In vitro cultivation of the exoerythrocytic stage of Plasmodium berghei in irradiated hepatoma cells.

Growth of cultures of human hepatoma cells was inhibited by exposure to doses of gamma irradiation as low as 1,000 rad., and the monolayers remained viable for up to 35 days. Irradiated cells were at least as susceptible to Plasmodium berghei sporozoite invasion as non-irradiated cells, and supported the entire exoerythrocytic cycle producing more infectious merozoites. Irradiated cultures may have use for culture of human malarias, and drug studies requiring synchronous cultures.