Polymorphism of the Merozoite Surface Protein-1 Block 2 Region in Plasmodium Falciparum Isolates from Symptomatic Individual Living in Rural Area of Senegal

Background: Polymorphism and antigenic variation of malaria parasites determine malaria episode and its outcome. The aim of this study was to determine Plasmodium falciparum genetic diversity over time in population with uncomplicated malaria under ACT exposure in Senegal. Method: P. falciparum isolates collected from 300 individuals with uncomplicated malaria infection living in a rural area of Senegal from 2004 to 2008 were analyzed by a nested PCR amplification of msp1 and msp2 genes to compare P. falciparum allelic families’ diversity. Results: Allelic variation in both msp1 and msp2 genes were identified in the samples analyzed. For msp1 gene, 10 different alleles were found (3 msp1_K1, 4 msp1_Mad20 and 3 msp1_Ro33). Among them msp1_k1 allelic family was predominant (>70%) over year. Regarding msp2 gene, 7.0 different alleles were found (3 msp2_3D7, 4 msp2_FC27). However msp2_FC27 strain was predominant, especially in 2006 and 2007. Monoclonal infections were more frequent for msp1 gene, in 2004 (48.78%) and 2005 (45.05%) and for msp2 gene than polyclonal ones. Conclusion: This study demonstrated some differences in the P. falciparum diversity between symptomatic subjects over years living in rural area in Senegal and this should be taken into account when designing msp1 or msp2 malaria vaccine.