HUMORAL IMMUNE-RESPONSE TO THE ANTI-MALARIA VACCINE SPF66 IN THE COLOMBIAN ATRATO RIVER REGION

The immunogenicity of anti-malaria synthetic vaccine SPf66 was tested in a region of the Colombian middle Atrato river. The specific serum a ntibodies against SPf66 were quantified in vaccinees and placebo injec ted controls for a two-years period post-immunization. The frequency o f individuals showing seroconversion of anti-SPf66 antibodies three mo nths after completion of the immunization schedule was higher in vacci nees than in controls (52.7% and 25.5%, respectively, p < 0.01). Howev er; an over than four-fold increase of the specific anti-SPf66 antibod y titers was observed only in 1.4% of vaccinees and 0.2% of the contro ls (p < 0.01). The anti-Sgf66 antibody titers augmented in vaccinees f rom first dose application to three months after the third dose, conti nuously decreasing thereafter to reach below baseline values two years after completion of the immunization schedule. The results show that SPf66 has very low immunogenicity and induces a short term humoral imm une response (six months).