A 46,000 dalton Plasmodium falciparum merozoite surface glycoprotein not related to the 185,000-195,000 dalton schizont precursor molecule: isolation and characterization.

A 46,000 dalton glycoprotein was isolated by extraction of freshly harvested P. falciparum merozoites (FCB1 strain), followed by gel electrophoresis of the extract and electroelution. The antigen is present in the late ring, trophozoite, schizont, and segmenter stages and is localized on the merozoite surface at the end of schizogony.

Isolation and characterization of the 80,000 dalton Plasmodium falciparum merozoite surface antigen.

The 80,000 dalton merozoite surface protein, derived from the 185,000-195,000 dalton schizont precursor, was isolated from detergent extracts of naturally-released merozoites using chromatographic procedures. A rabbit antiserum raised against this antigen was used for characterizing the 80,000 dalton fragment. The antiserum did not inhibit merozoite invasion or parasite growth in vitro, suggesting that this merozoite surface antigen is not directly involved in the invasion process of the merozoite into the host erythrocyte.

Spontaneously released Plasmodium falciparum merozoites from culture possess glycoproteins.

Using metabolic labeling techniques with either radioactive glucosamine or various sugars in synchronous Plasmodium falciparum cultures it was proven that merozoites isolated from such cultures possess glycoproteins. Biosynthesis and processing of these glycoproteins were investigated.

Identification of surface and internal antigens from spontaneously released Plasmodium falciparum merozoites by radio-iodination and metabolic labelling.

Spontaneously released merozoites from synchronous Plasmodium falciparum cultures were isolated in the presence of protease blocker. 1-5 X 10(10) merozoites were obtained in each experiment. The isolated merozoites possessed a thick surface coat and about 80% were invasive to human erythrocytes although they did not subsequently develop into ring stages.