Geographic diversity of Plasmodium falciparum antibodies in Madagascar

Plasma samples from 50 subjects living in three distinct regions in Madagascar (Ankazobe, Manakara, and Foulpointe) were studied by sodium dodecyl sulphate polyacrylamide gel electrophoresis of immunoprecipitated proteins from a Plasmodium falciparum strain (FCM22/Madagascar) which had been biosynthetically labelled with 35S-methionine and maintained in long-term in-vitro culture. Four major proteins with molecular weights of 96, 100, 110, and 118 kD were precipitated by plasma from Ankazobe, whereas low molecular weight proteins (27, 40, and 47 kD) were recognised more often by plasma from Foulpointe. Plasma from Manakara immunoprecipitated proteins of intermediate molecular weight. Variations in the immunological response according to the area, or antigenic diversity among the parasitic isolates might account for these results.