Lack of association between maternal antibody and protection of African infants from malaria infection

Maternally derived antibodies are believed to protect infants against infec tion, but there is little direct evidence for a protective role of passivel y acquired antibodies against malaria. A longitudinal study of malaria infe ction in 143 infants was conducted in a region of southern Ghana where Plas modium falciparum is endemic. Infants born in the high-transmission season were less likely to become infected in the first 20 weeks of life than chil dren born in the low-transmission season. Plasma, obtained at birth, was te sted for immunoglobulin G (IgG) and IgG subclasses to P. falciparum schizon ts and recombinant circumsporozoite antigen, MSP-1(19), MSP-2, AMA-I, and P f155 (also called ring-infected erytrocyte surface antigen). Antibody level s at birth were not associated with resistance to malaria infection. On the contrary, antibodies at birth were positively associated with infection, i ndicating that high levels of maternally derived antibodies represent a mar ker for intensity of exposure to malaria infection in infants, However, all five children who experienced high-density infections (>100 parasites/mu l of blood) were seronegative for MSP-1(19) at the time of infection.