The Experts below are selected from a list of 159 Experts worldwide ranked by ideXlab platform
V. Shkap - One of the best experts on this subject based on the ideXlab platform.
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Vaccination against Tropical Theileriosis
Annals of the New York Academy of Sciences, 2006Co-Authors: E. Pipano, V. ShkapAbstract:Theileria annulata, the cause of tropical theileriosis is propagated in cattle with stage-to-stage transmission by Hyalomma ticks. Three stages in the life cycle of the parasite--tick-derived sporozoites, intramononuclear Schizonts, and erythrocytic merozoites--infect cattle. When cattle are inoculated with Schizont-infected cells, the parasite is transferred from the donor cell to the recipient. The main pathological damage in cattle is induced by the Schizont stage. Each development stage of T. annulata elicits a specific immune response. Schizont-infected lymphoid cells can be grown indefinitely in culture and prolonged cultivation results in loss of virulence. Blood-derived Schizonts induce stronger immunity than culture-derived Schizonts, which suggests that restrictions on the parasite population or antigenic variation occur during prolonged cultivation. The duration of immunity following sporozoite or Schizont infections has not yet been determined, but does not appear to be lifelong. The attenuated, culture-derived anti-theileria vaccine proved to be safe and effective in prevention of field theileriosis in large enzootic areas.
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Proteolytic enzyme activity and attenuation of virulence in Theileria annulata Schizont-infected cells
Veterinary parasitology, 2003Co-Authors: V. Shkap, E. Pipano, I. Rasulov, D. Azimov, I. Savitsky, L. Fish, Y. Krigel, B. LeibovitchAbstract:A field isolate of Theileria annulata (Uzbek strain) was obtained from calves infected by Hyalomma anatolicum ticks collected from an endemic region in Uzbekistan. Schizont-infected bovine cells that had been established and propagated in cell culture were examined for attenuation both in vivo, by inoculating cells from various passages into calves, and in vitro for metalloproteinase activity. During serial subcultivation a gradual reduction in virulence and in enzyme activity in cells infected with the Uzbek strain were observed. Complete attenuation of the Uzbek isolate was obtained at about passage 80, and only traces of proteolysis were detected in gelatin substrate gels. In contrast, there was no direct correlation between virulence and enzyme levels in an Israeli strain. While Schizonts of the Israeli strain were completely attenuated at passage 80, proteolysis in the substrate gels was detected up to passage 197. Solid immunity was observed in calves immunized with attenuated T. annulata Schizonts of the Uzbek strain upon challenge with the homologous H. excavatum sporozoites. For a strain to be used for vaccine production, it appears that animal inoculation still remains the most reliable method to assess the degree of attenuation and protection.
Qi Bai - One of the best experts on this subject based on the ideXlab platform.
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Observation on the Schizont stage of an unidentified Theileria sp. in experimentally infected sheep.
Parasitology research, 2003Co-Authors: Hong Yin, Guangyuan Liu, Jianxun Luo, Guiquan Guan, Jabbar S. Ahmed, Qi BaiAbstract:The Schizont stage of an unidentified Theileria sp. infective for small ruminants was observed. Intact sheep were infected with adult Haemaphysalis qinghaiensis collected from fields where ovine theileriosis was prevalent. When the infested sheep developed theileriosis, tissue and organ smears were prepared. Theileria Schizonts were demonstrated in liver, spleen, lung, kidney, lymph node and peripheral blood. Most of the Schizonts were found outside the host cells, which was probably a smear artifact. This study adds our knowledge that lung and kidney can be parasitized by Schizonts of Theileria sp.
E. Pipano - One of the best experts on this subject based on the ideXlab platform.
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Vaccination against Tropical Theileriosis
Annals of the New York Academy of Sciences, 2006Co-Authors: E. Pipano, V. ShkapAbstract:Theileria annulata, the cause of tropical theileriosis is propagated in cattle with stage-to-stage transmission by Hyalomma ticks. Three stages in the life cycle of the parasite--tick-derived sporozoites, intramononuclear Schizonts, and erythrocytic merozoites--infect cattle. When cattle are inoculated with Schizont-infected cells, the parasite is transferred from the donor cell to the recipient. The main pathological damage in cattle is induced by the Schizont stage. Each development stage of T. annulata elicits a specific immune response. Schizont-infected lymphoid cells can be grown indefinitely in culture and prolonged cultivation results in loss of virulence. Blood-derived Schizonts induce stronger immunity than culture-derived Schizonts, which suggests that restrictions on the parasite population or antigenic variation occur during prolonged cultivation. The duration of immunity following sporozoite or Schizont infections has not yet been determined, but does not appear to be lifelong. The attenuated, culture-derived anti-theileria vaccine proved to be safe and effective in prevention of field theileriosis in large enzootic areas.
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Proteolytic enzyme activity and attenuation of virulence in Theileria annulata Schizont-infected cells
Veterinary parasitology, 2003Co-Authors: V. Shkap, E. Pipano, I. Rasulov, D. Azimov, I. Savitsky, L. Fish, Y. Krigel, B. LeibovitchAbstract:A field isolate of Theileria annulata (Uzbek strain) was obtained from calves infected by Hyalomma anatolicum ticks collected from an endemic region in Uzbekistan. Schizont-infected bovine cells that had been established and propagated in cell culture were examined for attenuation both in vivo, by inoculating cells from various passages into calves, and in vitro for metalloproteinase activity. During serial subcultivation a gradual reduction in virulence and in enzyme activity in cells infected with the Uzbek strain were observed. Complete attenuation of the Uzbek isolate was obtained at about passage 80, and only traces of proteolysis were detected in gelatin substrate gels. In contrast, there was no direct correlation between virulence and enzyme levels in an Israeli strain. While Schizonts of the Israeli strain were completely attenuated at passage 80, proteolysis in the substrate gels was detected up to passage 197. Solid immunity was observed in calves immunized with attenuated T. annulata Schizonts of the Uzbek strain upon challenge with the homologous H. excavatum sporozoites. For a strain to be used for vaccine production, it appears that animal inoculation still remains the most reliable method to assess the degree of attenuation and protection.
W.i. Morrison - One of the best experts on this subject based on the ideXlab platform.
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Characterization of a polymorphic immunodominant molecule in sporozoites and Schizonts of Theileria parva
Parasite Immunology, 1991Co-Authors: Philip G Toye, K. Iams, Antony Musoke, Bruno Goddeeris, W.i. MorrisonAbstract:Summary This study examines several aspects of a polymorphic, immunodominant molecule (P!M) found in the protozoan parasite. Theileria parva. The antigen is present in all T. p. parva stocks examined, and in the related subspecies, T. p. bovis and T. p. lawrencei. It is the predominant antigen recognized by antisera from immune cattle on Western blot analysis of Schizont-infected lymphocytes, and is the only antigen which has been shown to react with anti-Schizont monoclonal antibodies (MoAbs) on Western blots or in immunoprecipitations. The antigen shows polymorphism in both size and expression of antibody epitopes among the different stocks of T. parva. The antigen is present in sporozoites as well as Schizonts.
B. Leibovitch - One of the best experts on this subject based on the ideXlab platform.
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Proteolytic enzyme activity and attenuation of virulence in Theileria annulata Schizont-infected cells
Veterinary parasitology, 2003Co-Authors: V. Shkap, E. Pipano, I. Rasulov, D. Azimov, I. Savitsky, L. Fish, Y. Krigel, B. LeibovitchAbstract:A field isolate of Theileria annulata (Uzbek strain) was obtained from calves infected by Hyalomma anatolicum ticks collected from an endemic region in Uzbekistan. Schizont-infected bovine cells that had been established and propagated in cell culture were examined for attenuation both in vivo, by inoculating cells from various passages into calves, and in vitro for metalloproteinase activity. During serial subcultivation a gradual reduction in virulence and in enzyme activity in cells infected with the Uzbek strain were observed. Complete attenuation of the Uzbek isolate was obtained at about passage 80, and only traces of proteolysis were detected in gelatin substrate gels. In contrast, there was no direct correlation between virulence and enzyme levels in an Israeli strain. While Schizonts of the Israeli strain were completely attenuated at passage 80, proteolysis in the substrate gels was detected up to passage 197. Solid immunity was observed in calves immunized with attenuated T. annulata Schizonts of the Uzbek strain upon challenge with the homologous H. excavatum sporozoites. For a strain to be used for vaccine production, it appears that animal inoculation still remains the most reliable method to assess the degree of attenuation and protection.
