THE ORIGIN OF PARASITOPHOROUS VACUOLE MEMBRANE-LIPIDS IN MALARIA-INFECTED ERYTHROCYTES

During invasion of an erythrocyte by a malaria merozoite, an indentati on develops in the erythrocyte surface at the point of contact between the two cells. This indentation deepens as invasion progresses, until the merozoite is completely surrounded by a membrane known as the par asitophorous vacuole membrane (PVM). We incorporated fluorescent lipop hilic probes and phospholipid analogs into the erythrocyte membrane, a nd followed the fate of these probes during PVM formation with low-lig ht-level video fluorescence microscopy. The concentration of probe in the forming PVM was indistinguishable from the concentration of probe in the erythrocyte membrane, suggesting that the lipids of the PVM are continuous with and derived from the host cell membrane during invasi on. In contrast, fluorescently labeled erythrocyte surface proteins we re largely excluded from the forming PVM. These data are consistent wi th a model for PVM formation in which the merozoite induces a localize d invagination in the erythrocyte lipid bilayer, concomitant with a lo calized restructuring of the host cell cytoskeleton.