Development of sporozoite vaccines for malaria.

Various candidate sporozoite vaccines have been produced and tested. These have been produced by genetic engineering techniques and by polypeptide synthesis. The immunity produced by these synthetic vaccines is mediated by antibody and weak. The antibody levels achieved in human volunteer tests were similar to those resulting form natural infection. Immunity resulting from immunization with irradiated sporozoites is multifactorial. It includes reaction to malaria antigens on infected hepatocytes and it has cell-mediated components; the synthetic vaccines do not induce such reactions. Genetic restriction of cell-mediated immune responses may also limit the utility of synthetic vaccines. Development of an effective vaccine to prevent malaria will not be accomplished easily.