Plasmodium falciparum gametocyte antibody responses and gametocytaemia

Little is known about the immune responses directed at circulating P. falciparum gametocytes in humans, knowledge of which would be useful in the development of intervention strategies to reduce and block malaria transmission. Consequently, antibody responses to surface antigens of P. falciparum gametocyte-infected-erythrocytes (GSA) were determined in plasma samples from asymptomatic Ghanaian school children between the ages of 6-17 years. These children were screened for malaria parasites and treated with dihydro-artemisinin piperaquine if positive, one week after first sample collection, and followed up weekly for one month. Gametocytes were produced from a laboratory adapted parasite line, 3D7a and a recent patient isolate from Kenya (HL1204). From a cohort of 113 children, all the children harboured plasma antibody responses that recognized GSA on a proportion of mature gametocyte-infected RBCs of 3D7a by flow cytometry. Children with strong anti-gametocyte antibodies were less likely to develop gametocytaemia over time. The significance of these results in relation to gametocyte carriage is discussed.