In vitro culture of two populations (dividing and nondividing) of exoerythrocytic parasites of Plasmodium vivax.

Plasmodium vivax sporozoites invaded human hepatoma cells and differentiated into 2 types of exoerythrocytic (EE) parasites. One group was composed of actively dividing schizonts, which released merozoites after 9 days of culture. The second group was nondividing and persisted after the primary schizonts disappeared from the culture. EE schizonts progressively lost reactivity to monoclonal antibodies to the surface-protective protein antigen of P. vivax sporozoites, but the persisting parasites remained strongly reactive. In the 2 strains of P. vivax studied, the ratio of schizonts to persisting parasites was approximately equal.