efficiency. This has a major economic impact for pork producers, pig welfare and wellbeing. While significant advances in molecular and quantitative genetics, clinical diagnostics and virology have been made to enhance poor performance and heath, we are still unsure on how to best feed and manage poor-health pigs. By understanding the longitudinal impact pathogens on digestibility, metabolism, protein accretion and feed efficiency, insights into nutritional requirements and management strategies can be developed to improve poor-health pig production. This paper will discuss the molecular and physiological impact of sub-clinical and clinical disease on nutrient and energy intake and utilization to support lean tissue accretion in growing pigs.

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Nathues, H., R. Tegeler e E. große Beilage. "Diagnostik in einem Mastschweinebestand mit Diarrhö". Tierärztliche Praxis Ausgabe G: Großtiere / Nutztiere 35, n. 02 (2007): 133–36. http://dx.doi.org/10.1055/s-0038-1624014.

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Zusammenfassung: Gegenstand und Ziel: In einem Mastbestand trat in einer Gruppe von etwa 200 Läuferschweinen bei 15–20% der Tiere Diarrhö auf. In einer ersten Untersuchung von zwei Analtupfern auf darmpathogene Infektionserreger konnte die Ätiologie nicht geklärt werden. Material und Methoden: Zehn Kotproben wurden mittels einer Multiplex-PCR auf spezifische Genomfragmente von Lawsonia intracellularis, Brachyspira (B.) hyodysenteriae und B. pilosicoli untersucht. Der Gehalt an Salmonella spp. und hämolysierenden Escherichia coli wurde mittels bakteriologischer Standardverfahren geprüft. Ergebnisse: In vier von zehn Kotproben konnte Lawsonia intracellularis nachgewiesen werden. Andere Enteritiserreger wurden nicht detektiert. Schlussfolgerung: Die Diarrhö im Mastbestand konnte auf eine Infektion mit Lawsonia intracellularis zurückgeführt werden. Klinische Relevanz: Zum Nachweis einer Infektionskrankheit in Herden muss stets eine ausreichende Anzahl Tiere untersucht werden. Für den Nachweis von Lawsonia intracellularis mittels PCR eignen sich Kot- und Schleimhautproben; Analtupfer sind ungeeignet.

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Visscher, Christian, Jasmin Mischok, Saara Sander, Jutta Verspohl, Eva-Ursula Peitzmeier, Isabel von dem Busche e Josef Kamphues. "Spread of an Experimental Salmonella Derby Infection in Antibiotic-Treated or Lawsonia intracellularis Vaccinated Piglets". Animals 8, n. 11 (12 novembre 2018): 206. http://dx.doi.org/10.3390/ani8110206.

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Lawsonia intracellularis infections are a common reason for antibiotic treatment in pig production. Experimental studies in animals naturally infected with Lawsonia intracellularis comparing the course of an experimental Salmonella infection in piglets previously treated with tylosin or vaccinated against Lawsonia intracellularis are scarce. A total of 72 seven-week-old Salmonella-free pigs were taken from a herd with a Lawsonia intracellularis history in piglet rearing. The pigs were divided into two groups with three replicates each. Animals had either been previously treated with tylosin (10 mg/kg body weight) for seven days (AB+VAC−) or had been vaccinated as suckling pigs by drenching (Enterisol®Ileitis; AB−VAC+). Two animals per replicate were primarily infected with Salmonella Derby (1.04 × 108 colony-forming units per animal). The detection of Salmonella in faeces (p < 0.0001, odds ratio: 3.8364) and in the ileocaecal lymph nodes (p = 0.0295, odds ratio: 3.5043) was significantly more frequent in AB+VAC− animals. Overall, the odds ratio for detecting Salmonella in any substrate or organ was significantly higher in the AB+VAC− group animals (p = 0.0004, odds ratio: 5.9091). Treatment with tylosin can significantly increase the spread of a Salmonella infection, which is not observed after early Lawsonia intracellularis vaccination.

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McCluskey, Jackie, Joanne Hannigan, Jennifer D. Harris, Brendan Wren e David G. E. Smith. "LsaA, an Antigen Involved in Cell Attachment and Invasion, Is Expressed by Lawsonia intracellularis during Infection In Vitro and In Vivo". Infection and Immunity 70, n. 6 (giugno 2002): 2899–907. http://dx.doi.org/10.1128/iai.70.6.2899-2907.2002.

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ABSTRACT Lawsonia intracellularis has been identified recently as the etiological agent of proliferative enteropathies, which are characterized by intestinal epithelial hyperplasia and associated moderate immune responses. This disease complex has been reported in a broad range of animals, prevalently in pigs, and L. intracellularis has been linked with ulcerative colitis in humans. L. intracellularis is an obligate intracellular bacterium, and the pathogenic mechanisms used to cause disease are unknown. Using in vitro-grown organisms as a source of genomic DNA, we identified a Lawsonia gene which encodes a surface antigen, LsaA (for Lawsonia surface antigen), associated with attachment to and entry into cells. The deduced amino acid sequence of this protein showed some similarity to members of a novel protein family identified in a number of other bacterial pathogens but for which roles are not fully defined. Transcription of this gene was detected by reverse transcription-PCR in L. intracellularis grown in vitro in IEC18 cells and in bacteria present in ileal tissue from infected animals. Immunohistochemistry with specific monoclonal antibody and immunoblotting with sera from infected animals demonstrated that LsaA protein is synthesized by L. intracellularis during infection. Expression of this gene during infection in vitro and in vivo suggests that this surface antigen is involved during infection, and phenotypic analysis indicated a role during L. intracellularis attachment to and entry into intestinal epithelial cells

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Page, Allen E., Nathan M. Slovis e David W. Horohov. "Lawsonia intracellularis and Equine Proliferative Enteropathy". Veterinary Clinics of North America: Equine Practice 30, n. 3 (dicembre 2014): 641–58. http://dx.doi.org/10.1016/j.cveq.2014.08.001.

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C Rodríguez-Buenfil, Jorge, Mario J Alvarez-Fleites e Rafael M Gómez-Medina. "Identificación de Lawsonia intracellularis en 20 granjas porcinas del estado de Yucatán". REVISTA BIOMÉDICA 11, n. 4 (1 ottobre 2000): 271–75. http://dx.doi.org/10.32776/revbiomed.v11i4.244.

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Introducción. La Enteropatía Proliferativa Porcina es una enfermedad emergente a nivel mundial, causada por una bacteria intracelular recientemente denominada Lawsonia intracellularis. Esta bacteria afecta a todos los cerdos observandose una mayor frecuencia en la población de engorda. En Yucatán no existe información sobre la presencia y distribución de esta enfermedad. Objetivo. Detectar la presencia de Lawsonia intracellularis en cerdos de engorda de granjas porcícolas del estado de Yucatán. Material y Métodos. Se trabajó un total de 20 granjas porcícolas las cuales fueron seleccionadas por conveniencia. Diez unidades de muestreo fueron seleccionadas de cada granja buscando la representatividad y considerando una prevalencia del 25% un nivel de confianza de 95% y una población promedio de 2000 animales. Cada unidad fue conformada recolectando heces de 4 animales de entre 30 y 90 Kg. La técnica diagnóstica que se utilizó en el laboratorio fue la de reacción en cadena de la polimerasa. Resultados. De un total de 20 granjas estudiadas 8 resultaron positivas a la presencia de Lawsonia intracellularis en la población de engorda. Esto representa un 40% de granjas infectadas con prevalencias ≥ al 25%. Con respecto al total de unidades de muestreo 23 (13%) resultaron positivas y 174 (87%) resultaron negativas. Se pudo observar una mayor frecuencia de granjas positivas con poblaciones de engorda mayor a 7000 cerdos de engorda. Conclusión. Se puede concluir que la bacteria Lawsonia intracellularis está presente en granjas porcinas del estado de Yucatán con prevalencias ≥ 25%.

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Riris, Ida Duma, Albinus Silalahi, Tita Juwitaningsih e Wesly Hutabarat. "Antimicrobial Activities of Some Indonesian Medicinal Plants against Propionibacterium acnes (ATCC 27853) and Staphylococcus epidermis (ATCC 12228) causing Acne". Asian Journal of Chemistry 32, n. 1 (18 novembre 2019): 41–44. http://dx.doi.org/10.14233/ajchem.2020.22225.

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Secondary metabolites investigation of local plants, such as Psidium guajava L, Curcuma longa rhizome, Citrus hystrix and Lawsonia intracellularis shown that they have antibacterial activities against Propionibacterium acnes (ATCC 27853) and Staphylococcus epidermis (ATCC 12228) with chloramphenicol as antibiotic controlled. The phytoscreening method used to find out compounds in the plants and inhibition tests carried out by diffuse test with a concentration variation of 10, 5, 2.5 and 1.25 %. It was found that Lawsonia intracellularis plants has the highest inhibitory growth of 17; 12, 15, 14, 12 mm at 10 % concentration.

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Chiriboga, Adriana E. C. Nascimento, Walter V. Guimarães, Maria Cristina D. Vanetti e Elza F. Araújo. "Detection ofLawsonia intracellularisin faeces of swine from the main producing regions in Brazil". Canadian Journal of Microbiology 45, n. 3 (1 marzo 1999): 230–34. http://dx.doi.org/10.1139/w98-234.

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Swine proliferative enteropathy is an enteric disease caused by Lawsonia intracellularis which affects animals between 6 and 20 weeks of age, causing diarrhea, anorexia, and poor growth. The presence of L. intracellularis was evaluated in the faecal samples of 636 swine from 75 randomly chosen herds in the main swine-producing regions of Brazil. The pathogen was detected by the polymerase chain reaction method (PCR) using L. intracellularis specific primers. A 319-bp DNA fragment specific for L. intracellularis was produced on amplification of DNA from the faeces of pigs with proliferative enteropathy. Equal amounts of DNA extracted from the faeces of animals from the same herd were pooled together and, once L. intracellularis was detected, the faecal material of each animal was analyzed separately. The incidence of L. intracellularis was 33.4% in the state of Santa Catarina, 29.4% in Paraná, 26.3% in Minas Gerais, 16.7% in Mato Grosso, and 7.1% in São Paulo. The presence of the pathogenic agent was detected in samples from 15 farms, representing a total incidence of 20%. Although 46 animals (7.2%) were shown to be infected, 11% did not present any symptoms of swine proliferative enteropathy. The use of PCR allowed the detection of L. intracellularis in swine farms and the evaluation of the incidence of proliferative enteropathy in different regions of Brazil.Key words: proliferative enteropathy, diagnosis, Lawsonia intracellularis, PCR, incidence.

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Viott, Aline de M., Silvia A. França, Fábio A. Vannucci, Eduardo C. C. Cruz Jr, Mirella C. Costa, Connie J. Gebhart e Roberto M. C. Guedes. "Infection of sparrows (Passer domesticus) and different mice strains with Lawsonia intracellularis". Pesquisa Veterinária Brasileira 33, n. 3 (marzo 2013): 372–78. http://dx.doi.org/10.1590/s0100-736x2013000300016.

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The susceptibility of sparrows (Passer domesticus) and strains of mice (Swiss, BALB/c, C-57 and DB-A) to Lawsonia intracellularis infection was studied. Thirty-two sparrows were inoculated with pure culture of L. intracellularis and eleven received sham inoculum. Feces were collected on -1, 7, 14 and 21 days post infection (dpi) for detection of L. intracellularis by PCR. After 21 days, all sparrows were euthanized and the tissues processed for histology and immunohistochemistry (IHC). One hundred sixty mice of four different strains (n=40, per strain) were used. For each mouse strain, 16 animals received mucosa homogenate from a pig infected with L. intracellularis, 16 received pure culture of L. intracellularis and eight animals received sham inoculum. Two control and four inoculated mice from each group were euthanized on 7, 14, 21 and 28 dpi. Sections of intestine were collected for histologic analysis and IHC and pooled feces were collected for L. intracellularis PCR. None of the sparrows had any histologic lesions characteristic of proliferative enteropathy or antigen labeling by IHC. All sparrow fecal samples were negative by PCR. All mice strains studied had histopathological lesions typical of PE and IHC labeling consistent with L. intracellularis infection, especially those animals inoculated with pure culture. The most severe lesions were observed in DB-A and Swiss mice. Fecal shedding was detected in all mice strains, with peak at 14 dpi. We conclude that sparrows do not seem to be relevant in the epidemiology of L. intracellularis. The results showed variations in the lesions among the four mice strains used.

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Helm, Emma T., Eric R. Burrough, Fernando L. Leite e Nicholas K. Gabler. "85 Vaccination Mitigates Performance Losses During a Lawsonia Intracellularis Experimental Challenge". Journal of Animal Science 99, Supplement_1 (1 maggio 2021): 8. http://dx.doi.org/10.1093/jas/skab054.012.

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Abstract Lawsonia intracellularis is endemic to swine herds worldwide. Currently, vaccination is one of the few strategies available to mitigate L. intracellularis. Thus, this study aimed to characterize the impact of vaccination on growth performance and disease severity during experimental challenge. Thirty-six L. intracellularis negative barrows were assigned to treatment groups as follows (n = 12/trt): 1) nonvaccinated, L. intracellularis negative (NC); 2) nonvaccinated, L intracellularis challenged (PC); and 3) L. intracellularis challenged, vaccinated (Enterisol® Ileitis, Boehringer Ingelheim) at 1 week postweaning (VAC). On days post inoculation (dpi) 0 (7 weeks post-weaned) PC and VAC pigs were inoculated with L. intracellularis. Individual feed disappearance and BW were recorded weekly and all pigs were euthanized at dpi 21. Post-inoculation, ADG was reduced in PC (P < 0.001) and VAC (P = 0.001) pigs compared with NC pigs. Average daily gain was additionally reduced in PC pigs compared with VAC pigs (P < 0.001). Similarly, ADFI was reduced in PC (P < 0.001) and VAC (P = 0.029) pigs compared with NC pigs, and further reduced in PC pigs compared with VAC pigs (P = 0.032). Overall G:F was reduced in PC pigs compared with NC (P < 0.001) and VAC (P = 0.015) pigs, which did not differ. For antibody response and fecal shedding, NC pigs remained negative. Antibody responses and fecal shedding were lower in VAC pigs compared with PC pigs (P < 0.05). Ileal gross lesion severity was greater in PC pigs compared with VAC (P = 0.018) and NC (P = 0.003) pigs, which did not differ. Similarly, ileal lesion length was greater in PC pigs compared with NC (P = 0.007) and VAC (P = 0.045) pigs. Microscopic lesion severity was greater in PC pigs compared with both PC and VAC pigs (P < 0.05). Taken together, these data characterize the impact L. intracellularis has on growth performance of pigs and highlight the importance of vaccination to prevent disease associated performance losses.

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Wuersch, K., D. Huessy, C. Koch e A. Oevermann. "Lawsonia intracellularis Proliferative Enteropathy in a Filly". Journal of Veterinary Medicine Series A 53, n. 1 (febbraio 2006): 17–21. http://dx.doi.org/10.1111/j.1439-0442.2006.00776.x.

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Fiskett, Rose Ann M. "Lawsonia intracellularis Infection in Hamsters (Mesocricetus auratus)". Journal of Exotic Pet Medicine 20, n. 4 (ottobre 2011): 277–83. http://dx.doi.org/10.1053/j.jepm.2011.07.003.

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Jensen, T. K. "Lawsonia intracellularis enteritis in two danish foalS". Journal of Comparative Pathology 152, n. 1 (gennaio 2015): 82. http://dx.doi.org/10.1016/j.jcpa.2014.10.167.

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Breuer, J., F. Schmoll, A. Spallek, S. Recknagel, A. Uhlig e G. F. Schusser. "Lawsonia intracellularis in foals – a serological analysis". Pferdeheilkunde Equine Medicine 26, n. 5 (2010): 697–700. http://dx.doi.org/10.21836/pem20100505.

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Feary, D. J., C. J. Gebhart e N. Pusterla. "Lawsonia intracellularis proliferative enteropathy in a foal". Schweizer Archiv für Tierheilkunde 149, n. 3 (1 marzo 2007): 129–33. http://dx.doi.org/10.1024/0036-7281.149.3.129.

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Gebhart, C. J., M. R. Kelley e Y. Chander. "Molecular typing of equine Lawsonia intracellularis isolates". Journal of Equine Veterinary Science 32, n. 10 (ottobre 2012): S32—S33. http://dx.doi.org/10.1016/j.jevs.2012.08.075.

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Park, Sungwoo, Perumalraja Kirthika, Vijayakumar Jawalagatti, Amal Senevirathne e John Hwa Lee. "Salmonella delivered Lawsonia intracellularis novel epitope-fusion vaccines enhance immunogenicity and confers protection against Lawsonia intracellularis in mice". Veterinary Microbiology 263 (dicembre 2021): 109264. http://dx.doi.org/10.1016/j.vetmic.2021.109264.

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Silva, Rodrigo Otávio Silveira, Michelle de Paula Gabardo, Juliana Saes Vilaça de Oliveira, Francisco Carlos Faria Lobato e Roberto Maurício Carvalho Guedes. "Detection of Lawsonia intracellularis fecal shedding in dogs in Minas Gerais, Brazil". Ciência Rural 45, n. 9 (30 giugno 2015): 1619–21. http://dx.doi.org/10.1590/0103-8478cr20141533.

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<p><bold>Lawsonia intracellularis</bold>is an obligate intracellular bacterium that is responsible for proliferative enteropathy, an enteric disease endemic in swine and common in foals. However, few studies have investigated this disease in dogs, and there are no reports of dogs infected with<bold> L. intracellularis</bold>in Latin America. The aim of this study was to evaluate the fecal shedding of<bold> L. intracellularis</bold>in diarrheic and non-diarrheic dogs in Minas Gerais, Brazil. A total of 58 dogs, 18 apparently healthy and 40 diarrheic, were examined in this study. DNA extracted from feces was analyzed using a nested PCR reaction to detect<bold> L. intracellularis.</bold>Three out of 40 (7.5%) diarrheic samples, all from 3-month-old puppies, were positive for<bold> L. intracellularis</bold>. These results highlight the need for additional studies to examine the role of this pathogen as a possible cause of enteric disease in dogs</p>

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Campillo, Marta, Sionagh H. Smith, David L. Gally e Tanja Opriessnig. "Review of methods for the detection of Lawsonia intracellularis infection in pigs". Journal of Veterinary Diagnostic Investigation 33, n. 4 (19 marzo 2021): 621–31. http://dx.doi.org/10.1177/10406387211003551.

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Lawsonia intracellularis is an obligate intracellular bacterium associated with enteric disease in pigs. Clinical signs include weight loss, diarrhea, and, in some cases, sudden death. The hallmark lesion is the thickening of the intestinal mucosa caused by increased epithelial cell replication, known as proliferative enteropathy. The immune response to L. intracellularis is not well defined, and detection of the infection, especially in the early stages, is still a significant challenge. We review here the main approaches used to identify this important but poorly understood pathogen. Detection of L. intracellularis infection as the cause of clinical disease is confounded by the high prevalence of the pathogen in many countries and that several other pathogens can produce similar clinical signs. A single L. intracellularis–specific ELISA and several amplification assays are available commercially to aid detection and surveillance, although histopathology remains the primary way to reach a conclusive diagnosis. There are major gaps in our understanding of L. intracellularis pathogenesis, especially how the host responds to infection and the factors that drive infection toward different clinical outcomes. Knowledge of pathogenesis will increase the predictive value of antemortem tests to guide appropriate interventions, including identification and treatment of subclinically affected pigs in the early stages of disease, given that this important manifestation reduces pig productivity and contributes to the economic burden of L. intracellularis worldwide.

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Cecco, Bianca Santana de, Regina Tose Kemper, Susy Hermes de Sousa, Ronaldo Viana Leite-Filho, Raquel Aparecida Sales da Cruz, Roberto Mauricio Carvalho Guedes, David Driemeier e Luciana Sonne. "Proliferative enteropathy caused by Lawsonia intracellularis in rabbits in Southern Brazil". Semina: Ciências Agrárias 41, n. 5supl1 (7 agosto 2020): 2429–36. http://dx.doi.org/10.5433/1679-0359.2020v41n5supl1p2429.

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Proliferative enteropathy (PE), also known as ileitis, is a disease caused by the bacterium Lawsonia intracellularis. This disease is characterized by diarrhea and ill-thrift. The aim of this study is to describe a PE outbreak in rabbits that occurred in Southern Brazil. The farm had 700 rabbits at the time the outbreak occurred. The clinical signs were severe diarrhea, dehydration, and apathy. Necropsy was performed in 33 rabbits, and the most evident macroscopic findings were thickening of the intestinal wall, intestinal loops distended by large amounts of gas, and liquid feces. Histopathological examination demonstrated a marked proliferation of enterocytes in intestinal crypts, decrease number of goblet cells, and crypts microabscesses. Silver impregnation technique (Warthin-Starry) demonstrated in intestinal crypts inside of enterocytes cytoplasm, curved vibrioid bacteria compatible with L. intracellularis. Immunohistochemical staining with anti-L. intracellularis confirmed the agent presence. PCR was performed and L. intracellularis was confirmed as the etiological agent.

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Klaeui, Caitlin, Ramya Lekha Medida, Matthew Stone, Lacey Marshall-lund, Connie Gebhart e Milena Saqui-Salces. "PSV-13 Lawsonia Intracellularis Increases Cell Proliferation in Swine Enteroids in Vitro". Journal of Animal Science 100, Supplement_2 (12 aprile 2022): 191–92. http://dx.doi.org/10.1093/jas/skac064.323.

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Abstract Lawsonia intracellularis is an enteric pathogen that causes thickening of the intestinal mucosa layer resulting in malnutrition, diarrhea, and poor weight gain in swine. L. intracellularis increases intestinal cell proliferation in vivo. Swine enteroids are 3-dimensional in vitro models that can be used to study bacterial infections. The objective of this study was to evaluate cellular proliferation in swine enteroids infected by L. intracellularis. Ki-67 is a protein expressed by cells that are actively proliferating and is often used to document changes in proliferation. Swine enteroids were cultured in monolayers using transwells, infected with L. intracellularis (PHE/MN1-00), and harvested on 5, 7, and 14 d post infection (dpi). Enteroid monolayers were fixed in 4% formaldehyde overnight, and immunofluorescence for Ki-67 and L. intracellularis were performed. Experiments were replicated 3 times. Immunofluorescent staining using L. intracellularis antibodies demonstrated infection of enteroids. Cell proliferation was assessed by counting the number of Ki-67 positive cells under 20x magnification and comparing to the total number of cells as stained by 4′,6-diamidino-2-phenylindole (DAPI) in infected and non-infected enteroids. Cell counts were analyzed using paired t-test in GraphPad Prism comparing infected enteroids with uninfected enteroids for each dpi time. Cell proliferation between non-infected and infected enteroids were not different at 5 dpi (0.014±0.007 vs. 0.044±0.021, P = 0.21) or 14 dpi (0.101±0.10 vs. 0.061±0.034, P = 0.46). However, at 7 dpi, infected enteroids showed greater cell proliferation (0.67±0.056 vs. 0.078±0.58, P = .047). In infected pigs, it was reported that increased cell proliferation is observed at 7 dpi. In vitro swine enteroids reproduce the proliferative changes observed in vivo, validating their use as a model for L. intracellularis infection.

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25

Duhamel, G. E., E. C. Klein, R. O. Elder e C. J. Gebhart. "Subclinical Proliferative Enteropathy in Sentinel Rabbits Associated with Lawsonia intracellularis". Veterinary Pathology 35, n. 4 (luglio 1998): 300–303. http://dx.doi.org/10.1177/030098589803500410.

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Light microscopic and ultrastructural changes of naturally acquired proliferative enteropathy were observed in two of three young sentinel New Zealand White rabbits. The etiologic agent, Lawsonia intracellularis, was demonstrated in the tissues using morphologic, immunohistochemical, and molecular methods. Proliferative enteropathy was associated with infection of villous and crypt enterocytes by intracellular organisms genotypically and antigenically related to L. intracellularis of various other animal species.

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26

Schulze Johann, R., J. Verspohl e M. Wendt. "Epidemiologische Untersuchungen zum Vorkommen von Lawsonia-intracellularis-Infektionen in Schweinebeständen". Tierärztliche Praxis Ausgabe G: Großtiere / Nutztiere 34, n. 04 (2006): 230–39. http://dx.doi.org/10.1055/s-0037-1621074.

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Zusammenfassung: Gegenstand und Ziel: Anhand serologischer Screening-Untersuchungen in Schweinebeständen wird eine Übersicht zur Prävalenz von Lawsonia-(L.-)intracellularis-Infektionen in Deutschland gegeben. In acht Betrieben mit geschlossenem System wurde zudem in einer Querschnittsstudie der zeitliche Ablauf der Serokonversion überprüft. Der Nachweis von Lawsonien in Kot- und Darmproben aus Betrieben mit Durchfallproblematik sollte mit dem Vorkommen von Brachyspiren, Salmonellen und Escherichia (E.) coli verglichen werden. Material und Methoden: Die serologische Untersuchung von Blutproben (Herdenscreening: n = 7546 aus 694 Betrieben, Querschnittsstudie: n = 936 aus acht Betrieben) auf Antikörper gegen L. intracellularissowie der Nachweis von L. intracellularisaus Kot- und Darmproben (n = 826 aus 403 Betrieben) erfolgte mittels indirektem Immunfluoreszenztest. Der Nachweis von Brachyspiren, Salmonellen und E. coli wurde mithilfe kultureller Verfahren durchgeführt. Ergebnisse: Serologisch positive Reagenten ergaben sich bei 43,2% der Blutproben und bei 81,3% der untersuchten Bestände. Sauen haltende Bestände und reine Mastbetriebe waren häufiger seropositiv als Ferkelaufzuchtbetriebe mit und ohne Mast. Antikörper gegen L. intracellularis fanden sich ähnlich häufig in Herden mit klinischer Symptomatik einer porzinen proliferativen Enteropathie (PPE) wie in Herden ohne oder mit anderen klinischen Erkrankungen. Die Querschnittsuntersuchung ergab, dass erste Reagenten schon zur 10. Lebenswoche auftreten, der Hauptanteil jedoch zwischen der 13. und 16. Lebenswoche. Die bakteriologischen Untersuchungen belegen, dass in Beständen mit Durchfallproblematik hämolysierende E. coli(48,4%) und L. intracellularis (33,7%) wesentlich häufiger nachweisbar sind als B. hyodysenteriae (21,1%), Salmonellen (17,3%) oder B. pilosicoli (2,5%). Mischinfektionen von B. hyodysenteriae (3,5%), B. pilosicoli (1,0%) oder Salmonellen (5,6%) zusammen mit L. intracellularis waren selten. Schlussfolgerung und klinische Relevanz: Die sehr weite Verbreitung von L. intracellularis in Deutschland in klinisch unauffälligen Herden wie auch in Beständen mit Durchfall- und Kümmererproblematik erfordert eine gezielte Diagnostik zum Ausschluss anderer Durchfallerreger.

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27

Leite, Fernando L., Juan E. Abrahante, Erika Vasquez, Fabio Vannucci, Connie J. Gebhart, Nathan Winkelman, Adam Mueller, Jerry Torrison, Zachary Rambo e Richard E. Isaacson. "A Cell Proliferation and Inflammatory Signature Is Induced by Lawsonia intracellularis Infection in Swine". mBio 10, n. 1 (29 gennaio 2019): e01605-18. http://dx.doi.org/10.1128/mbio.01605-18.

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ABSTRACT Lawsonia intracellularis causes porcine proliferative enteropathy. This is an enteric disease characterized by thickening of the wall of the ileum that leads to decreased growth of animals and diarrhea. In this study, we investigated the host response to L. intracellularis infection by performing transcriptomic and pathway analysis of intestinal tissue samples from groups of infected and noninfected animals at 14, 21, and 28 days postchallenge. At the peak of infection, when animals developed the most severe lesions, infected animals had higher levels of several gene transcripts involved in cellular proliferation and inflammation, including matrix metalloproteinase-7 (MMP7), transglutaminase-2 (TGM2), and oncostatin M (OSM). Histomorphology also revealed general features of intestinal inflammation. This study identified important pathways associated with the host response in developing and resolving lesions due to L. intracellularis infection. IMPORTANCE Lawsonia intracellularis is among the most important enteric pathogens of swine, and it can also infect other mammalian species. Much is still unknown regarding its pathogenesis and the host response, especially at the site of infection. In this study, we uncovered several novel genes and pathways associated with infection. Differentially expressed transcripts, in addition to histological changes in infected tissue, revealed striking similarities between L. intracellularis infection and cellular proliferation mechanisms described in some cancers and inflammatory diseases of the gastrointestinal tract. This research sheds important light into the pathogenesis of L. intracellularis and the host response associated with the lesions caused by infection.

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28

Medida, Ramya Lekha, Talita P. Resende, Connie Gebhart e Milena Saqui-Salces. "24 Validation of swine enteroids as a model to study Lawsonia intracellularis pathogenesis". Journal of Animal Science 97, Supplement_3 (dicembre 2019): 21–22. http://dx.doi.org/10.1093/jas/skz258.041.

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Abstract Lawsonia intracellularis is an obligate intracellular bacterium that causes proliferative ileitis, an enteric disease that costs more than $100 million annually to the US swine industry. Information about L. intracellualris pathogenesis is scarce due to lack of suitable in vitro models to study the infection-induced proliferative changes. L. intracellularis infection of the swine ileum has been shown to decrease the number of mucin-producing goblet cells and increase cell proliferation along with amplification of transient amplifying cells demonstrated by the expression of SOX9. The objective of this study was to validate the use of swine enteroids (three dimensional structures derived from adult intestinal stem cells) as a model to study the intestinal epithelial changes caused by L. intracellularis infection. Swine enteroids plated on transwell plate inserts to cover the surface area were infected with 108 L. intracellularis organisms in culture media per well and incubated at 37⁰C with atmospheric conditions of 8.0% oxygen, 8.8% carbon dioxide, and 83.2% nitrogen. Infected enteroids were collected after 7 days and gene expression levels of mucin 2 (MUC2), enterocyte marker fatty acid binding protein (FABP), endocrine marker chromogranin A (CGA), intestinal epithelium marker villin 1 (VIL1), paneth cell marker lysozyme (LYZ), proliferating cell nuclear antigen (PCNA) and SOX9 were measured. The expression of FABP and LYZ in L. intracellularis infected swine enteroids decreased by 50% and 20% respectively and the expression of SOX9 increased by 50%, with no significant changes for the levels of VIL1 and CGA. The changes observed in the infected swine enteroids reflect the profile of gene expression observed in L. intracellularis infected ileal tissue. Therefore, swine enteroids are a suitable in vitro system to study the dynamics of cell differentiation and proliferation of the intestinal epithelium induced by L. intracellularis infection.

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29

Untersperger, M., H. Schweighardt, M. Schuh, M. Awad-Masalmeh e M. Dünser. "Diagnostik der porzinen proliferativen Enteropathien: Vergleich unterschiedlicher Nachweismethoden zur Erfassung von Lawsonia intracellularis". Tierärztliche Praxis Ausgabe G: Großtiere / Nutztiere 31, n. 02 (2003): 99–105. http://dx.doi.org/10.1055/s-0038-1623014.

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ZusammenfassungUnterschiedliche Nachweisverfahren zur Erfassung der Lawsonia-intracellularis-Infektionen des Schweines wurden miteinander verglichen. Zum direkten Erregernachweis dienten eine modifizierte Ziehl-Neelsen-Färbung, die In-situ-Hybridisierung sowie die PCR. Der serologische Nachweis L.-intracellularis-spezifischer Antikörper erfolgte mittels indirekter Immunfluoreszenz (IFAT). Bei 65 Schweinen mit Durchfallproblematik erzielte im direkten Erregernachweis die PCR mit 31% positiver Proben die höchste Sensitivität, gefolgt von der In-situ-Hybridisierung (23% positive Proben) und der modifizierten Ziehl-Neelsen-Färbung (17% positive Proben). Bei 46% der Tiere konnten überdies Antikörper gegen L. intracellularis nachgewiesen werden.Bei 580 Tieren aus 47 L.-intracellularis-positiven Betrieben wurden vergleichend Kotproben mittels PCR und Serumproben mittels IFAT untersucht. Bei 18,6% der Schweine konnten eine Erregerausscheidung und bei 51,4% der Tiere Antikörper nachgewiesen werden.Der IFAT kann als Verfahren zum Herdenscreening eingesetzt werden, zur weiteren Abklärung bzw. Interpretation der Ergebnisse ist ein direkter Erregernachweis anzuschließen.

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30

Kroll, J. J., M. A. Eichmeyer, M. L. Schaeffer, S. McOrist, D. L. Harris e M. B. Roof. "Lipopolysaccharide-Based Enzyme-Linked Immunosorbent Assay for Experimental Use in Detection of Antibodies to Lawsonia intracellularis in Pigs". Clinical Diagnostic Laboratory Immunology 12, n. 6 (giugno 2005): 693–99. http://dx.doi.org/10.1128/cdli.12.6.693-699.2005.

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ABSTRACT An enzyme-linked immunosorbent assay (ELISA) for Lawsonia intracellularis was developed and compared with a whole-cell antigen-based immunofluorescence antibody test (IFAT). The antigen-containing lipopolysaccharide (LPS) was derived from Percoll gradient purified cultures of L. intracellularis by using a modification of the Westphal hot phenol procedure. The antigen was bound directly to polystyrene 96-well microtiter plates, and the assay was performed in an indirect ELISA format. Specificity and sensitivity values based on 80 known positive and 80 known negative serum samples from controlled experimental trials were 93.7% and 88.7%, respectively. Serological results from a controlled L. intracellularis challenge exposure study confirmed the high specificity and sensitivity of this assay (100% and 99.5%, respectively). Comparisons between the LPS ELISA and the IFAT in detecting anti-Lawsonia antibodies in this controlled study revealed significantly more LPS ELISA-positive pigs than IFAT-positive pigs on days 21, 28, 35, and 42 (P = 0.003, 0.030, 0.002, and 0.006, respectively). This indirect ELISA (LPS ELISA) test is an improved method of detecting antibodies in pigs soon after exposure to L. intracellularis, regardless of isolate type (vaccine or wild type) in experimental studies. The LPS ELISA may be used as a tool to support future research trials on vaccine efficacy and to further understand the immune response induced by L. intracellularis.

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31

Drolet, Richard, Danielle Larochelle e Connie J. Gebhart. "Proliferative Enteritis Associated with Lawsonia Intracellularis (Ileal Symbiont Intracellularis) in White-Tailed Deer". Journal of Veterinary Diagnostic Investigation 8, n. 2 (aprile 1996): 250–53. http://dx.doi.org/10.1177/104063879600800219.

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32

SAMPIERI, F., K. W. HINCHCLIFF e R. E. TORIBIO. "Tetracycline therapy of Lawsonia intracellularis enteropathy in foals". Equine Veterinary Journal 38, n. 1 (5 gennaio 2010): 89–92. http://dx.doi.org/10.2746/042516406775374270.

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33

Jensen, T. K., K. Moller, G. Christensen, T. D. Leser e S. E. Jorsal. "Monitoring ileitis and Lawsonia intracellularis in abattoir pigs". Veterinary Record 145, n. 21 (20 novembre 1999): 613–15. http://dx.doi.org/10.1136/vr.145.21.613.

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34

FRANK, N., C. E. FISHMAN, C. J. GEBHART e M. LEVY. "Lawsonia intracellularis proliferative enteropathy in a weanling foal". Equine Veterinary Journal 30, n. 6 (novembre 1998): 549–52. http://dx.doi.org/10.1111/j.2042-3306.1998.tb04533.x.

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35

Vannucci, F. A., S. Wattanaphansak e C. J. Gebhart. "An Alternative Method for Cultivation of Lawsonia intracellularis". Journal of Clinical Microbiology 50, n. 3 (4 gennaio 2012): 1070–72. http://dx.doi.org/10.1128/jcm.05976-11.

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36

Pusterla, Nicola, e Connie Gebhart. "Lawsonia intracellularis infection and proliferative enteropathy in foals". Veterinary Microbiology 167, n. 1-2 (novembre 2013): 34–41. http://dx.doi.org/10.1016/j.vetmic.2013.06.017.

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37

Jacobson, M., A. Aspan, A. Nordengrahn, M. Lindberg e P. Wallgren. "Monitoring of Lawsonia intracellularis in breeding herd gilts". Veterinary Microbiology 142, n. 3-4 (maggio 2010): 317–22. http://dx.doi.org/10.1016/j.vetmic.2009.09.034.

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38

Vannucci, Fabio A., Nicola Pusterla, Samantha M. Mapes e Connie Gebhart. "Evidence of host adaptation in Lawsonia intracellularis infections". Veterinary Research 43, n. 1 (2012): 53. http://dx.doi.org/10.1186/1297-9716-43-53.

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39

Ohta, T., K. Kimura, K. Katsuda, H. Kobayashi, O. Mikami, M. Haritani e T. Onodera. "Proliferative Enteropathy caused by Lawsonia intracellularis in Chickens". Journal of Comparative Pathology 156, n. 2-3 (febbraio 2017): 158–61. http://dx.doi.org/10.1016/j.jcpa.2016.11.274.

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40

Vannucci, F. A., N. Pusterla, S. M. Mapes, M. Kelley e C. J. Gebhart. "Evidence of host adaptation in Lawsonia intracellularis infections". Journal of Equine Veterinary Science 32, n. 10 (ottobre 2012): S44. http://dx.doi.org/10.1016/j.jevs.2012.08.097.

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41

Pedersen, Ken Steen, Klaus H. Pedersen, Charlotte Hjulsager, Lars Erik Larsen, Marie Ståhl, Helle Stege, Øystein Angen e Jens Peter Nielsen. "Within-day repeatability for absolute quantification of Lawsonia intracellularis bacteria in feces from growing pigs". Journal of Veterinary Diagnostic Investigation 24, n. 5 (11 luglio 2012): 968–70. http://dx.doi.org/10.1177/1040638712452111.

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Abstract (sommario):

Absolute quantification of Lawsonia intracellularis by real-time polymerase chain reaction (PCR) is now possible on a routine basis. Poor repeatability of quantification can result in disease status misclassification of individual pigs when a single fecal sample is obtained. The objective of the current study was to investigate overall variation within a day for fecal numbers of L. intracellularis bacteria determined by real-time PCR in growing pigs. From each of 30 pigs with an infection of L. intracellularis, 5 fecal samples were collected within 1 day. A total of 150 fecal samples were obtained and subjected to quantitative PCR (qPCR) testing. Mean fecal dry matter content was 14.3% (standard deviation = 4.5%). Two pigs (6.7%) alternated between being L. intracellularis qPCR positive and negative. For 28 pigs, the excreting levels of L. intracellularis were within the dynamic range of the qPCR assay at all sampling points. For these 28 pigs, the mean excretion level of L. intracellularis was 6.1 log10 bacteria/g feces (standard deviation = 1.2 log10 bacteria/g feces). The maximum observed difference between 2 fecal samples from the same pig was 1.1 log10 bacteria/g feces. The average standard deviation for individual pigs was 0.27 log10 bacteria/g feces. The average coefficient of variation within pigs was 0.04, ranging from 0.006 to 0.08. The results imply that absolute quantification of L. intracellularis by qPCR has acceptable repeatability within 1 day. However, a population-specific proportion of pigs alternating between positive and negative test results must be expected.

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42

Szczotka-Bochniarz, Anna, Katarzyna Podgórska, Agnieszka Nowak e Zygmunt Pejsak. "In vitro cultivation and immunostaining of Lawsonia intracellularis strains". Bulletin of the Veterinary Institute in Pulawy 57, n. 3 (1 settembre 2013): 319–22. http://dx.doi.org/10.2478/bvip-2013-0055.

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Abstract The aim of the study was to implement in vitro cultivation of L. intracellularis strains using ATCC 55783 and vaccine strains, and McCoy cells (ATCC CRL-1696). The infection was monitored by daily observations under phase contrast microscope. Indirect immunostaining using monoclonal antibody was also performed. Large number of S-shaped, moving bacteria were found in the cell medium in cultures infected with ATCC 55783 and vaccine strain. Immunostaining revealed a high number of multiple cell-associated or intracellular red stained bacteria in the infected cultures. This study describes for the first time in vitro cultivation of L. intracellularis in Poland, which creates further perspective for more advanced research on this bacterium.

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43

Hagen, B., e G. Bilkei. "Seroprevalence of Lawsonia intracellularis in large pig production units". Acta Veterinaria Hungarica 51, n. 2 (1 marzo 2003): 165–70. http://dx.doi.org/10.1556/avet.51.2003.2.4.

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In 11 'farrow-to-finish' outdoor or indoor production units, blood samples from late pregnant gilts were tested by indirect immunofluorescence antibody (IFA) serum assay for Lawsonia intracellularis. The offspring of positively tested gilts were tested at 2, 7, 12, 17, 22 and 27 weeks of age for seroprevalence of Lawsonia intracellularis. All offspring of IFA positive gilts were seronegative at 2 and 7 weeks of age. At 12 weeks of age 81.0% of indoor and 51.0% of outdoor pigs were tested positive. While at 17 weeks of age 82.5% of indoor-raised pigs showed seropositivity, in outdoor units the seropositivity declined to 31.3%. At weeks 22 and 27 indoor-raised pigs still showed marked seropositivity (17.7% and 11.5%) but their outdoor-raised counterparts revealed declining values (7.4% and 0%).

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44

Byung-Yong, PARK, SHIM Kwan-Seob, KIM Won-Il, HOSSAIN Md Mukter, KIM Bumseok, KWON Jungkee, PARK Choi-Kyu, CHO Sung-Jin, JO Inho e CHO Ho-Seong. "Rapid And Sensitive Detection Of Lawsonia Intracellularis In Pigs By Real-Time Loop-Mediated Isothermal Amplification". Acta Veterinaria 65, n. 1 (1 marzo 2015): 20–29. http://dx.doi.org/10.1515/acve-2015-0002.

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Abstract (sommario):

Abstract A simple and rapid real-time loop-mediated isothermal amplification (LAMP) assay designed to detect Lawsonia (L.) intracellularis, an important bacteria causing proliferative enteropathy in pigs. A set of four primers targeting the ubiquinone/menaquinone biosynthesis methylase (ubiE) gene was designed for the LAMP reaction. Additionally, serial 10-fold dilutions of cultured L. intracellularis and spiked feces were also used for the optimization of real-time LAMP. The lower limit of the linear range of the assay in L. intracellularis was 1.0 × 100 L. intracellularis. Real-time LAMP was 10 and 100 times more sensitive than real-time PCR and conventional PCR detection methods, respectively. Based on testing of 213 porcine fecal samples using real-time LAMP, realtime PCR and PCR, the agreement quotients of real-time LAMP with conventional PCR and with real-time PCR were 0.77 and 0.95, respectively. This study demonstrated that real-time LAMP was a powerful tool for the rapid and sensitive detection of L. intracellularis in porcine fecal samples.

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45

Smith, David G. E., Suzanne C. Mitchell, Tony Nash e Susan Rhind. "Gamma Interferon Influences Intestinal Epithelial Hyperplasia Caused by Lawsonia intracellularis Infection in Mice". Infection and Immunity 68, n. 12 (1 dicembre 2000): 6737–43. http://dx.doi.org/10.1128/iai.68.12.6737-6743.2000.

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Abstract (sommario):

ABSTRACT Lawsonia intracellularis is a recently identified bacterial pathogen which causes disease in a broad range of animals. Invasion of intestinal epithelial cells and the resultant hyperplasia of infected cells are central processes in disease pathogenesis. In this study, we aimed to establish whether immunocompetent mice were susceptible to infection and whether gamma interferon (IFN-γ) contributed to the pathogenesis of infection. Wild-type 129-Sv-Ev mice (129 mice) and IFN-γ receptor knockout mice based on the 129 background (IFN-γR−) were challenged orally with approximately 5.5 × 107 L. intracellularis cells. Both 129 and IFN-γR− mice became infected, although the extent of infection (as determined by the proportion of infected crypts) was substantially lower in 129 mice than in IFN-γR− mice. Despite these differences, infected crypts showed characteristics typical of proliferative enteropathies of other animals, i.e., intracellular colonization of epithelial cells byL. intracellularis with resultant epithelial hyperplasia. Infection in 129 mice was cleared between days 21 and 28 postchallenge, whereas infection in IFN-γR− mice was evident in 100% of animals from day 21 onward. Additionally, in IFN-γR−mice the infection was so extensive that fatalities resulted. IFN-γ therefore plays a significant role in limiting intracellular infection and increased cellular proliferation associated with L. intracellularis. L. intracellularis infection is generally associated with modest cellular infiltration; therefore, further comparative examinations will be necessary to determine pathogenicity factors and define the role of IFN-γ in controlling this infection.

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46

HUSNÍK, R., J. KLIMEŠ, K. TOMANOVÁ, J. SMOLA, R. HALOUZKA, F. TICHÝ e J. BRÁZDIL. "Lawsonia intracellularis in a dog with inflammatory bowel disease". Veterinární Medicína 48, No. 5 (30 marzo 2012): 141–45. http://dx.doi.org/10.17221/5761-vetmed.

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A two-year-old male German short-haired pointer was presented with a 1.5-year history of intermittent small-bowel diarrhoea. Inflammatory bowel disease (chronic lymphocytic-plasmacytic gastritis, enteritis and colitis) was diagnosed on the basis of histological examination of biopsies obtained on repeated endoscopy and by exclusion of other possible causes. Warthin-Starry silver staining of stomach mucosa revealed the presence of gastric spiral organisms. The evidence of L. intracellularis was provided by a positive nested polymerase chain reaction in one biopsy of duodenal mucosa and in one rectal smear. In 5 blood sera collected over a period of 8 months the IgG antibodies to L. intracellularis were found by an indirect fluorescent antibody test. Treatment with oral prednisone led only to a temporary improvement.

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47

Boye, M., T. K. Jensen, K. Møller, T. D. Leser e S. E. Jorsal. "Specific Detection of Lawsonia intracellularis in Porcine Proliferative Enteropathy Inferred from Fluorescent rRNA In Situ Hybridization". Veterinary Pathology 35, n. 2 (marzo 1998): 153–56. http://dx.doi.org/10.1177/030098589803500212.

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Abstract (sommario):

Fluorescent in situ hybridization targeting 16S ribosomal RNA was used for specific detection of the obligate intracellular bacterium Lawsonia intracellularis in enterocytes from pigs affected by proliferative enteropathy. A specific oligonucleotide probe was designed and the specificity of the probe was determined by simultaneous comparison with indirect immunofluorescence assay for detection of L. intracellularis in formalin-fixed tissue samples from 15 pigs affected by porcine proliferative enteropathy. We used 10 tissue samples from pigs without proliferative mucosal changes as negative controls. The results showed that the oligonucleotide probe is specific for L. intracellularis and that fluorescent in situ hybridization targeting ribosomal RNA is a suitable and fast method for specific detection and histological recognition of L. intracellularis in formalin-fixed tissue.

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48

Smith, Geoffrey, Duncan Brown e Alan Rowland. "Gordon Hugh Kerr Lawson". Veterinary Record 182, n. 7 (15 febbraio 2018): 204. http://dx.doi.org/10.1136/vr.k748.

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A brilliant research academic who identified a new genus of bacteria, Lawsonia intracellularis. He was also a man of integrity and kindness, always willing to don his white coat to help any technician or student.

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49

Zlotowski, Priscila, André Mendes Ribeiro Corrêa, Mauro Riegert Borba, Cláudio Estêvão Farias Cruz e David Driemeier. "Enteritis associated with Lawsonia intracellularis and porcine circovirus type 2 infection in wild boars in Southern Brazil". Ciência Rural 38, n. 9 (8 aprile 2008): 2540–44. http://dx.doi.org/10.1590/s0103-84782008005000003.

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In a commercial herd of 1250 wild boars, 56 animals were affected by anorexia, diarrhea, and wasting. Enlargement of mesenteric lymph nodes, thickening of ileal wall, and a white-yellowish ileal content were observed in two of the four animals necropsied. Microscopically, ileal crypts showed epithelial hyperplasia, moderate decrease in goblet cell density, lymphohistiocytic infiltrate in the lamina propria, and moderate depletion with histiocytic infiltrate in Peyer's patches. Curved rod-shaped organisms within the apical cytoplasm of enterocytes were observed in both Warthin-Starry and Lawsonia intracellularis-immunostained sections. PCV2 antigen was observed in ileal Peyer's patches of 3 wild pigs. Trichuris suis nematodes were found in the cecum of the four wild pigs. This report describes clinicopathological findings in cases of enteritis associated with Lawsonia intracellularis and PCV2 infection in a commercial herd of wild boars.

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50

Peixoto, Paulo V., Ticiana N. França, Carlos T. Ribeiro, Pedro S. Bezerra Jr e David Driemeier. "Proliferative enteropathy (Lawsonia intracellularis) outbreak in rabbits in Brazil". Pesquisa Veterinária Brasileira 28, n. 10 (ottobre 2008): 447–51. http://dx.doi.org/10.1590/s0100-736x2008001000001.

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Abstract (sommario):

An outbreak of Lawsonia intracellularis infection in rabbits, which occurred in 1988 in Rio de Janeiro state, Brazil, is reported. The disease had an acute course (24-48 hours) with clinical signs characterized by brownish or green diarrhea and dehydration. Occasionally, the animals died one day after the onset of diarrhea, without showing any other clinical signs. At necropsy, the ileum was prominent, firm and had a thickened wall; it was dilated in the caudal direction and had a somewhat reticulated appearance, perceptible through the serosa. The thickened mucous membrane had finely corrugated aspect and a shiny surface. The ileocecal valve and surrounding areas were slightly edematous and irregular. The Peyer's patches were sometimes more evident. There was moderate enlargement of the mesenteric lymph nodes. The histological examination revealed different degrees of hyperplasia of the epithelial cells of intestinal crypts consisting of poorly differentiated, hyperchromatic cells with high mitotic index, arranged in a pseudostratified layer which, in some cases, reached the apical portions of the villi. The inflammatory infiltrate between the hyperplastic epithelial cells was composed of lymphocytes, plasma cells, macrophages, some eosinophils and globular leukocytes. Silver impregnation revealed large numbers of bacteria with morphology of the genus Lawsonia in the apical pole of cryptal enterocytes. These bacteria reacted positively to a Lawsonia intracellularis polyclonal antibody by the avidin-biotin immunohistochemistry method.

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