Genetic polymorphism of MSP2 and its implications for Plasmodium falciparum resistance in N’Djamena, Chad

Abstract

Background: Malaria control is a major challenge for countries in endemic areas, and Chad is one of them. The objective of this study was to determine the genetic diversity of the merozoite surface protein 2 (MSP-2) of Plasmodium falciparum in four health facilities in N’Djamena in order to better understand the variability of circulating strains and its epidemiological implications for malaria control. Methods: Blood samples were collected from 302 patients for both parasitological and molecular analyses. Positive samples were spotted on Whatman paper for molecular analyses. The parasite DNA was extracted by the chelex-100 method. The MSP2 gene was amplified by nested PCR and the revelation of this gene was done on a 1.3% agarose gel. The diversity parameters were calculated from the fragments and the number of alleles obtained. The data obtained were analyzed using SPSS 23 software. The phylogenetic tree of the Pf population was carried out using R software. Results: The prevalence of P. falciparum infection was 40.72% with a higher parasite intensity in women (317.81±109.93). Of the samples analyzed, 101 carried the MSP-2 gene (78.21%) on which 12 different alleles were obtained, thus a genetic diversity of 9.37%. A multiplicity of infections of 1.26 was determined with a percentage of 73.26; 25.74 and 1% respectively for monoclonal, double clonal and triple clonal infections. The phylogenetic tree showed 11 clades in four health structures of N’Djamena with parasites that are more or less genetically related. Conclusion: A significantly high genetic diversity thus indicates a high intensity of malaria transmission of P. falciparum. in N’Djamena. The multiplicity of infections and the high allelic diversity obtained allow us to understand that the malaria transmission situation in this area is critical and should guide studies of resistance to other antimalarial.