Fig. 6

AMA1-specific growth inhibition in low and high AMA1 antibody responders determined by ELISA. a Prevalence of specific growth inhibition of genetically engineered P. falciparum expressing different AMA1 alleles (>10 % inhibition of one line compared with either of two other lines tested simultaneously), according to level of antibody response to specific AMA1 alleles determined by ELISA (high responses classified as greater than the median value) (n = 99). Prevalence of specific inhibition for HB3 and XIE was too low to be included in the analysis. Error bars indicate standard error. There was a significant difference in the prevalence of FVO-specific and W2mef-specific inhibitory antibodies between low and high responders by ELISA (P < 0.05, Fisher’s exact test). b Allele-specific antibodies to FVO and 3D7 AMA1 were measured by competition ELISA in selected serum samples that showed FVO-specific growth inhibition (growth of genetically engineered P. falciparum expressing FVO at least 10 % lower than growth of genetically engineered P. falciparum expressing 3D7 AMA1 (n = 24)), and amongst samples with no differential growth inhibition (n = 64). Higher levels of FVO allele-specific antibodies (FVO AMA1-specific antibodies that do not cross-react with 3D7 AMA) than 3D7 allele-specific antibodies (3D7 AMA1-specific antibodies that do not cross-react with FVO AMA1) were observed amongst samples with FVO-specific growth inhibition (Mann-Whitney U test, P < 0.0001)