title: Longevity of naturally acquired antibody responses to the N- and C-terminal regions of Plasmodium vivax merozoite surface protein 1.
abstract: In an earlier study, we found that individuals with patent infection had significantly higher IgG antibody titers to the 19-kD C-terminal region of Plasmodium vivax merozoite surface protein 1 (PvMSP1) than individuals treated for malaria 1-4 months earlier. These results suggested that the antibody levels decreased rapidly following treatment. The present study was designed to determine the persistence of antibody response to the N- and C-terminal regions of PvMSP1 after infection with P. vivax in individuals from the city of Bélem in northern Brazil. Our results demonstrated that the vast majority of individuals had a significant decrease in antibody titers to the C-terminal region of PvMSP1 in a period of two months following treatment. Among responders to the C-terminal region, 44.4% became serologically negative and 44.4% had their antibody titers reduced by an average of 13-fold. Only 11.2% of the individuals had their antibody titers maintained or slightly increased during that period. A decrease in the antibody response to the recombinant protein representing the N-terminal region of PvMSP1 was also noted; however, it was not as dramatic. The rapid decrease in the antibody levels to the C-terminal region of PvMSP1 might contribute to the high risk of reinfection in these individuals.
authors.affiliation: Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, Brazil.
authors.forename: I S
authors.initials: IS
authors.lastname: Soares
authors.forename: M G
authors.initials: MG
authors.lastname: da Cunha
authors.forename: M N
authors.initials: MN
authors.lastname: Silva
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: D000328:Adult; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood* / Q000276:immunology; D000962:Antimalarials / Q000627:therapeutic use; D001938:Brazil / Q000453:epidemiology; D002738:Chloroquine / Q000627:therapeutic use; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D016780:Malaria, Vivax / Q000188:drug therapy / Q000453:epidemiology / Q000276:immunology*; D008297:Male; D020066:Merozoite Surface Protein 1 / Q000276:immunology*; D010966:Plasmodium vivax / Q000276:immunology*; D011319:Primaquine / Q000627:therapeutic use; D011994:Recombinant Proteins / Q000276:immunology; D012008:Recurrence; D013997:Time Factors
chemical_list: D000913:Antibodies, Protozoan; D000962:Antimalarials; D007074:Immunoglobulin G; D020066:Merozoite Surface Protein 1; D011994:Recombinant Proteins; D002738:Chloroquine; D011319:Primaquine