Merozoite surface protein-3α is a reliable marker for population genetic analysis of Plasmodium vivax

Background: The knowledge on population structure of the parasite isolates has contributed greatly to understanding the dynamics of the disease transmission for designing and evaluating malaria vaccines as well as for drug applications. msp-1 and msp-3 a genes have been used as a genetic marker in population studies of Plasmodium vivax isolates. In this study, msp-3 a was compared and assessed with msp-1 marker in order to find whether msp-3 a is a reliable genetic marker for P. vivax population studies. Methods: This comparative study was designed and carried out as the first assessment of diversity in Pvmsp-3 a gene by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in the 50 northern and 94 southern P. vivax isolates from Iran, which had been analysed before for msp-1 gene. Results: Three allele size as, Type A (1.8 kb), Type B (1.5 kb) and Type C (1.2 kb) have been detected among both northern and southern isolates based on PCR results. Type C (70%) and Type A (68.7%) were the predominant fragments among northern and southern parasites, respectively. 99 distinct Pvmsp-3 alpha fragments defined by the size were detected in the 94 southern samples by PCR analysis. However, no mixed genotype infections have been detected among northern isolates. Based on restriction pattern from digestion with Hha I and Alu I 12 and 49 distinct allelic variants have been detected among 50 northern and 94 southern isolates. However, based on msp-1 gene, 30 distinct variants identified in all 146-sequenced Iranian P. vivax isolate. Conclusion: The results suggested that PCR-RFLP on msp-3 a gene is an adequate, applicable and easily used technique for molecular epidemiology studies of P. vivax isolates without the need for further sequencing analysis.