Effect of placental malaria and HIV infection on the antibody responses to Plasmodium falciparum in infants.

BACKGROUND Placental malaria (PM) and maternal infection with human immunodeficiency virus (HIV) type 1 have been shown to affect infant morbidity and immune responses to Plasmodium falciparum. We studied the effects of PM and HIV infection on the antimalarial antibody responses and morbidity outcomes of infants throughout the first year of life. METHODS A total of 411 Kenyan infants who were born to mothers who were singly or dually infected with PM and/or HIV had their levels of immunoglobulin G antibody to 6 P. falciparum antigens/epitopes (apical membrane antigen-1, erythrocyte-binding antigen-175; liver-stage antigen-1 [LSA-1], circumsporozoite protein [CSP], merozoite surface protein-2, and rhoptry-associated protein-1 [RAP-1]) and to tetanus toxoid (TT) tested using enzyme-linked immunosorbent assay. RESULTS PM had little effect on the antibody responses of infants, whereas maternal HIV infection resulted in decreased levels of antibody to LSA-1, CSP, and RAP-1 epitopes at birth, compared with the absence of PM and maternal HIV infection (P = .0063). Levels of antibodies to TT were significantly reduced in infants born to mothers coinfected with HIV and PM, compared with the levels noted in infants born to HIV-negative mothers (P = .0003). In HIV-infected infants, levels of antibody to TT were reduced, but levels of antibody to malarial antigens were not. Antimalarial antibody levels were positively associated with malaria-related morbidity outcomes. CONCLUSION Infant HIV infection and maternal coinfection with HIV and PM negatively influence antibody responses to TT, but not those to malarial antigens, in infants. Antimalarial antibodies rarely showed protective associations with morbidity in infants and were more often a marker for malaria exposure and risk of infection.