TICK INFESTATIONS ON CATTLE VACCINATED WITH EXTRACTS FROM THE EGGS AND THE GUT OF BOOPHILUS-MICROPLUS

Extracts prepared from the membranes of eggs (EM) and guts (GM) of Boophilus microplus were used to immunise cattle which were then infested twice with 20 000 larval ticks 1 week apart. EM antigens did not protect cattle against challenge with ticks, despite high levels of anti-egg antibodies in the sera of the vaccinated cattle, detected by an indirect enzyme-linked immunosorbent assay (ELISA). Cattle vaccinated with GM, however, had high levels of antibodies against GM and were protected significantly against challenge with B. microplus. Anti-EM and anti-GM antibodies in the sera of cattle cross-reacted significantly with GM and EM respectively on ELISA and recognised both specific and common antigens in extracts of the eggs and guts of B. microplus on Western blots. Exposure of cattle to field infestation with ticks during vaccination with gut antigens did not adversely affect the levels of antibodies generated.