Age-dependent occurrence of protective anti-Plasmodium falciparum sporozoite antibodies in a holoendemic area of Liberia

Antibodies to Plasmodium falciparum sporozoites were detected in children aged 6 months to 9 years, and in adults, in a holoendemic village near Yekepa, Liberia, by-enzyme linked immunosorbent assay (ELISA) usina the recombinant circumswrozoite protein ‘R32tet & or by inhibition of sporozoite inva-sion (ISI) of hepatoma cells. Both assays were significantly correlated with each other and showed that anti-sporozoite antibodies increase with age. IS1 was more sensitive than ELISA and demonstrated significantly increased anti-sporozoite antibodies at age 5-6 years, when young children show partial clinical resistance to malaria. These results suggest that anti-sporozoite antibodies, as measured by ISI, may contribute to protection against malaria