Differential antibody responses to Plasmodium falciparum merozoite proteins in Malawian children with severe malaria.

Cerebral malaria (CM) and severe malarial anemia (SMA) are 2 major causes of death in African children infected with Plasmodium falciparum. We investigated levels of naturally acquired antibody to conserved and variable regions of merozoite surface protein (MSP)-1 and MSP-2, apical membrane antigen (AMA)-1, and rhoptry-associated protein 1 in plasma samples from 126 children admitted to the hospital with CM, 59 with SMA, and 84 with uncomplicated malaria (UM) in Malawi. Children with SMA were distinguished by very low levels of immunoglobulin (Ig) G to the conserved C-terminus of MSP-1 and MSP-2 and to full-length AMA-1. Conversely, children with CM had significantly higher levels of IgG to the conserved regions of all antigens examined than did children with UM (for MSP-1 and AMA-1, P< .005; for MSP-2, P< .05) or SMA (for MSP-1 and MSP-2, P<.001; for AMA-1, P< .005). These distinct IgG patterns might reflect differences in age, exposure to P. falciparum, and/or genetic factors affecting immune responses.