Genetic polymorphism of Plasmodium falciparum msp-1, msp-2 and glurp vaccine candidate genes in pre-artemisinin era clinical isolates from Lakhimpur district in Assam, Northeast India

Abstract

Background. Northeast India shares its international border with Southeast Asia and has a number of malaria endemic zones. Monitoring genetic diversity of malaria parasites is important in this area as drug resistance and increasing genetic diversity form a vicious cycle in which one favours the development of the other. This retrospective study was done to evaluate the genetic diversity patterns in Plasmodium falciparum strains circulating in North Lakhimpur area of Assam in the pre-artemisinin era and compare the findings with current diversity patterns. Methods.Genomic DNA extraction was done from archived blood spot samples collected in 2006 from malaria-positive cases in Lakhimpur district of Assam, Northeast India. Three antigenic markers of genetic diversity were studied – msp-1 (block-2), msp-2 (block-3) and the glurp RII region of P. falciparum using nested PCR. Results. Allelic diversity was examined in 71 isolates and high polymorphism was observed. In msp-1, eight genotypes were detected; K1 (single allele), MAD20 (six different alleles) and RO33 (single allele) allelic families were noted. Among msp-2 genotypes, 22 distinct alleles were observed out of which FC27 had six alleles and IC/3D7 had 16 alleles. In RII region of glurp, nine genotypes were obtained. Expected heterozygosity (H E) values of the three antigenic markers were 0.72, 0.81 and 0.88, respectively. Multiplicity of infection (MOI) values noted were 1.28, 1.84 and 1.04 for msp-1, msp-2 and glurp, respectively. Conclusion. Results suggest a high level of genetic diversity in P. falciparum msp (block-2 of msp-1 and block-3 of msp-2) and the glurp RII region in Northeast India in the pre-artemisinin era when chloroqunine was the primary drug used for uncomplicated falciparum malaria. Comparison with current studies have revealed that the genetic diversity in these genes is still high in this region, complicating malaria vaccine research.

Comparative study of Plasmodium falciparum msp-1 and msp-2 Genetic Diversity in Isolates from Rural and Urban Areas in the South of Brazzaville, Republic of Congo

“…Allele sizes were determined with two molecular weight standards (100 bp DNA Ladder, New England Biolabs). Alleles were considered identical if the fragment sizes were within the range of 10 bp [ 15 ] and 20 bp [ 6 ] for msp-1 and msp-2 respectively.…”

Host-parasite interactions during Plasmodium infection: Implications for immunotherapies

“…A variety of MSPs and invasion complex proteins are responsible for erythrocyte invasion. It has been reported that msp1 and msp2 show high levels of genetic polymorphism which may complicate the malaria vaccine development ( 131 ). However, another study reported that MSP1 contains conserved B-cell epitopes indicating that MSP1 could serve as a promising vaccine candidate against P. vivax malaria ( 132 ).…”