Analysis of naturally acquired antibody responses to the 19-kd C-terminal region of merozoite surface protein-1 of Plasmodium vivax from individuals in Sanliurfa, Turkey.

Plasmodium vivax is the second most prevalent global Plasmodium species causing malaria after P. falciparum. These two Plasmodium spp. co-exist in most endemic areas, apart from west and central Africa, which has only P. falciparum. However, southeastern Turkey is one of the exceptional regions with the sole presence of P. vivax infection, where a thorough epidemiologic survey has not been performed. Here, we report for the first time the identification of naturally acquired antibodies against the 19-kd C-terminal region of the merozoite surface protein-1 of P. vivax (PvMSP1(19)), using ELISA, from residents in the Sanliurfa region of southeastern Turkey. Among the 82 samples from patients with patent P. vivax malaria, 85% of the individuals were sero-reactive to PvMSP1(19). Particularly, 69.5% of the subjects were positive for IgM, 53.6% were positive for IgG (predominantly IgG1 and IgG3), and 7.3% were positive for IgA.