[Genotypic survey of Plasmodium falciparum based on the msp1, msp2 and glurp genes by multiplex PCR]

Abstract

Introduction: The genetic diversity of Plasmodium falciparum has been one of the major obstacles for the success of anti-malaria drug therapy. It provides the parasite an ability to evade the host's immune response by generating changes in its antigenic composition and resistance to antimalarial drugs.

Objective: The genetic diversity of P.falciparum was characterized in 4 Colombian localities through the analysis of polymorphic genes.

Materials and methods: Eighty-one samples were obtained from patients with uncomplicated P. falciparum malaria and screened for polymorphic variants of msp1, msp2 (merozoite surface proteins) and glurp (glutamate-rich protein) with a multiplex PCR assay. The geographic regions sampled were Tierralta (Córdoba), in northwestern Colombia and in the Orinoco river watershed of eastern Colombia--Inírida (Guainía), La Carpa (Guaviare), and Casuarito (Vichada).

Results: The MAD20 variant was detected in all samples analyzed for the msp1 gene. For the msp2 gene, the IC allelic family was found in 96.3% of the samples as compared to 4.9% of the samples with the FC family. Both families showed size polymorphism with bands between 467 and 513 basepairs (bp) for IC and 286 and 300 bp for FC. PCR products of differing sizes were detected for the glurp gene and grouped into 5 size classes: I (600-699 bp) 2.5%, II (700-799 bp) 19.8%, III (800-899 bp) 72.8%, IV (900-999 bp) 1.2% and V (1000-1099 bp) 3.7%.

Conclusions: The msp1 molecular marker did not provide information for differentiating P. falciparum parasite populations. The msp2 gene was more suitable for studying the genetic diversity, however, further studies are required to identify polymorphisms within the two allelic families. The glurp gene showed a great genetic diversity of circulating P. falciparum populations, and suggested that this gene may be useful for distinguishing between recrudescence and reinfection.