Plasmodium falciparum: variations within the C-terminal region of merozoite surface antigen-1.

Sequence variations at the 3'-end of the Plasmodium falciparum merozoite surface antigen-1 gene show that the C-terminus of the protein may not be as conserved as has been assumed in the past. We have therefore examined the sequences of the 3' terminal 2 kb, i.e., blocks 12-17 of four isolates, RO-33, RO-71, 3D7A, and FCH5. We discuss different mechanisms of genetic exchange that could account for the observed variations. Furthermore the deduced amino acid sequences allow us to identify allelic epitopes of three monoclonal antibodies. Finally, our data complete the sequence of two additional independent alleles of this gene (RO-33 and RO-71).