ABSTRACT
In order to progress from the observation of protective immunity either in the irradiated sporozoite model or in naturally acquired immunity several tasks must be accomplished. First, the mechanism(s) of protection must be identificd. Second, the antigenic targets of that mechanism must be defined. Third, in vitro assays which measure the appropriate protective response and whieh can serve as surrogates for protective immunity during vaccine development must be developed. Fourth, vaccine delivery systems must be de veloped which are capable of stimulating particular, defined immune effector mechanisms and inducing protection. This review will examine the extent to which these tasks have been accomplished both for pre-erythrocytic vaccines broadly based on the irradiated sporozoite model and for erythrocytic and sexual stage vaccines based on naturally acquired immunity.
