Immunization of crossbred cattle (Bos indicus x Bos taurus) with fractionated midgut antigens against Hyalomma anatolicum anatolicum.

Crossbred calves (Bos indicus x Bos taurus) were immunized with a fractionated midgut supernate antigen (GS-F Ag from Hyalomma anatolicum anatolicum). The first inoculation on day 0 was given intramuscularly after emulsification with Freund's complete adjuvant; the second was given subcutaneously on day 14 in incomplete Freund's adjuvant; and the third on day 35 was given subcutaneously without adjuvant. Each injection comprised 1 mg of antigen protein. Ten days after the last inoculation, the immunized calves were challenged simultaneously with 1000 larvae and 20 pairs (20 males and 20 females) of adult H. a. anatolicum on one ear and a similar number of Hyalomma dromedarii ticks on the other ear. There was a significant decrease in the percentage larval engorgement and larval rejection of up to 34% on the immunized calves. A significant increase in the engorgement and preoviposition periods and a significant decrease in the engorged weight, egg mass weight and reproductive index were observed for adult female ticks when fed on the immunized calves. The GS-F Ag also induced a considerable degree of cross-protection in calves against H. dromedarii larval ticks.