Immunization of cattle against Boophilus annulatus ticks using adult female tick antigen.

Ten crossbred calves (Friesian x Egyptian native) aged between 7-9 months old were used to evaluate the immunizing effect of whole adult B. annulatus tick antigen. A soluble fraction was obtained from extensively disrupted ticks and this fraction was used to vaccinate calves with 1 mg protein antigen. The vaccination protocol for five randomly selected calves involved two immunizations, the first was administered subcutaneously (plus aluminium hydroxide adjuvant) at the beginning of the experiment and the second was given 4 weeks later. At the same time, calves of the control group were injected with phosphate buffered saline (PBS) plus adjuvant. Ticks were counted on animals and the number of eggs laid per tick were counted and hatching percentages were determined. The vaccinated and control animals were skin tested with the antigen and calves were injected in three different sites with 50 microliters of 50, 100 and 200 ng of the antigen. At the same time, control sites were injected with PBS and the diameter of the immune response sites was measured using skin callipers. Immunization of calves showed that vaccination resulted in 73% reduction in the mean tick count. At the same time, immunization reduced the oviposition of ticks from vaccinated calves and the reduction percentage in egg laying was 65%. Vaccination induced a good immunity that could protect calves during the tick season (more than 5 months) as indicated from skin hypersensitivity reaction with the tick antigen.