title: Acquired immune responses to the N- and C-terminal regions of Plasmodium vivax merozoite surface protein 1 in individuals exposed to malaria.
abstract: In this study, we evaluated the naturally acquired immune response to Plasmodium vivax merozoite surface protein 1 (PvMSP1) in individuals with recent clinical episodes of malaria from the state of Para, Brazil. Ten recombinant proteins representing the first 682 amino acids (aa) of the N-terminal region and one representing the final 111 aa of the C-terminal region were expressed in Escherichia coli as glutathione S-transferase fusion proteins. Both of these regions have been suggested as candidates for development of a vaccine against Plasmodium sp. The total frequencies of individuals with antibodies and cellular immune responses to PvMSP1 were high (83.8 and 75%, respectively). The recombinant proteins representing the N- and C-terminal regions were recognized by 51.4 and 64.1% of sera, respectively. The frequency of responders to the C-terminal region increased according to the number of previous malaria episodes, reaching 83.3% after four episodes. Cellular immune response was measured by in vitro proliferation and gamma interferon production. Peripheral blood mononuclear cells of 75 and 47.2% of individuals proliferated in response to stimulation by the N- and C-terminal regions, respectively. Also, we found that one protein representing the N terminus and a second representing the C terminus of PvMSP1 stimulated 54.5% of individuals to secrete gamma interferon. We concluded that PvMSP1 is immunogenic to a large proportion of individuals exposed to malaria. Our results also suggested that the C-terminal region of PvMSP1 containing the two epidermal growth factor-like domains is particularly immunogenic to antibodies and T cells during natural infection in humans.
authors.affiliation: Departamento de Patologia, Centro de Ciências Biológicas, Universidade Federal do Pará, Brazil.
authors.forename: I S
authors.initials: IS
authors.lastname: Soares
authors.forename: G
authors.initials: G
authors.lastname: Levitus
authors.forename: J M
authors.initials: JM
authors.lastname: Souza
authors.forename: H A
authors.initials: HA
authors.lastname: Del Portillo
authors.forename: M M
authors.initials: MM
authors.lastname: Rodrigues
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D000913:Antibodies, Protozoan / Q000032:analysis* / Q000097:blood; D001938:Brazil / Q000453:epidemiology; D002455:Cell Division; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000235:genetics; D005260:Female; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D007111:Immunity, Cellular; D007074:Immunoglobulin G / Q000032:analysis / Q000276:immunology; D007371:Interferon-gamma / Q000096:biosynthesis; D007963:Leukocytes, Mononuclear / Q000166:cytology; D016780:Malaria, Vivax / Q000097:blood / Q000453:epidemiology / Q000276:immunology*; D008297:Male; D020066:Merozoite Surface Protein 1; D008875:Middle Aged; D010966:Plasmodium vivax / Q000235:genetics / Q000276:immunology*; D011498:Protein Precursors / Q000235:genetics / Q000276:immunology*; D015800:Protozoan Proteins / Q000235:genetics / Q000276:immunology*; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D011995:Recombination, Genetic; D016036:Seroepidemiologic Studies; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology
chemical_list: D000913:Antibodies, Protozoan; D007074:Immunoglobulin G; D020066:Merozoite Surface Protein 1; D011498:Protein Precursors; D015800:Protozoan Proteins; D011994:Recombinant Proteins; D007371:Interferon-gamma