Comparison of Plasmodium falciparum allelic frequency distribution in different endemic settings by high-resolution genotyping

In the present study, a high-resolution capillary electrophoresis-based technique was applied to genotype samples from areas of different endemicity in Papua New Guinea and Tanzania. For both endemic settings, the diversity of msp1 and msp2 was investigated; the mean multiplicity of infection (MOI) and the FST values were determined to investigate whether more accurate sizing generates different results.The results of the present study confirmed previous reports of a higher mean MOI for both marker genes and increased genetic diversity in areas of higher endemicity as estimated by the total number of distinct alleles for msp2. For msp1 a minor increase in diversity was observed. Measures of between population variance in allele frequencies (FST) indicated little genetic differentiation for both marker genes between the two populations from different endemic settings. MOI adjusted for the probability of multiple infections sharing the same allele was estimated by using the msp2 allele frequency distribution and the distribution of observed numbers of concurrent infections. For the high-resolution typing technique applied in this study, this adjustment made little difference to the estimated mean MOI compared to the observed mean MOI.Plasmodium falciparum populations are highly diverse and individual hosts are often simultaneously infected by multiple parasite clones. In order to discriminate parasite clones within one host PCR-based genotyping of a number of different marker genes has been established. Among these are the merozoite surface proteins 1 and 2 (msp1 and msp2) and the glutamate-rich protein (glurp), which show extensive length polymorphism and can, therefore, be distinguished by electrophoresis on agarose or polyacrylamide gels.Recently, capillary electrophoresis (CE) based genotyping of msp2 was shown to have a much higher discriminatory power than previously applied techniques [1]. This technique has been proven useful in areas of high endemicity, where