Members of the merozoite surface protein 7 family with similar expression patterns differ in ability to protect against Plasmodium yoelii malaria.
Previously, we described the isolation of the Plasmodium yoelii sequence-related molecules P. yoelii MSP-7 (merozoite surface protein 7) and P. yoelii MSRP-2 (MSP-7-related protein 2) by their ability to interact with the amino-terminal end of P. yoelii MSP-1 in a yeast two-hybrid system. One of these molecules was the homologue of Plasmodium falciparum MSP-7, which was biochemically isolated as part of the shed MSP-1 complex. In the present study, with antibodies directed against recombinant proteins, immunoprecipitation analyses of the rodent system demonstrated that both P. yoelii MSP-7 and P. yoelii MSRP-2 could be isolated from parasite lysates and from parasite culture supernatants. Immunofluorescence studies colocalized P. yoelii MSP-7 and P. yoelii MSRP-2 with the amino-terminal portion of MSP-1 and with each other on the surface of schizonts. Immunization with P. yoelii MSRP-2 but not P. yoelii MSP-7 protected mice against a lethal infection with P. yoelii strain 17XL. These results establish that both P. yoelii MSP-7 and P. yoelii MSRP-2 are expressed on the surface of merozoites and released from the parasite and that P. yoelii MSRP-2 may be the target of a protective immune response.
Mello
Kerrianne
K
Division of Molecular Parasitology, Department of Microbiology & Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129, USA.
Daly
Thomas M
TM
Long
Carole A
CA
Burns
James M
JM
Bergman
Lawrence W
LW
D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay; D007114:Immunization; D008288:Malaria / Q000517:prevention & control*; D017780:Malaria Vaccines / Q000276:immunology*; D008297:Male; D008565:Membrane Proteins / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D010967:Plasmodium yoelii / Q000276:immunology*; D011233:Precipitin Tests; D015800:Protozoan Proteins / Q000276:immunology*
D000913:Antibodies, Protozoan; D017780:Malaria Vaccines; D008565:Membrane Proteins; D015800:Protozoan Proteins; C439571:merozoite surface protein 7, Plasmodium