Naturally acquired humoral and cellular immune responses to Plasmodium vivax merozoite surface protein 9 in Northwestern Amazon individuals

Antibody and T-cell reactivities to Plasmodium vivax merozoite Surface protein 9 (PvMSP9) were evaluated in a cross-sectional study of individuals naturally exposed to malaria infections living in Ribeirinha, a native riverine community and in Colina, a transmigrant community, Rondonia, Brazil. I-lie antibody responses to PvMSP9-RlRII and PvMSP9-Nt domains in Ribeirinha were higher compared with Colina and correlated with age and time of malaria exposure. IgG2 was most prevalent for PvMSP9-RII in both communities, and IgGl was the predominant isotype For PvMSP9-Nt and PvMSP9-RlRII in Ribeirinha. IFN-gamma and IL-4 predominated in Ribeirinha, while IFN-gamma predominated ill Colina. Variation ill exposure to 11 vivax likely accounts for the differences observed in cytokine and antibody levels between the two population Studied. (C) 2008 Elsevier Ltd. All rights reserved.