title: Plasmodium falciparum lacks sialidase and trans-sialidase activity.
abstract: Sialic acid on the red cell surface plays a major role in invasion by the malaria parasite Plasmodium falciparum. The NeuAc(alpha 2,3) Gal motif on the O-linked tetrasaccharides of the red cell glycophorins is a recognition site for the parasite erythrocyte-binding antigen (EBA-175). Consequently, the interaction of P. falciparum and the red cell might share homology with that of the influenza virus. The cellular interactions of P. falciparum were 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 that P. falciparum possesses neither sialidase nor trans-sialidase activity and that an inhibitor of influenza virus sialidase has no effect on important cellular interactions of this parasite.
authors.affiliation: Department of Infection and Tropical Medicine, Imperial College School of Medicine, Northwick Park Hospital, Middlesex, UK.
authors.forename: B
authors.initials: B
authors.lastname: Clough
authors.forename: F A
authors.initials: FA
authors.lastname: Atilola
authors.forename: N
authors.initials: N
authors.lastname: Healy
authors.forename: M E
authors.initials: ME
authors.lastname: Pereira
authors.forename: R C
authors.initials: RC
authors.lastname: Bethell
authors.forename: C R
authors.initials: CR
authors.lastname: Penn
authors.forename: G
authors.initials: G
authors.lastname: Pasvol
mesh_terms: D000818:Animals; D002448:Cell Adhesion; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004912:Erythrocytes / Q000469:parasitology; D006146:Guanidines; D006801:Humans; D009439:Neuraminidase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009975:Orthomyxoviridae / Q000201:enzymology; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000254:growth & development / Q000472:pathogenicity*; D011714:Pyrans; D012397:Rosette Formation; D012794:Sialic Acids / Q000494:pharmacology; D053243:Zanamivir
chemical_list: D004791:Enzyme Inhibitors; D006146:Guanidines; D011714:Pyrans; D012794:Sialic Acids; D009439:Neuraminidase; D053243:Zanamivir