Effects of adjuvants on bovine humoral and cellular responses to hypodermin A

Hypodermin A, a serine protease of the first-instar larva of the common cattle grub, Hypoderma lineatum (Villers), when formulated with complete Freund's adjuvant and administered to naive calves, will elicit protective immunity defined by an increase in in vivo larval mortality. This study evaluated two veterinary acceptable adjuvants, alhydrogel and amphigen (alone and in combination), for suitability as an adjuvant for hypodermin A. Complete Freund's adjuvant (CFA) is not an acceptable adjuvant for use because of adverse reactions at the injection site. The veterinary acceptable adjuvants were not as effective as CFA in inducing an antibody response as detected in the peripheral circulation. Of the adjuvants evaluated, the mixture of alhydrogel and amphigen induced the highest serum antibody response to hypodermin A. All adjuvants evaluated induced comparable immediate-type skin test responses, and the mixture of alhydrogel and amphigen was most comparable with CFA in terms of delayed-type skin reaction and resultant cellular infiltration at the reaction site. Although the mixture of alhydrogel and amphigen, when compared with CFA, did not elicit comparable levels of responsiveness in all parameters tested, the overall performance of the mixture suggests it to be worthy of further efficacy investigation in a vaccine formulation with hypodermin A.