IMMUNITY IN VACCINATED CATTLE EXPOSED TO EXPERIMENTAL AND NATURAL INFESTATIONS WITH BOOPHILUS-MICROPLUS

Gut membranes of the cattle tick Boophilus microplus were extracted us ing a low ionic strength buffer and the soluble antigens were used to vaccinate Hereford cattle. Following either experimental infestation w ith 40,000 larval ticks or exposure to field infestation, ticks from v accinated cattle laid 54 and 75% fewer eggs, respectively, than ticks from control cattle. After cattle were given booster injections of vac cine, and either experimentally infested with 20,000 larval ticks or e xposed to field infestation, the weight of eggs laid by ticks from vac cinated cattle was reduced by 80% and 52%, respectively. Acquired immu nity to the ticks varied considerably in both vaccinated and non-vacci nated cattle.