Korean J Parasitol.  2015 Feb;53(1):43-49. 10.3347/kjp.2015.53.1.43.

Plasmodium vivax Drug Resistance Genes; Pvmdr1 and Pvcrt-o Polymorphisms in Relation to Chloroquine Sensitivity from a Malaria Endemic Area of Thailand

  • 1College of Public Health Sciences, Chulalongkorn University, Bangkok, Thailand.
  • 2Drug Discovery and Development Center, Thammasat University, Pathumthani, Thailand.
  • 3Center of Excellence in Molecular Biology and Pharmacology of Malaria and Cholangiocarcinoma, Chulabhorn International College of Medicine, Thammasat University, Patumthani, Thailand. kesaratmu@yahoo.com
  • 4Graduate Program in Biomedical Sciences, Allied Health Sciences, Thammasat University, Pathumthani, Thailand.


The aim of the study was to explore the possible molecular markers of chloroquine resistance in Plasmodium vivax isolates in Thailand. A total of 30 P. vivax isolates were collected from a malaria endemic area along the Thai-Myanmar border in Mae Sot district of Thailand. Dried blood spot samples were collected for analysis of Pvmdr1 and Pvcrt-o polymorphisms. Blood samples (100 mul) were collected by finger-prick for in vitro chloroquine susceptibility testing by schizont maturation inhibition assay. Based on the cut-off IC50 of 100 nM, 19 (63.3%) isolates were classified as chloroquine resistant P. vivax isolates. Seven non-synonymous mutations and 2 synonymous were identified in Pvmdr1 gene. Y976F and F1076L mutations were detected in 7 (23.3%) and 16 isolates (53.3%), respectively. Analysis of Pvcrt-o gene revealed that all isolates were wild-type. Our results suggest that chloroquine resistance gene is now spreading in this area. Monitoring of chloroquine resistant molecular markers provide a useful tool for future control of P. vivax malaria.


Plasmodium vivax; Pvmdr1; Pvcrt-o; drug resistance; chloroquine

MeSH Terms

Amino Acid Substitution
*Drug Resistance
Inhibitory Concentration 50
Malaria, Vivax/*parasitology
Membrane Transport Proteins/*genetics
Multidrug Resistance-Associated Proteins/*genetics
Mutation, Missense
Parasitic Sensitivity Tests
Plasmodium vivax/*drug effects/genetics
Protozoan Proteins/*genetics
Membrane Transport Proteins
Multidrug Resistance-Associated Proteins
Protozoan Proteins
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