Differential recognition of Plasmodium falciparum merozoite surface protein 2 variants by antibodies from malaria patients in Brazil

Abstract

Four variants of merozoite surface protein 2 (MSP-2) of Plasmodium falciparum were used in serology to examine whether changes in repeat units affect its recognition by antibodies during infection with parasites of known MSP-2 types. The results indicate that variation in MSP-2 repeats may represent a mechanism for parasite immune evasion.

FIG. 1.

Schematic representation of MSP-2 of P. falciparum and the recombinant peptides used in this study. This protein is divided into five domains: conserved blocks (1 and 5) are represented as black boxes, and dimorphic, nonrepetitive blocks (2 and 4) are represented as either white or gray boxes. The central repetitive region (block 3) is shown as it occurs in the representative isolates FC27 and IC1, which define the dimorphic allelic families. FC27 and S20 peptides belong to the FC27 family but mostly differ in the sequence of block 3: FC27 has two copies of the 32-mer motif ADTIASGSQRSTNSASTSTTNNGESQTTTPTA followed by one copy of the 12-mer motif ESISPSPPITTT, whereas S20 has one copy of the 32-mer motif ADTVASGSQSSTNSASTSTTNNGESQTTTPTA followed by one copy of each of the 12-mer motifs ESNSPSPPITTT and KSNSPSPPITTT. The members of the IC1 family selected for this study, peptides FUP/CP and 3D7, share a common 4-mer motif, GGSA, which is repeated 12 times in FUP/CP and five times in 3D7.