Lack of sequence diversity in the gene encoding merozoite surface protein 5 of Plasmodium falciparum

The gene encoding merozoite surface protein 5 (MSP5) of Plasmodium falcipar um is situated between the genes encoding MSP2 and MSP4 on chromosome 2. Bo th MSP4 and MSP5 encode proteins that contain hydrophobic signal and glycos ylphosphatidylinositol (GPI) attachment signals and a single epidermal grow th factor (EGF)-like domain at their carboxyl termini. The similar gene org anization, location and similar structural features of the two genes sugges t that they have arisen from a gene duplication event. In this study we pro vide further evidence for the merozoite surface location of MSP5 by demonst rating that MSP5 is present in isolated merozoites, partitions in the deter gent-enriched phase following Triton X-114 fractionation and shows a staini ng pattern consistent with merozoite surface location by indirect immunoflu orescence confocal microscopy. Analysis of antigenic diversity of MSP5 show s a lack of sequence variation between various isolates of P. falciparum fr om different geographical locations, a feature unusual for surface proteins of merozoites and one that may simplify vaccine formulation. (C) 1999 Else vier Science B.V. All rights reserved.