Protein-Based Vaccine May Protect Against Malaria

In Brazil, Plasmodium vivax was responsible for 80% of the 600,000 cases of malaria reported in 2005 and malaria-related morbidity across the Amazon Basin. Emerging resistance to the frontline antimalarial drug, chloroquine, is of major concern as the mutation of target antigens complicates the development of new preventative therapies.

PvMSP-1, a protein of P. vivax is a target of naturally acquired and vaccine-induced immunity to malaria, however it can occur in up to six different forms. In the study researchers studied noninfected subjects exposed to malaria in rural Amazonia for antibody responses to proteins corresponding to PvMSP-1 commonly found in local parasites. Initially, less than one third had detectable antibodies, however antibody response increased dramatically following acute P. vivax infection.

"We suggest that antibody responses to the repertoire of variable domains of PvMsP-1 to which subjects are continuously exposed are elicited only after several repeated infections and may require frequent boosting, with clear implications for the development of PvMSP-1-based subunit vaccines," say the researchers.

They report their findings in the October 2007 issue of the journal Clinical and Vaccine Immunology.

Article: M.S. Bastos, M. da Silva-Nunes, R.S. Malafronte, E. Hellena, E. Hoffmann, G. Wunderlich, S.L. Moraes, M.U. Ferreira. 2007. Antigenic polymorphism and naturally acquired antibodies to Plasmodium vivax merozoite surface protein 1 in rural Amazonians. Clinical and Vaccine Immunology, 14. 10:1249-1259.