Pvmdr1 Polymorphisms of Plasmodium vivax Isolates from Malaria Endemic Areas in Southern Provinces of Thailand

Abstract

Since chloroquine is the mainstay for treatment of Plasmodium vivax infection, monitoring of chloroquine drug resistance marker provides useful information for effective malaria control program.  The aim of the study was to investigate the genetic polymorphisms of pvmdr1 in Plasmodium vivax isolates collected from Southern Thailand. A total of 70 P. vivax isolates were collected by finger-prick from patients. DNA from dried blood spot samples were extracted and analyzed for pvmdr1 polymorphisms. Seven non-synonymous and one synonymous mutations were identified in pvmdr1 gene. Five haplotypes of pvmdr1 were observed with different frequencies. However, 21 isolates (30%) carried 4 mutations of 515R, 698S, 908L, and 958M. Amino acid Y976F and F1076L mutations, key point mutations associated with P. vivax chloroquine resistance, were detected in 17 (24.3%) and 38 (54.3%) isolates, respectively. The prevalence and pattern of mutations of pvmdr1 obtained from this study suggest the spreading of chloroquine resistance alleles in P. vivax isolates from Southern part of Thailand.  The monitoring of chloroquine drug resistance marker in P. vivax can provide useful information for early warning system and for developing the appropriate drug policy.