Vaccine potential of recombinant antigens of Theileria annulata and Hyalomma anatolicum anatolicum against vector and parasite

In an attempt to develop vaccine against Hyalomma anatolicum anatolicum and Theileria annulata, three antigens were expressed in prokaryotic expression system and protective potentiality of the antigens was evaluated in cross bred calves. Two groups (grs. 1 and 4) of male cross-bred (Bos indicus × Bos taurus) calves were immunized with rHaa86, a Bm86 ortholog of H. a. anatolicum, while one group of calves (gr. 2) were immunized with cocktails of two antigens viz., surface antigens of T. annulata (rSPAG1, rTaSP). One group each was kept as negative controls (grs. 3 and 5). The animals of groups 1, 2 and 3 were challenged with T. annulata infected H. a. anatolicum adults while the animals of groups 1, 3, 4 and 5 were challenged with uninfected adult ticks. A significantly high (p<0.05) antibody responses to all the three antigens were detected in immunized calves, but the immune response was comparatively higher with rHaa86 followed by rTaSP and rSPAG1. Upon challenge with T. annulata infected ticks, animals of all groups showed symptoms of the disease but there was 50% survival of calves of group 1 while all non immunized control calves (group 3) and rSPAG1+rTaSP immunized calves died. The rHaa86 antigen was found efficacious to protect calves against more than 71.4-75.5% of the challenge infestation. The experiment has given a significant clue towards the development of rHaa86 based vaccine against both H. a. anatolicum and T. annulata.