Studies on tropical theileriosis in Turkey 5. Studies on Various Numbers of Attenuated Vaccine Cells Used in Cattle Against Tropical Theileriosis

Authors: FAHRİ SAYIN, SERPİL NALBANTOĞLU, K. ZAFER KARAER, AYŞE ÇAKMAK, ŞÜKRAN DİNÇER, ZATİ VATANSEVER, ABDULLAH İNCİ, BAYRAM ALİ YUKARI, HASAN EREN, METİN GÜNAY, ERKUT ONAR, HATİCE ALP

Abstract: Since the total of 150,000 doses of attenuated cell culture vaccine doses produced anually in Turkey does not meet the requirements of the country, by reducing the number of vaccine cells in a single dose, an increased number of vaccine doses was obtained for cattle, and doses consisting of different numbers of vaccine cells were tested according to their protective efficiency against tropical theileriosis in cattle. Fifty Holstein calves aged 2.5-3 months were used: 42 of them were used in vaccine dose trials while 8 were used in the determination of pathogenicity of the challenge material. In order to examine doses consisting of different numbers of vaccine cells, 3 experiments were carried out. Three groups (including 1 control) consisting of 4 calves were formed in the first experiment while 5 groups (including 1 control) consisting of 3 calves were formed in the second experiment and 2 groups consisting of 10 and 5 (control) calves were formed in the third experiment. Calves in the first experiment groups were vaccinated with 10^6 and 10^7 vaccine cells, whereas calves in the second experiment groups were vaccinated with 10^3, 10^4, 10^5 and 10^6 and calves in the third experiment groups were vaccinated with 10^6 cells. Animals in the control groups were not vaccinated. Generally, significant reactions were not observed in vaccinated calves and neither schizonts in lymph node smears nor piroplasm forms in blood smears were detected in any of them. No difference was observed in blood cell levels. Thirty-five days after vaccination, animal groups including the control groups were challenged with Theileria annulata Sarıoba Hyalomma detritum tick stabilate (4 t.e.) in the first experiment, T. annulata Akdere H. detritum tick stabilate (4 t.e.) in the second experiment and T. annulata AKSA H. anatolicum anatolicum (4 t.e./1 ml T. annulata Akdere + 4 t.e./1 ml T. annulata Sarıoba) tick stabilate (prepared from 8 ticks) in the third experiment. Infection developed in both vaccinated and non-vaccinated calves following challenge and schizonts, piroplasms and fever were observed. When compared to vaccinated calves, parasitaemia and schizont levels and body temperatures were higher and clinical reactions were more severe in non-vaccinated calves. Vaccinated and non-vaccinated calves in the third experiment groups, which were challenged with higher material levels, exhibited more severe infection symptoms compared to the first 2 experiment groups. Higher levels of schizont and piroplasms were detected in the animal groups in the third experiment, and 4 of the vaccinated calves (40%) and all control calves (100%) died from tropical theileriosis. In conclusion, vaccines applied at 10^3, 10^4, 10^5, 10^6 and 10^7 cell doses were found to protect cattle from infection in this research. No significant difference was detected between the protective efficiacy of vaccine doses. However, in cases in which tick challenge was higher, the 10^6 cell vaccine dose was found to be insufficient regarding protection.

Keywords: Theileria annulata, theileriosis, vaccination, cattle

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