Plasmodium falciparumlacks sialidase and trans-sialidase activity

Abstract

SUMMARYSialic acid on the red cell surface plays a major role in invasion by the malaria parasitePlasmodium falciparum. The NeuAc(α2,3) Gal motif on theO-linked tetrasaccharides of the red cell glycophorins is a recognition site for the parasite erythrocyte-binding antigen (EBA-175). Consequently, the interaction ofP. falciparumand the red cell might share homology with that of the influenza virus. The cellular interactions ofP. falciparumwere examined for their sensitivity to 4-guanidino-2,3-didehydro-D-N-acetyl neuraminic acid (4-guanidino Neu5Ac2en), a potent inhibitor of influenza virus sialidase. Parasite invasion and subsequent development was unaffected by the sialidase inhibitor. The inhibitor did not affect rosette formation of parasite-infected erythrocytes with uninfected cells nor their cytoadherence to C32 melanoma cells. Furthermore, we were unable to confirm the presence of a previously reported parasite sialidase using sensitive fluorometric or haemagglutination assays, neither was any malarial trans-sialidase identified. We conclude thatP. falciparumpossesses neither sialidase nor trans-sialidase activity and that an inhibitor of influenza virus sialidase has no effect on important cellular interactions of this parasite.