Recent advances in applied malaria immunology

Our present knowledge of cellular and humoral factors which are involved in immunity to plasmodial infections are discussed. Immunization against plasmodial infection has been achieved in birds, rodents, simians, and humans. Avian hosts have been immunized against gametocytes which resulted in inhibition of gametocytes within the mosquito vector. Immunization of humans against plasmodial gametocytes would indirectly protect them against malaria by blocking mosquito transmission to other susceptible individuals. Immunization by sporozoites provides short-lived protection against sporozoite challenge, but gives no protection against erythrocytic forms. Some success has been obtained in immunizing avian and mammalian hosts with exoerythrocytic forms obtained from cultured avian cells. The most significant advances have occurred in immunizing simian hosts against simian or human malaria by vaccinating with fresh erythrocytic merozoites or a nonviable lyophilized antigen obtained from intraerythrocytic forms. The development of an antigen preparation suitable for use as a human malaria vaccine is dependent upon prior development of an in vitro system which would provide adequate amounts of parasite material. Efforts to cultivate the sporogonic, exoerythrocytic, and erythrocytic, and erythrocytic phases of plasmodia as well as the feasibility of using these forms for vaccination are discussed.