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Artículos de revistas sobre el tema "Sporozoïde"

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Publicado: 4 de junio de 2021

Última modificación: 6 de febrero de 2022

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1

McKeever, Declan J. "Le progrès vers un vaccin contre Theileria parva : Pertinence pour la recherche sur la cowdriose". Revue d’élevage et de médecine vétérinaire des pays tropicaux 46, n.º 1-2 (1 de enero de 1993): 231–35. http://dx.doi.org/10.19182/remvt.9370.

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Beaucoup de progrès ont été enregistrés durant les 10 dernières années en ce qui concerne la caractérisation de l'immunité bovine contre Theileria parva. Il n'est plus à démontrer que les bovins devenus immunisés après infection peuvent se débarrasser d'infections ultérieures par le déploiement de lymphocytes T cytotoxiques (LTC) spécifiques pour le parasite. De plus, des anticorps neutralisants sont produits à des titres élevés contre la surface du sporozoïte après des infections multiples par le parasite, et peuvent neutraliser l'infection in vitro. Bien que cela ne soit vraisemblablement pas significatif dans les circonstances naturelles, on a tiré profit de cette dernière observation pour créer un candidat prometteur pour un vaccin neutralisant basé sur une forme recombinante de l'antigène de surface majeur des sporozoïtes de T. parva. On essaie actuellement d'identifier le(s) antigène(s) cible(s) des LTC spécifiques pour T. parva et, après réussite, un vaccin amélioré visant aussi bien les stades infectieux que pathogènes sera à portée. L'élucidation de la base de l'immunité des ruminants contre Cowdria ruminantium est encore à un stade relativement peu avancé. Néanmoins, on applique déjà à la cowdriose des techniques ayant mené à la compréhension de l'immunologie de T. parva.

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2

Hollingdale, Michael R., Robert E. Sinden y Jos van Pelt. "Sporozoite invasion". Nature 362, n.º 6415 (marzo de 1993): 26. http://dx.doi.org/10.1038/362026a0.

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3

Weitzman, Jonathan B. "Sporozoite transcriptome". Genome Biology 2 (2001): spotlight—20010809–01. http://dx.doi.org/10.1186/gb-spotlight-20010809-01.

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4

Morrison, Carol M. "Further observations on the sporogony of Eimeria sardinae in the testis of the herring Clupea harengus L." Canadian Journal of Zoology 69, n.º 4 (1 de abril de 1991): 1017–24. http://dx.doi.org/10.1139/z91-147.

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Sporocyst formation commences with division of the sporoblast nucleus, after which two sporozoites develop, one at each end of the sporoblast. A thickening beneath the limiting unit membrane of the sporoblast is the first indication of the sporozoite pellicle forming. This subsequently develops into a cone-shaped structure, which becomes the anterior end of the sporozoite as it separates from the sporocyst residuum. The sporozoites elongate as they mature, and the sporocyst residuum, containing amylopectin and refractile granules, becomes smaller. A typical apical complex is present at the blunt anterior end of the sporozoite. A homogeneous area containing paracrystals is present in both the sporoblast and the sporozoite. There are no refractile granules in the sporozoite. The sporocyst wall is thin and contains no mechanism for releasing the sporozoite, such as a Stieda body or suture.

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5

Joe, Angela, Renaud Verdon, Saul Tzipori, Gerald T. Keusch y Honorine D. Ward. "Attachment of Cryptosporidium parvumSporozoites to Human Intestinal Epithelial Cells". Infection and Immunity 66, n.º 7 (1 de julio de 1998): 3429–32. http://dx.doi.org/10.1128/iai.66.7.3429-3432.1998.

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ABSTRACT An enzyme-linked immunosorbent assay-based attachment model using the human intestinal cell line Caco-2A was developed to study attachment of Cryptosporidium parvum sporozoites in vitro and to assess potential inhibitors of sporozoite binding. In this system, attachment was related to sporozoite dose, incubation time, and host cell differentiation status. Polyclonal antibodies to C. parvum as well as glycoprotein inhibitors of a sporozoite lectin reduced attachment. This model will be a valuable tool in elucidating specific molecules and mechanisms involved in sporozoite-host cell attachment.

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6

Meerstein-Kessel, Lisette, Jeron Venhuizen, Daniel Garza, Nicholas I. Proellochs, Emma J. Vos, Joshua M. Obiero, Philip L. Felgner et al. "Novel insights from the Plasmodium falciparum sporozoite-specific proteome by probabilistic integration of 26 studies". PLOS Computational Biology 17, n.º 4 (30 de abril de 2021): e1008067. http://dx.doi.org/10.1371/journal.pcbi.1008067.

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Plasmodium species, the causative agent of malaria, have a complex life cycle involving two hosts. The sporozoite life stage is characterized by an extended phase in the mosquito salivary glands followed by free movement and rapid invasion of hepatocytes in the human host. This transmission stage has been the subject of many transcriptomics and proteomics studies and is also targeted by the most advanced malaria vaccine. We applied Bayesian data integration to determine which proteins are not only present in sporozoites but are also specific to that stage. Transcriptomic and proteomic Plasmodium data sets from 26 studies were weighted for how representative they are for sporozoites, based on a carefully assembled gold standard for Plasmodium falciparum (Pf) proteins known to be present or absent during the sporozoite life stage. Of 5418 Pf genes for which expression data were available at the RNA level or at the protein level, 975 were identified as enriched in sporozoites and 90 specific to them. We show that Pf sporozoites are enriched for proteins involved in type II fatty acid synthesis in the apicoplast and GPI anchor synthesis, but otherwise appear metabolically relatively inactive in the salivary glands of mosquitos. Newly annotated hypothetical sporozoite-specific and sporozoite-enriched proteins highlight sporozoite-specific functions. They include PF3D7_0104100 that we identified to be homologous to the prominin family, which in human has been related to a quiescent state of cancer cells. We document high levels of genetic variability for sporozoite proteins, specifically for sporozoite-specific proteins that elicit antibodies in the human host. Nevertheless, we can identify nine relatively well-conserved sporozoite proteins that elicit antibodies and that together can serve as markers for previous exposure. Our understanding of sporozoite biology benefits from identifying key pathways that are enriched during this life stage. This work can guide studies of molecular mechanisms underlying sporozoite biology and potential well-conserved targets for marker and drug development.

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7

Frischknecht, Friedrich y Kai Matuschewski. "Plasmodium Sporozoite Biology". Cold Spring Harbor Perspectives in Medicine 7, n.º 5 (20 de enero de 2017): a025478. http://dx.doi.org/10.1101/cshperspect.a025478.

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8

Sina, B. J., V. E. Dorosario, G. Woollett, K. Sakhuja y M. R. Hollingdale. "Plasmodium falciparum Sporozoite Immunization Protects against Plasmodium berghei Sporozoite Infection". Experimental Parasitology 77, n.º 2 (septiembre de 1993): 129–35. http://dx.doi.org/10.1006/expr.1993.1069.

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9

Toye, Philip, Antony Musoke y Jan Naessens. "Role of the Polymorphic Immunodominant Molecule in Entry of Theileria parva Sporozoites into Bovine Lymphocytes". Infection and Immunity 82, n.º 5 (18 de febrero de 2014): 1786–92. http://dx.doi.org/10.1128/iai.01029-13.

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ABSTRACTTheileria parvais a tick-transmitted apicomplexan parasite that infects cattle and African buffalo. In cattle, it causes a fatal lymphoproliferative disease called East Coast fever. The polymorphic immunodominant molecule (PIM) is expressed by two stages of the parasite: the sporozoite, which is inoculated by the tick to infect mammalian lymphocytes, and the schizont, the established intralymphocytic stage. Here, we demonstrate that monoclonal antibodies (MAb) to PIM can reduce the ability of sporozoites to infect bovine lymphocytesin vitro. This reduction appears to be due to blocking of sporozoite attachment by binding of the MAb to several regions of PIM. Interestingly, one MAb, which recognizes an epitope in the central variable region of PIM, did not inhibit sporozoite infectivity. We also demonstrate that PIM antigen, as a recombinant molecule, can also reduce sporozoite infectivityin vitroby blocking both attachment and internalization of sporozoites. Electron microscopic studies showed that PIM is present in microspheres below the sporozoite surface and is transported to the parasite surface soon after contact with bovine lymphocytes. The results suggest that at least two sporozoite molecules, PIM and the previously described p67, are involved in the entry ofT. parvainto mammalian lymphocytes.

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10

Cha, Sung-Jae, Kyle Jarrod McLean y Marcelo Jacobs-Lorena. "Identification of Plasmodium GAPDH epitopes for generation of antibodies that inhibit malaria infection". Life Science Alliance 1, n.º 5 (18 de septiembre de 2018): e201800111. http://dx.doi.org/10.26508/lsa.201800111.

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Plasmodium sporozoite liver infection is an essential step for parasite development in its mammalian host. Previously, we used a phage display library to identify mimotope peptides that bind to Kupffer cells and competitively inhibit sporozoite–Kupffer cell interaction. These peptides led to the identification of a Kupffer cell receptor—CD68—and a Plasmodium sporozoite ligand—GAPDH—that are required for sporozoite traversal of Kupffer cells and subsequent infection of hepatocytes. Here, we report that the C-terminal end of Plasmodium GAPDH interacts with the Kupffer CD68 receptor, and identify two epitopes within this region as candidate antigens for the development of antibodies that inhibit Plasmodium infection.

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11

ZECHINI, B., L. CORDIER, E. NGONSEU, U. D'ALESSANDRO, M. WERY y S. CHATTERJEE. "Plasmodium berghei development in irradiated sporozoite-immunized C57BL6 mice". Parasitology 118, n.º 4 (abril de 1999): 335–38. http://dx.doi.org/10.1017/s0031182099003959.

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The C57BL6 strain of mice is highly susceptible to Plasmodium berghei sporozoite infections and consequently requires repeated immunizations with irradiated sporozoites to obtain protective immunity. After a live sporozoite challenge in the immunized hosts, hepatic-stage parasites found in the liver after 48 h are of different sizes – small schizonts corresponding to blocked forms (derived from irradiated sporozoites), and schizonts of intermediate size (derived from live sporozoites). Large schizonts corresponding to mature hepatic forms are found only in unimmunized but challenged C57BL6 mice. Using monoclonal and polyclonal antibodies directed to liver-stage parasites, different patterns of binding reactivity to the above forms are observed. More than 20% of the irradiated sporozoites transform into blocked forms after immunization and persist in the liver. Upon sporozoite challenge in such immunized animals the rate of transformation of sporozoites into hepatic parasites is less than 2%. These observations shed light on the fate of live sporozoite development in irradiated sporozoite-immunized C57BL6 mice.

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12

Shaw, M. K. "Characterization of the parasite-host cell interactions involved inTheileria parvasporozoite invasion of bovine lymphocytes". Parasitology 113, n.º 3 (septiembre de 1996): 267–77. http://dx.doi.org/10.1017/s0031182000082032.

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SUMMARYSporozoite invasion of bovine lymphocytes byTheileria parvais a pH-dependent process that occurs without the need forde novoprotein synthesis. The process was inhibited by RGD(S) peptides, fibronectin and, in the presence of serum, by antibodies reactive with fibronectin. Invasion was also blocked by a range of sulphated glycoconjugates, but treatment of lymphocytes with heparitinase did not inhibit entry. Enzymic modifications of the lymphocyte surface demonstrated that trypsin-insensitive glycoproteins containingO- andN-linked carbohydrates as well as phospholipase-sensitive molecules on the host cell surface were critical to sporozoite entry. Modification of the lymphocyte surface with NEM and DTT had only marginal effects on sporozoite binding but blocked parasite internalization. Invasion was also blocked by several antibodies which cross-reacted with sporozoite surface molecules. While only a few experimental conditions specifically blocked sporozoite binding, a wider range of reagents and treatments inhibited parasite entry. The reasons for this are discussed in terms of the nature of the zippering process that facilitates sporozoite internalization.

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13

Rosario, Virgílio Do y Michael R. Hollingdale. "Prevalence of anti-p: Falciparum sporozoite antibodies in adults in the amapa region of Brazil". Revista do Instituto de Medicina Tropical de São Paulo 29, n.º 1 (febrero de 1987): 63–66. http://dx.doi.org/10.1590/s0036-46651987000100011.

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17 of 20 adult sera from the Amapa region of Brazil were active in the inhibition of P. falciparum sporozoite invasion (ISI) assay which has been correlated with protective antibodies. In contrast 11 sera were positive in IFA tests and 6 were positive in CSP tests. These results suggest that the ISI assay will be useful for evaluating naturally acquired protective anti-sporozoite antibodies in endemic areas, particularly during vaccine efficacy studies using sporozoite-based vaccines.

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14

Shaw, M. K., L. G. Tilney y A. J. Musoke. "The entry of Theileria parva sporozoites into bovine lymphocytes: evidence for MHC class I involvement." Journal of Cell Biology 113, n.º 1 (1 de abril de 1991): 87–101. http://dx.doi.org/10.1083/jcb.113.1.87.

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We have examined the process of Theileria parva sporozoite entry into susceptible bovine lymphocytes and have begun to identify one of the possible molecular interactions involved in the process. The entry process involves a defined series of events and we have used a number of experimental procedures in combination with a method of quantitation to examine various aspects of this process. T. parva sporozoites are nonmotile organisms and the initial sporozoite-lymphocyte interaction is a chance event which can occur at 0-2 degrees C. All subsequent stages in the process are temperature dependent, require the participation of live intact sporozoites and host cells, and involve some cytochalasin-inhibitable rearrangement of the host cell surface membrane or cytoskeleton. Sporozoite entry can be inhibited by antibodies (mAbs) reactive with major histocompatibility complex (MHC) class I molecules (IL-A 19, IL-A 88) and with beta 2 microglobulin (B1G6), whereas mAbs reactive with MHC class II molecules (IL-A 21, J 11), and a common panleucocyte surface antigen, (IL-A 87; a bovine equivalent of CD 11a) have no effect. These results indicate that MHC class I molecules play a role in the process of T. parva sporozoite entry into bovine lymphocytes although as yet the precise role has not been determined. Once internalized within the lymphocyte, a process that takes less than 3 min at 37 degrees C, the sporozoite rapidly escapes from the encapsulating host cell membrane; a process which occurs concurrently with the discharge of the contents of the sporozoite rhoptries and microspheres. The intracytoplasmic parasite is covered by a layer of sporozoite-derived fuzzy material to which host cell microtubules rapidly become associated.

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15

Cha, Sung-Jae, Min-Sik Kim, Akhilesh Pandey y Marcelo Jacobs-Lorena. "Identification of GAPDH on the surface of Plasmodium sporozoites as a new candidate for targeting malaria liver invasion". Journal of Experimental Medicine 213, n.º 10 (22 de agosto de 2016): 2099–112. http://dx.doi.org/10.1084/jem.20160059.

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Malaria transmission begins when an infected mosquito delivers Plasmodium sporozoites into the skin. The sporozoite subsequently enters the circulation and infects the liver by preferentially traversing Kupffer cells, a macrophage-like component of the liver sinusoidal lining. By screening a phage display library, we previously identified a peptide designated P39 that binds to CD68 on the surface of Kupffer cells and blocks sporozoite traversal. In this study, we show that the P39 peptide is a structural mimic of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) on the sporozoite surface and that GAPDH directly interacts with CD68 on the Kupffer cell surface. Importantly, an anti-P39 antibody significantly inhibits sporozoite liver invasion without cross-reacting with mammalian GAPDH. Therefore, Plasmodium-specific GAPDH epitopes may provide novel antigens for the development of a prehepatic vaccine.

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16

CAMPBELL, J. D., D. J. BROWN, E. J. GLASS, F. R. HALL y R. L. SPOONER. "Theileria annulata sporozoite targets". Parasite Immunology 16, n.º 9 (septiembre de 1994): 501–5. http://dx.doi.org/10.1111/j.1365-3024.1994.tb00378.x.

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17

Frevert, U. "Malaria Sporozoite-Hepatocyte Interactions". Experimental Parasitology 79, n.º 2 (septiembre de 1994): 206–10. http://dx.doi.org/10.1006/expr.1994.1082.

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18

Ash, C. "MICROBIOLOGY: Sinusoidal Sporozoite SPECTacle". Science 303, n.º 5661 (20 de febrero de 2004): 1106a—1106. http://dx.doi.org/10.1126/science.303.5661.1106a.

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19

Stewart, M. J., R. J. Nawrot, S. Schulman y J. P. Vanderberg. "Plasmodium berghei sporozoite invasion is blocked in vitro by sporozoite-immobilizing antibodies." Infection and Immunity 51, n.º 3 (1986): 859–64. http://dx.doi.org/10.1128/iai.51.3.859-864.1986.

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20

Khater, Emad I., Robert E. Sinden y Johannes T. Dessens. "A malaria membrane skeletal protein is essential for normal morphogenesis, motility, and infectivity of sporozoites". Journal of Cell Biology 167, n.º 3 (8 de noviembre de 2004): 425–32. http://dx.doi.org/10.1083/jcb.200406068.

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Membrane skeletons are structural elements that provide mechanical support to the plasma membrane and define cell shape. Here, we identify and characterize a putative protein component of the membrane skeleton of the malaria parasite. The protein, named PbIMC1a, is the structural orthologue of the Toxoplasma gondii inner membrane complex protein 1 (TgIMC1), a component of the membrane skeleton in tachyzoites. Using targeted gene disruption in the rodent malaria species Plasmodium berghei, we show that PbIMC1a is involved in sporozoite development, is necessary for providing normal sporozoite cell shape and mechanical stability, and is essential for sporozoite infectivity in insect and vertebrate hosts. Knockout of PbIMC1a protein expression reduces, but does not abolish, sporozoite gliding locomotion. We identify a family of proteins related to PbIMC1a in Plasmodium and other apicomplexan parasites. These results provide new functional insight in the role of membrane skeletons in apicomplexan parasite biology.

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21

Billman, Zachary P., Annette M. Seilie y Sean C. Murphy. "Purification of Plasmodium Sporozoites Enhances Parasite-Specific CD8+T Cell Responses". Infection and Immunity 84, n.º 8 (23 de mayo de 2016): 2233–42. http://dx.doi.org/10.1128/iai.01439-15.

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Malaria infection caused byPlasmodiumparasites continues to cause enormous morbidity and mortality in areas where it is endemic, and there is no licensed vaccine capable of inducing sterile protection. Hyperimmunization with attenuated whole sporozoites can induce sterile protective immune responses targeting preerythrocytic antigens. Most animal models of hyperimmunization rely on sporozoites dissected from mosquito salivary glands and injected without further purification. In BALB/c mice, repeated small doses ofP. yoeliisporozoites progressively expand the population of sporozoite-specific CD8+T cells. In this study, large secondary doses of unpurified sporozoites unexpectedly led to contraction of sporozoite-specific CD8+T cell responses in sporozoite-primed mice. While sporozoite-primed CD8+T cells alternatively can be expanded by secondary exposure toListeria monocytogenesexpressing recombinantPlasmodiumantigens, such expansion was potently inhibited by coinjection of large doses of unpurified sporozoites and by uninfected salivary glands alone. Purification of sporozoites away from mosquito salivary gland debris by density gradient centrifugation eliminated salivary gland-associated inhibition. Thus, the inhibitory effect appears to be due to exposure to uninfected mosquito salivary glands rather than sporozoites. To further assess the effect of salivary gland exposure on later sporozoite vaccinations, mice were immunized with uninfected salivary glands from a single mosquito. Compared to naive mice, salivary gland presensitization reduced subsequent liver burdens by 71%. These data show that a component(s) in mosquito salivary glands reduces liver infection, thereby limiting antigen dose and contributing to lower-magnitude T cell responses. These findings suggest that sporozoite immunogenicity studies be performed using purified sporozoites whenever feasible.

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22

McDonald, V., M. V. McCrossan y F. Petry. "Localization of parasite antigens inCryptosporidium parvum-infected epithelial cells using monoclonal antibodies". Parasitology 110, n.º 3 (abril de 1995): 259–68. http://dx.doi.org/10.1017/s0031182000080847.

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SUMMARYAn immunogold ultrastructural study was made ofCryptosporidium parvum-infected intestinal cells from SCID mice to locate parasite antigens recognized by monoclonal antibodies raised against sporozoite or oocyst wall antigens. The results suggested that these antigens were present in more than one life-cycle stage and demonstrated that the intracellular parasite modified the parasitophorous vacuole membrane and villous membrane surrounding the parasite. In an immuno-fluorescence antibody test monoclonal antibody (MAb) IB5 reacted with the oocyst wall, MAb 2C3 with the whole sporozoite and MAb 2B2 with the sporozoite surface. Western and dot-blot studies demonstrated that different carbohydrate epitopes were recognized by the respective sporozoite-reactive antibodies. In the ultrastructural examination MAb 1B5 reacted with macro- and microgametocytes as well as the oocyst wall. In the macrogametocyte MAb 1B5 recognized the large electron-dense bodies characteristic of this stage and, in some parasites, the parasitophorous vacuole and the parasite pellicle. The sporozoite-reactive MAbs were able to bind to all developmental stages. These antibodies recognized the parasite cytoplasm and, additionally, MAb 2B2 produced substantial labelling of the parasite membrane. Significantly, both these antibodies also detected antigen in the parasitophorous vacuole membrane and, to a lesser extent, the villous membrane surrounding the parasite.

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23

Tavares, Joana, Pauline Formaglio, Sabine Thiberge, Elodie Mordelet, Nico Van Rooijen, Alexander Medvinsky, Robert Ménard y Rogerio Amino. "Role of host cell traversal by the malaria sporozoite during liver infection". Journal of Experimental Medicine 210, n.º 5 (22 de abril de 2013): 905–15. http://dx.doi.org/10.1084/jem.20121130.

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Malaria infection starts when the sporozoite stage of the Plasmodium parasite is injected into the skin by a mosquito. Sporozoites are known to traverse host cells before finally invading a hepatocyte and multiplying into erythrocyte-infecting forms, but how sporozoites reach hepatocytes in the liver and the role of host cell traversal (CT) remain unclear. We report the first quantitative imaging study of sporozoite liver infection in rodents. We show that sporozoites can cross the liver sinusoidal barrier by multiple mechanisms, targeting Kupffer cells (KC) or endothelial cells and associated or not with the parasite CT activity. We also show that the primary role of CT is to inhibit sporozoite clearance by KC during locomotion inside the sinusoid lumen, before crossing the barrier. By being involved in multiple steps of the sporozoite journey from the skin to the final hepatocyte, the parasite proteins mediating host CT emerge as ideal antibody targets for vaccination against the parasite.

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24

Shaw, M. K., L. G. Tilney, A. J. Musoke y A. J. Teale. "MHC class I molecules are an essential cell surface component involved in Theileria parva sporozoite binding to bovine lymphocytes". Journal of Cell Science 108, n.º 4 (1 de abril de 1995): 1587–96. http://dx.doi.org/10.1242/jcs.108.4.1587.

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The major histocompatibility complex (MHC) class I molecules are ubiquitous cell surface molecules involved in the cell-mediated immune response. We show here, using a number of different, independent approaches, that these proteins are an essential component of the host cell surface receptor involved in Theileria parva sporozoite invasion. Monoclonal antibodies (mAbs) reactive with common determinants on MHC class I molecules and with beta-2 microglobulin inhibited sporozoite entry by specifically preventing the initial binding event. However, in experiments using lymphocytes from heterozygous cattle in which at least four MHC class I gene products are expressed, mAbs which reacted with only one of these products did not inhibit entry. Using a series of bovine deletion mutant cell lines from which one or both MHC class I haplotypes had been lost, sporozoite binding and entry clearly correlated with the level of class I surface expression. While the level of sporozoite entry into cells in which one of the MHC class I haplotypes was lost was only slightly lower than into the parent cells, in a double deletion cell line having less than 5% of the class I expression of the parent cells the level of infection was only 4.3% of that into the parent cells. Furthermore, sporozoite entry into cells from a spontaneously arising mutant cell line exhibiting low levels of class I expression was correspondingly low. Treatment of lymphocytes with IL-2 produced a significant increase in host cell susceptibility and sporozoite entry and this increase correlated with either an increase in the number of target molecules per host cell, or in the binding of bovine MHC class I molecules to the mAbs. In particular, a significant increase in the level of reactivity with mAb W6/32 was observed. Lastly, we show that parasite entry can be competitively inhibited with an isolated sporozoite surface protein, p67. However, p67 binds weakly to lymphocyte surface molecules and initial attempts to use p67 to isolate the relevant host cell molecule(s) have not been successful.

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25

Engelmann, Sabine, Olivier Silvie y Kai Matuschewski. "Disruption of Plasmodium Sporozoite Transmission by Depletion of Sporozoite Invasion-Associated Protein 1". Eukaryotic Cell 8, n.º 4 (30 de enero de 2009): 640–48. http://dx.doi.org/10.1128/ec.00347-08.

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ABSTRACT Accumulation of infectious Plasmodium sporozoites in Anopheles spp. salivary glands marks the final step of the complex development of the malaria parasite in the insect vector. Sporozoites are formed inside midgut-associated oocysts and actively egress into the mosquito hemocoel. Traversal of the salivary gland acinar cells correlates with the sporozoite's capacity to perform continuous gliding motility. Here, we characterized the cellular role of the Plasmodium berghei sporozoite invasion-associated protein 1 (SIAP-1). Intriguingly, SIAP-1 orthologs are found exclusively in apicomplexan hemoprotozoa, parasites that are transmitted by arthropod vectors, e.g., Plasmodium, Babesia, and Theileria species. By fluorescent tagging with mCherry, we show that SIAP-1 is expressed in oocyst-derived and salivary gland-associated sporozoites, where it accumulates at the apical tip. Targeted disruption of SIAP-1 does not affect sporozoite formation but causes a partial defect in sporozoite egress from oocysts and abolishes sporozoite colonization of mosquito salivary glands. Parasites with the siap-1(−) mutation are blocked in their capacity to perform continuous gliding motility. We propose that arthropod-transmitted apicomplexan parasites specifically express secretory factors, such as SIAP-1, that mediate efficient oocyst exit and migration to the salivary glands.

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26

HOGG, J. C. y H. HURD. "The effects of natural Plasmodium falciparum infection on the fecundity and mortality of Anopheles gambiae s. l. in north east Tanzania". Parasitology 114, n.º 4 (abril de 1997): 325–31. http://dx.doi.org/10.1017/s0031182096008542.

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Rodent and avian malaria parasites have been reported to have an adverse affect upon the reproductive fitness of mosquitoes. In order to determine whether fecundity reduction occurs in Anopheles gambiae s. l. infected with human malaria a study of wild-caught mosquitoes was undertaken in the Muheza district of north east Tanzania. Fully engorged, indoor resting females were collected daily for 4 months and maintained for 5 days. A sporozoite rate of 11·5% was detected for the whole collection and of those females alive on day 6 an additional 17·5% were infected with oocysts alone. Oocyst, but not sporozoite, infection resulted in a 17·5% reduction in egg production. Fecundity reduction was not caused by a reduction in bloodmeal size in infected females and no size difference was detected between oocyst-infected and uninfected females although sporozoite-positive females were significantly larger. Comparisons in parity between uninfected and infected groups indicate that infection does not affect survival beyond the first gonotrophic cycle as no changes in survivorship occurred as a result of sporozoite infection.

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27

Panchal, Dhruv y Purnima Bhanot. "Activity of a Trisubstituted Pyrrole in Inhibiting Sporozoite Invasion and Blocking Malaria Infection". Antimicrobial Agents and Chemotherapy 54, n.º 10 (19 de julio de 2010): 4269–74. http://dx.doi.org/10.1128/aac.00420-10.

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ABSTRACT Malaria infection is initiated by Plasmodium sporozoites infecting the liver. Preventing sporozoite infection would block the obligatory first step of the infection and perhaps reduce disease severity. In addition, such an approach would decrease P lasmodium vivax hypnozoite formation and therefore disease relapses. Here we describe the activity of a trisubstituted pyrrole, 4-[2-(4-fluorophenyl)-5-(1-methylpiperidine-4-yl)-1H-pyrrol-3-yl] pyridine, in inhibiting motility, invasion, and consequently infection by P. berghei sporozoites. In tissue culture, the compound was effective within the first 3 h of sporozoite addition to HepG2 cells. In vivo, intraperitoneal administration of the compound significantly inhibited liver-stage parasitemia in P. yoelii sporozoite-infected mice and prevented the appearance of blood-stage parasites. P. berghei sporozoites lacking the parasite cGMP-dependent protein kinase, the primary target of the compound in erythrocyte-stage parasites, remained infectious to HepG2 cells and sensitive to the drug. These results suggest that the drug has an additional target(s) in sporozoites. We propose that drugs that inhibit sporozoite infection offer a feasible approach to malaria prophylaxis.

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28

Hamilton, A. J., C. S. Davies y R. E. Sinden. "Expression of circumsporozoite proteins revealed in situ in the mosquito stages of Plasmodium berghei by the Lowicryl-immunogold technique". Parasitology 96, n.º 2 (abril de 1988): 273–80. http://dx.doi.org/10.1017/s0031182000058273.

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SummaryA monoclonal antibody against the circumsporozoite proteins of the Plasmodium berghei sporozoite was used to trace the synthesis and expression of these proteins, via the Lowicryl immunogold technique, within the developing oocyst. The proteins were detected on the endoplasmic reticulum of the oocyst and were present in the sporozoite membranes at the point of their formation.

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29

Cha, Sung-Jae, Kiwon Park, Prakash Srinivasan, Christian W. Schindler, Nico van Rooijen, Monique Stins y Marcelo Jacobs-Lorena. "CD68 acts as a major gateway for malaria sporozoite liver infection". Journal of Experimental Medicine 212, n.º 9 (27 de julio de 2015): 1391–403. http://dx.doi.org/10.1084/jem.20110575.

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After being delivered by the bite from an infected mosquito, Plasmodium sporozoites enter the blood circulation and infect the liver. Previous evidence suggests that Kupffer cells, a macrophage-like component of the liver blood vessel lining, are traversed by sporozoites to initiate liver invasion. However, the molecular determinants of sporozoite–Kupffer cell interactions are unknown. Understanding the molecular basis for this specific recognition may lead to novel therapeutic strategies to control malaria. Using a phage display library screen, we identified a peptide, P39, that strongly binds to the Kupffer cell surface and, importantly, inhibits sporozoite Kupffer cell entry. Furthermore, we determined that P39 binds to CD68, a putative receptor for sporozoite invasion of Kupffer cells that acts as a gateway for malaria infection of the liver.

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30

SKILTON, R. A., A. J. MUSOKE, C. W. WELLS, Y. YAGI, V. NENE, P. R. SPOONER, J. GACHANJA, J. OSASO, R. P. BISHOP y S. P. MORZARIA. "A 32 kDa surface antigen of Theileria parva: characterization and immunization studies". Parasitology 120, n.º 6 (junio de 2000): 553–64. http://dx.doi.org/10.1017/s0031182099005934.

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Previous studies using monoclonal antibody (mAb) 4C9 specific for a 32 kDa antigen (p32) of Theileria parva demonstrated expression of the antigen on the surface of the sporozoite, making it a potential antigen for sporozoite neutralization. A full-length cDNA encoding the major merozoite/piroplasm surface antigen (mMPSA) of T. parva was cloned and expressed in bacteria. The expressed product reacted strongly with mAb 4C9, demonstrating identity between the p32 and mMPSA of T. parva. Using immunoblot analysis and immunoelectron microscopy with mAb 4C9 it was shown that the mMPSA is a major antigen of the merozoite and piroplasm at the cell surface, while lower levels of antigen are expressed in the sporozoite and schizont stages. Upregulation of the mMPSA occurs at merogony and can be induced by culturing schizont-infected lymphocytes at 42 °C. Recombinant mMPSA of T. parva induced high titres of specific antibodies in cattle but failed to confer protection against a T. parva sporozoite stabilate challenge. The pre-challenge sera also failed to neutralize infectivity of sporozoites in an in vitro assay. Possible reasons for the lack of parasite neutralization in vivo and in vitro are discussed.

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31

Taylor-Robinson, Andrew. "Malaria sporozoite rite of passage". Trends in Parasitology 17, n.º 4 (abril de 2001): 165. http://dx.doi.org/10.1016/s1471-4922(01)01930-4.

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32

Montagna, Georgina, N. "Plasmodium sporozoite motility: an update". Frontiers in Bioscience 17, n.º 1 (2012): 726. http://dx.doi.org/10.2741/3954.

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33

Nussenzweig, R. S. y V. Nussenzweig. "Development of a sporozoite vaccine". Parasitology Today 1, n.º 6 (diciembre de 1985): 150–52. http://dx.doi.org/10.1016/0169-4758(85)90170-x.

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34

Birley, M. H. y J. D. Charlewood. "Sporozoite rate and malaria prevalence". Parasitology Today 3, n.º 8 (agosto de 1987): 231–32. http://dx.doi.org/10.1016/0169-4758(87)90145-1.

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35

McCutchan, T. F. "Ribosomal RNA for sporozoite detection". Parasitology Today 4, n.º 4 (abril de 1988): 106. http://dx.doi.org/10.1016/0169-4758(88)90036-1.

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36

Vaughan, Jefferson A., Libia F. Scheller, Robert A. Wirtz y Abdu F. Azad. "Infectivity of Plasmodium bergheiSporozoites Delivered by Intravenous Inoculation versus Mosquito Bite: Implications for Sporozoite Vaccine Trials". Infection and Immunity 67, n.º 8 (1 de agosto de 1999): 4285–89. http://dx.doi.org/10.1128/iai.67.8.4285-4289.1999.

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ABSTRACT Plasmodium berghei sporozoites delivered by mosquito bite were more infectious to outbred CD-1 mice than were sporozoites delivered by intravenous inoculation. The route of challenge also affected vaccine efficacy. In view of these findings and the fact that mosquito bites are the natural mode of sporozoite delivery, infectious mosquito bites should be considered the challenge protocol of choice for sporozoite vaccine efficacy trials.

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37

SKILTON, R. A., R. P. BISHOP, C. W. WELLS, P. R. SPOONER, E. GOBRIGHT, C. NKONGE, A. J. MUSOKE, M. MACKLIN y K. P. IAMS. "Cloning and characterization of a 150 kDa microsphere antigen of Theileria parva that is immunologically cross-reactive with the polymorphic immunodominant molecule (PIM)". Parasitology 117, n.º 4 (octubre de 1998): 321–30. http://dx.doi.org/10.1017/s0031182098003163.

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To identify the genes encoding novel immunodominant antigens of Theileria parva a λgt11 library of piroplasm genomic DNA was immunoscreened with bovine recovery serum and a gene encoding a 150 kDa antigen (p150) was identified. The predicted polypeptide contains an N-terminal secretory signal sequence and a proline-rich region of repeated amino acid motifs. The repeat region is polymorphic between stocks of T. parva in both copy number and sequence, and analysis of the repeat region from 10 stocks of T. parva revealed 5 p150 variants. A monoclonal antibody (mAb) against the T. parva polymorphic immunodominant molecule (PIM) cross-reacted with the recombinant p150. The p150 has sequence homology with a PIM peptide sequence containing the anti-PIM mAb epitope. Immunoelectron microscopy demonstrated that the p150 antigen, like PIM, is located in the microspheres of the sporozoites and is exocytosed following sporozoite invasion of the host lymphocyte. By immunoelectron microscopy p150 was subsequently transiently detectable on the sporozoite surface and in the lymphocyte cytosol. Immunoblotting showed that p150 is also expressed by the schizont stage, but at much lower levels compared to the sporozoite. These results suggest a major role for p150 in the early events of host–sporozoite interaction.

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38

Coppi, Alida, Ramya Natarajan, Gabriele Pradel, Brandy L. Bennett, Eric R. James, Mario A. Roggero, Giampietro Corradin, Cathrine Persson, Rita Tewari y Photini Sinnis. "The malaria circumsporozoite protein has two functional domains, each with distinct roles as sporozoites journey from mosquito to mammalian host". Journal of Experimental Medicine 208, n.º 2 (24 de enero de 2011): 341–56. http://dx.doi.org/10.1084/jem.20101488.

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Plasmodium sporozoites make a remarkable journey from the mosquito midgut to the mammalian liver. The sporozoite’s major surface protein, circumsporozoite protein (CSP), is a multifunctional protein required for sporozoite development and likely mediates several steps of this journey. In this study, we show that CSP has two conformational states, an adhesive conformation in which the C-terminal cell-adhesive domain is exposed and a nonadhesive conformation in which the N terminus masks this domain. We demonstrate that the cell-adhesive domain functions in sporozoite development and hepatocyte invasion. Between these two events, the sporozoite must travel from the mosquito midgut to the mammalian liver, and N-terminal masking of the cell-adhesive domain maintains the sporozoite in a migratory state. In the mammalian host, proteolytic cleavage of CSP regulates the switch to an adhesive conformation, and the highly conserved region I plays a critical role in this process. If the CSP domain architecture is altered such that the cell-adhesive domain is constitutively exposed, the majority of sporozoites do not reach their target organs, and in the mammalian host, they initiate a blood stage infection directly from the inoculation site. These data provide structure–function information relevant to malaria vaccine development.

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39

Harupa, Anke, Brandon K. Sack, Viswanathan Lakshmanan, Nadia Arang, Alyse N. Douglass, Brian G. Oliver, Andrew B. Stuart et al. "SSP3 Is a Novel Plasmodium yoelii Sporozoite Surface Protein with a Role in Gliding Motility". Infection and Immunity 82, n.º 11 (25 de agosto de 2014): 4643–53. http://dx.doi.org/10.1128/iai.01800-14.

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ABSTRACTPlasmodiumsporozoites develop within oocysts in the mosquito midgut wall and then migrate to the salivary glands. After transmission, they embark on a complex journey to the mammalian liver, where they infect hepatocytes. Proteins on the sporozoite surface likely mediate multiple steps of this journey, yet only a few sporozoite surface proteins have been described. Here, we characterize a novel, conserved sporozoite surface protein (SSP3) in the rodent malaria parasitePlasmodium yoelii. SSP3 is a putative type I transmembrane protein unique toPlasmodium. By using epitope tagging and SSP3-specific antibodies in conjunction with immunofluorescence microscopy, we showed that SSP3 is expressed in mosquito midgut oocyst sporozoites, exhibiting an intracellular localization. In sporozoites derived from the mosquito salivary glands, however, SSP3 localized predominantly to the sporozoite surface as determined by immunoelectron microscopy. However, the ectodomain of SSP3 appeared to be inaccessible to antibodies in nonpermeabilized salivary gland sporozoites. Antibody-induced shedding of the major surface protein circumsporozoite protein (CSP) exposed the SSP3 ectodomain to antibodies in some sporozoites. Targeted deletion ofSSP3adversely affectedin vitrosporozoite gliding motility, which, surprisingly, impacted neither their cell traversal capacity, host cell invasionin vitro, nor infectivityin vivo. Together, these data reveal a previously unappreciated complexity of thePlasmodiumsporozoite surface proteome and the roles of surface proteins in distinct biological activities of sporozoites.

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40

Pumpuni, Charles B., Chandana Mendis y John C. Beier. "Plasmodium yoelii Sporozoite Infectivity Varies as a Function of Sporozoite Loads in Anopheles stephensi Mosquitoes". Journal of Parasitology 83, n.º 4 (agosto de 1997): 652. http://dx.doi.org/10.2307/3284242.

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41

Rogers, William O., Miriam D. Rogers, Richard C. Hedstrom y Stephen L. Hoffman. "Characterization of the gene encoding sporozoite surface protein 2, a protective Plasmodium yoelii sporozoite antigen". Molecular and Biochemical Parasitology 53, n.º 1-2 (julio de 1992): 45–51. http://dx.doi.org/10.1016/0166-6851(92)90005-5.

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42

Armistead, Jennifer S., Iain B. H. Wilson, Toin H. van Kuppevelt y Rhoel R. Dinglasan. "A role for heparan sulfate proteoglycans in Plasmodium falciparum sporozoite invasion of anopheline mosquito salivary glands". Biochemical Journal 438, n.º 3 (26 de agosto de 2011): 475–83. http://dx.doi.org/10.1042/bj20110694.

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HS (heparan sulfate) has been shown to be an important mediator of Plasmodium sporozoite homing and invasion of the liver, but the role of this glycosaminoglycan in mosquito vector host–sporozoite interactions is unknown. We have biochemically characterized the function of AgOXT1 (Anopheles gambiae peptide-O-xylosyltransferase 1) and confirmed that AgOXT1 can modify peptides representing model HS and chondroitin sulfate proteoglycans in vitro. Moreover, we also demonstrated that the mosquito salivary gland basal lamina proteoglycans are modified by HS. We used RNA interference-mediated knockdown of HS biosynthesis in A. gambiae salivary glands to determine whether Plasmodium falciparum sporozoites that are released from mosquito midgut oocysts use salivary gland HS as a receptor for tissue invasion. Our results suggest that salivary gland basal lamina HS glycosaminoglycans only partially mediate midgut sporozoite invasion of this tissue, and that in the absence of HS, the presence of other surface co-receptors is sufficient to facilitate parasite entry.

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43

Aley, S. B., M. D. Bates, J. P. Tam y M. R. Hollingdale. "Synthetic peptides from the circumsporozoite proteins of Plasmodium falciparum and Plasmodium knowlesi recognize the human hepatoma cell line HepG2-A16 in vitro." Journal of Experimental Medicine 164, n.º 6 (1 de diciembre de 1986): 1915–22. http://dx.doi.org/10.1084/jem.164.6.1915.

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Several lines of evidence have emphasized the importance of the malaria circumsporozoite (CS) protein as a factor in sporozoite invasion of the hepatocyte; however, the specific mechanism of cell recognition and invasion has not been explained. In this study we present evidence that a highly conserved region of the CS protein immediately adjacent to the repeat region, the N1 region, specifically recognizes receptors on the human hepatoma cell line HepG2-A16 under conditions where invasion by sporozoites can occur. Peptides consisting of sequences from the repeat region or of the more extensive N2 region showed no such specific association. Antibody against the N1 peptide could inhibit sporozoite invasion in vitro. Covalent coupling of radiolabeled N1 peptide to HepG2-A16 cells identified two hepatic cell proteins to be closely associated with the peptide. We suggest that these proteins could act as receptors or mediators, via the N1 region of the CS protein, for the P. falciparum sporozoite in the process of invasion of the hepatocyte.

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44

Nussenzweig, Victor y Ruth S. Nussenzweig. "Development of a Sporozoite Malaria Vaccine". American Journal of Tropical Medicine and Hygiene 35, n.º 4 (1 de julio de 1986): 678–88. http://dx.doi.org/10.4269/ajtmh.1986.35.678.

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45

Nussenzweig, Victor y Ruth S. Nussenzweig. "Development of a sporozoite malaria vaccine". Memórias do Instituto Oswaldo Cruz 81, suppl 2 (1986): 45–55. http://dx.doi.org/10.1590/s0074-02761986000600008.

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46

Silvie, O. "Malaria sporozoite: migrating for a living". Trends in Molecular Medicine 10, n.º 3 (marzo de 2004): 97–100. http://dx.doi.org/10.1016/j.molmed.2004.01.004.

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47

Krettli, Antoniana U. y Louis H. Miller. "Malaria: A sporozoite runs through it". Current Biology 11, n.º 10 (mayo de 2001): R409—R412. http://dx.doi.org/10.1016/s0960-9822(01)00221-4.

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48

Hollingdale, Michael R. y Martha Sedegah. "Development of whole sporozoite malaria vaccines". Expert Review of Vaccines 16, n.º 1 (18 de julio de 2016): 45–54. http://dx.doi.org/10.1080/14760584.2016.1203784.

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49

Vignali, Marissa, Cate Speake y Patrick E. Duffy. "Malaria sporozoite proteome leaves a trail". Genome Biology 10, n.º 4 (2009): 216. http://dx.doi.org/10.1186/gb-2009-10-4-216.

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50

Chulay, Jeffrey D. "Development of sporozoite vaccines for malaria". Transactions of the Royal Society of Tropical Medicine and Hygiene 83 (enero de 1989): 61–66. http://dx.doi.org/10.1016/0035-9203(89)90606-8.

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