Antibody responses to Plasmodium falciparum gametocyte antigens during and after malaria attacks in schoolchildren from Madang, Papua New Guinea

Sera from 49 school children in Madang, Papua New Guinea with malaria and follow-up sera from 40 of these cases were tested by competitive ELISA for antibodies capable of inhibiting binding of eight monoclonal antibodies (MoAbs) to Plasmodium falciparum gametocytes. The proportion of sera inhibiting each MoAb ranged from 31.2% to 85.7%. At follow-up, the proportion of inhibitory sera decreased for 3 MoAbs, did not change significantly for 4 MoAbs and increased for one MoAb. When sera were grouped according to whether the follow-up blood slide was positive or negative, further trends emerged for MoAbs against the gamete surface antigen Pfs 48/45. Antibody levels to the IA3-B8 epitope decreased in follow-up positive cases, but remained unchanged for follow-up negative cases. The converse was observed for the IIC5-B10 epitope with an increase of antibody in follow-up positive cases and no change in the negative cases. Amount of antibody to the 3G12/58 epitope decreased when the follow-up was negative but not when it was positive. Increase in antibody to the 3E12/58 epitope occurred at the follow-up sample irrespective of the blood slide result. Thus four distinct patterns of longitudinal antibody response were observed against four epitopes on the same molecule.