Protection of cattle against Theileria annulata infection using Corynebacterium parvum.

Four groups of calves (A, B, C and D) each consisting of five calves were used for the present study. Group A calves were given Corynebacterium parvum alone. Group B calves were inoculated with inactivated ground-up-tick supernate (GUTS) prepared from Hyalomma anatolicum anatolicum infected with Theileria annulata plus C. parvum. Group C received only inactivated GUTS. All the surviving calves of groups A to C were exposed on day 45 post-inoculation to a lethal tick challenge along with susceptible control calves of group D. All the calves of groups A and B withstood the challenge whereas all the calves of groups C and D died of theileriosis. Complement fixing antibodies were detected in calves of groups B and C. A significant decrease in neutrophils and a significant increase in monocytes was observed in calves of groups A and B. No significant changes were seen in other cell types. The results of this study demonstrated that C. parvum alone may be used as an immunostimulant for producing non-specific resistance against T. annulata.