Immunological studies on simian malaria III. Immunity to challenge and antigenic variation in P. knowlesi

Abstract

Immunity to reinfection in the simian malaria system studied was evidenced by (a) a delay in development of infections, (b) a milder course of parasitaemia, or (c) complete resistance to challenge. The immunity produced by repeated exposure to one antigenic variant was effective against subsequent challenge with heterologous variants. Populations of parasites isolated from different recrudescences of chronic P. knowlesi infections were shown to be antigenically distinct.