Immunization of cattle (Bos indicus X Bos taurus) against Hyalomma anatolicum anatolicum using antigens derived from tick salivary gland extracts.

Studies were conducted on 41 cross-bred (Bos taurus x Bos indicus) calves which were less than 1 year old. Three types of salivary gland antigens (SG Ag) viz. SG Ag-I (whole), SG Ag-II (supernatant) and SG Ag-III (sediment), prepared from the ixodid tick, Hyalomma anatolicum anatolicum, were used for immunizing these calves. The calves were divided into five groups. The first three groups were immunized with SG Ag-I, -II and -III with Freund's complete adjuvant (FCA), respectively. The fourth group was immunized with SG Ag-I (without adjuvant), and the fifth group remained as an unimmunized control inoculated with FCA only. In all the groups, immunization was carried out on days 1 and 14 and the animals were challenged on the 21st day. Significant resistance developed in the calves of the SG Ag-I and SG Ag-II (both with FCA) groups. Of all, SG Ag-I with FCA proved the most potent immunogen. Both humoral and cellular immune responses were demonstrated by in vivo and in vitro tests. The capillary tube agglutination test and double diffusion test gave positive reactions 21 days after first immunization. The immunized calves showed a significant increase in the levels of serum gamma globulin and per cent 'E' rosettes. Tick salivary gland antigens therefore seem to have promising potentials in inducing resistance in calves.