Malaria: Biology of the Merozoite-Erythrocyte Interface.

Studies were performed to investigate the use of pressure filtration as a means of isolation of free merozoites from an asynchronous sample of infected blood Plasmodium berghei. Although the procedure does yield large numbers of merozoites which appear intact using morphological criteria, the preparation also was found to contain large numbers of free trophozoites and a small but consistent number of intact parasitized and non-parasitized erythrocytes. If, by the use of multiple filtration steps, all contaminating red cells were removed from the preparations, the numbers of free parasites isolable which could invade normal mouse red cells in vitro was substantially reduced, if not totally abolished. Merozoite invasion in vitro has been found to be highly susceptible to small variations in medium pH, a finding which may be exploited in the future to studies to dissociate schizont rupturemerozoite release from merozoite invasion.