Approaches to studying genetic diversity of Plasmodium falciparum using a DNA sequence variation

Sequence variation in the calmodulin and thrombospondin related anonymous protein (TRAP) genes has been examined following amplification using the polymerase chain reaction (PCR). The intron of the calmodulin gene has four repeating motifs which vary in length: three of these contain a dinucleotide repeat, dA-dT, while the fourth is a pentameric repeating unit dA-dT-dA-dT-dT. These DNA polymorphisms can be applied to the study of parasite populations in mixed infections and in strain identification. The known sequence diversity in the TRAP gene has been converted to an RFLP analysis following PCR amplification. Comparisons between the chemical cleavage method and the direct sequencing of PCR amplified products of the TRAP gene, suggest that the latter method is preferable when analysing sequences as variant as TRAP.