Longevity of naturally acquired antibody responses to the N- and C-terminal regions of Plasmodium vivax merozoite surface protein 1.
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.
Soares
I S
IS
Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, Brazil.
da Cunha
M G
MG
Silva
M N
MN
Souza
J M
JM
Del Portillo
H A
HA
Rodrigues
M M
MM
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
D000913:Antibodies, Protozoan; D000962:Antimalarials; D007074:Immunoglobulin G; D020066:Merozoite Surface Protein 1; D011994:Recombinant Proteins; D002738:Chloroquine; D011319:Primaquine