Assessment of Profile of Antigenicity and Immunogenicity of Eimeria maxima and Eimeria tenella through Propagative Level and Histopathological Changes in Site Infection for Exploration of Optimal Low Doses of Bivalent Chicken Coccidiosis Live Vaccine

摘要

Live vaccines group was the first to be studied, due to the fact that live parasites reduce further reinfection. The development of vaccine to control coccidiosis caused by E. maxima and E. tenella in chickens is intensifying because of the increasing threat of drug resistance to anticoccidial agents. It is important, therefore, to develop a reliable standard method for the assessment of vaccine afficacy particularly antigenicity and immunogenicity become crucial. Evaluation of profile of antigenicity and immunogenicity of E. maxima and E. tenella to some low doses can be reflected through propagative level and histopathological changes. The complete random design of research was used in this study. Sixty of two weeks old broilers were divided into four groups and each group composed 15 replications. The group 1 and group 2 were chicken group inoculated orally 5 × 102 and 1 × 103 virulent E. maxima oocysts, respectively. The group 3 and group 4 were chicken group inoculated with 2.5 × 102 and 5 × 102 virulent E. tenella oocysts, respectively. Then all chickens of group 1 and group 2 were challenged with E. maxima oocyst at doses of 5 × 103, while chicken group 3 and group 4 were challenged with E. tenella oocyst at doses of 2.5 × 103. Observation of research that represented antigenicity and immunogenicity was clinical sign, propagative level, histopathological changes. On primary inoculation, chicken group 1 and 3 which low doses of E. maxima and E. tenella respectively inoculated was some clinical signs such as appetite, weakness, and diarrhea were not seen on all chicken, low parasite propagative level and few histopathological changes on development site, whereas on group 2 and 4 which higher doses of E. maxima and E. tenella respectively inoculated was appeared clinical signs such as appetite, weakness, and diarrhea, moderate parasite propagative level and histopathological changes on development site. Then on challenge test, group 1 and 2 which challenged E. maxima and group 3 and 4 which challenged E. tenella showed there were no clinical signs such as appetite, weakness, and diarrhea on all chicken groups. For the propagative level and histopathological changes, there were no significantly differences in all chicken groups. We concluded that the low doses of virulent E. maxima and E. tenella had low propagative level and few histopathological changes effect that represents a promising strategy to prevent chickens coccidiosis particularly both species.