Genetic structure of Plasmodium vivax and Plasmodium falciparum in the Bannu district of Pakistan

Abstract

BackgroundPlasmodium vivax and Plasmodium falciparum are the major causative agents of malaria. While knowledge of the genetic structure of malaria parasites is useful for understanding the evolution of parasite virulence, designing anti-malarial vaccines and assessing the impact of malaria control measures, there is a paucity of information on genetic diversity of these two malaria parasites in Pakistan. This study sought to shed some light on the genetic structure of P. vivax and P. falciparum in this understudied region.MethodsThe genetic diversities of P. vivax and P. falciparum populations from the densely populated, malaria-endemic Bannu district of Pakistan were evaluated by analysis of their merozoite surface protein (msp) genes by PCR-RFLP. Specifically, the Pvmsp-3α and Pvmsp-3β genes of P. vivax and the Pfmsp-1 and Pfmsp-2 genes of P. falciparum were analysed.ResultsIn P. vivax, genotyping of Pvmsp-3α and Pvmsp-3β genes showed a high level of diversity at these loci. Four distinct allele groups: A (1.9 kb), B (1.5 kb), C (1.2 kb), and D (0.3 kb) were detected for Pvmsp-3α, type A being the most prevalent (82%). Conversely, amplification of the P. vivax msp-3β locus produced two allele groups: A (1.7-2.2 kb, 62%) and B (1.4-1.5 kb, 33%), with 5% mixed-strain infections. Restriction analysis of Pvmsp-3α and Pvmsp-3β yielded 12 and 8 distinct alleles, respectively, with a combined mixed genotype prevalence of 20%. In P. falciparum, all three known genotypes of Pfmsp-1 and two of Pfmsp-2 were observed, with MAD20 occurring in 67% and 3D7/IC in 65% of the isolates, respectively. Overall, 24% P. falciparum samples exhibited mixed-strain infections.ConclusionThese results indicate that both P. vivax and P. falciparum populations in Pakistan are highly diverse.

Genetic diversity in human malarial parasites of Khyber Agency Pakistan

“…In our study the average parasite density was 2050 parasites/μl which are comparable with the study observed from Punjab, Pakistan (Pryblski et al 1999) and Thailand (O'maera et al 2006) though quite less as compared to 10,000 parasites/μl was observed in Africa (Rogier et al 1996). Msp-3α was found to have two alleles A and B of which B was more prevalent and polymorphic contradicting previous studies from Iran (Zakeri et al 2006a, b), India and Pakistan (Khatoon et al 2010) where three alleles were observed with type A being the most prevalent. The pvmsp-3β gene resulted in amplification of two major alleles of which 15% of type B remains uncut which mirrors previous findings from Pakistan [Khayber Pakhtoonkhaw] (Khatoon et al 2010 and2012) but contradicting observations from China and Thailand (Yang et al 2006).…”

“…Msp-3α was found to have two alleles A and B of which B was more prevalent and polymorphic contradicting previous studies from Iran (Zakeri et al 2006a, b), India and Pakistan (Khatoon et al 2010) where three alleles were observed with type A being the most prevalent. The pvmsp-3β gene resulted in amplification of two major alleles of which 15% of type B remains uncut which mirrors previous findings from Pakistan [Khayber Pakhtoonkhaw] (Khatoon et al 2010 and2012) but contradicting observations from China and Thailand (Yang et al 2006). P. falciparum msp-1 and msp-2 candidates for malaria vaccine development (Moorthy and Hill 2002) have been found to have 11 genotypes for former and 16 for later, which is comparable to 10 and 17 alleles of Thailand (Snounou et al 1999) respectively but somewhat less diverse than 25 alleles of msp-1 and 19 alleles of msp-2 of West Uganda as described by Aubuoy (Aubouy et al (2003).…”

“…Allelic diversity at the P. vivax merozoite surface protein-3a (pvmsp-3a) locus was investigated using a combined polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) protocol described by Khatoon et al 2010. In Nest 1 reaction one pair of oligonucleotide primer pair P1 (5'-CAGCAGACACCATTTAAGG-3') and P2 (5'-CCGTTTGTTGATTAGTTGC-3') was used for amplification of pvmsp-3α gene.…”

“…They observed 25 genotypes msp-1 (12 KI; 8 MAD20; 5 RO33) and 33 for msp-2 (14 FC27; 19 3D7/IC) among 238 studied isolates (Ghanchi et al 2010). From Bannu, Pakistan, all three known genotypes of Pfmsp-1 and two of Pfmsp-2 were observed, with MAD20 occurring in 67% and 3D7/IC in 65% of the isolates, respectively while, 24% of the isolates exhibited mixed-strain infections (Khatoon et al 2010). From Kohat, Pakistan P. falciparum showed that K1+MAD20 mixed genotype was dominant in msp-1 and FC27 in msp-2 (Khatoon et al 2012).…”

“…Conversely, amplification of the P. vivax msp-3β locus produced two allele groups: A (1.7-2.2 kb, 62%) and B (1.4-1.5 kb, 33%), with 5% mixed-strain infections (Khatoon et al 2010). Out of 130 studied isolates from Kohat region of Khyber Pakhtoonkhwa (KPK) 37 Type A, 4 Type B, *Corresponding author: lukh@sund.ku.dk Diversity in human malaria parasites of Pakistan 565 9 Type C, 2 Type D (0.75 kb) and 2 mixed genotypes were investigated using PCR amplification (Khatoon et al 2012).…”