Antibodies against variable antigens expressed on the surface of Plasmodium falciparum-infected erythrocytes are believed
to be important for protection against malaria. A target for these antibodies is the P. falciparum erythrocyte membrane
protein 1, PfEMP1, which is encoded by around 50 var genes and undergoes clonal variation. Using agglutination and
mixed agglutination tests and flow cytometry to analyse the recognition of variant antigens on parasitized erythrocytes by
plasma antibodies from individuals living in Daraweesh in eastern Sudan, an area of seasonal and unstable malaria
transmission, we show that these antibodies recognize different variant antigens expressed by parasites of different
genotype. Comparing the levels and acquisition of antibody to variant antigens in pairs of parasite isolates expressing
different variant types, there is a correlation between the acquisition of antibodies to some combinations of variant antigens
but not to others. These results indicate that (1) a single infection will induce the production of antibodies recognizing
several variants of surface-expressed antigens, (2) the repertoire of variable antigens expressed by different parasites is
overlapping and the degree of overlap differs between isolates, and (3) the expression of at least some variant antigens is
genetically linked.