Low antibody responses to variant surface antigens of Plasmodium falciparum are associated with severe malaria and increased susceptibility to malaria attacks in Gabonese children.

We measured the levels of IgG antibodies with specificity for the variant surface antigens (VSA) of Plasmodium falciparum in plasma samples from a cohort of Gabonese children participating in a longitudinal case-control malaria study. Children with mild malaria had significantly higher anti-VSA IgG responses than their matched counterparts with severe malaria, most markedly during convalescence and when they were healthy. Over the course of the study, almost twice as many children who presented initially with mild rather than severe malaria developed antibodies recognizing the VSA expressed by each of a panel of three isolates, and those with the highest anti-VSA IgG responses had the lowest malaria attack rates. The results suggest that the clinical outcome of P. falciparum infection in young African children depends on their ability to both develop and maintain a broad profile of anti-VSA IgG antibodies, and that this ability is diminished in children who have experienced a severe malaria attack.