17 of 20 adult sera from the Amapa region of Brazil were active in the inhibition of P. falciparum sporozoite invasion (ISI) assay which has been correlated with protective antibodies. In contrast 11 sera were positive in IFA tests and 6 were positive in CSP tests. These results suggest that the ISI assay will be useful for evaluating naturally acquired protective anti-sporozoite antibodies in endemic areas, particularly during vaccine efficacy studies using sporozoite-based vaccines.
Anti-sporozoite antibody; inhibiton of sporozoite invasion (ISI) assay; circumsporozoite precipitation (CSP) assay; immunofluorescent antibody (IFA) assay