Molecular Characterization of Dihydrofolate Reductase-Thymidylate Synthase Gene Concerning zntifulate Resistance of Plasmodium vivax

Background: the recently reported resistance to antimalarials contributes to making the control of malaria moredifficult. there is a need to evaluate the current antimalaria regimens to prevent this emerging problem. the aimof this study was to determine dihydrofolate reductase-thymidylate synthase gene mutation (pvdhfr) regardingantifulate resistance in plasmodium vivax.methods: from 2007 to 2009, 117 p. vivax infected blood samples collected from two regions of hormozganprovince, south of iran were analyzed using pcr, semi-nested-pcr and rflp methods.results: eighty four isolates (71.8 %) showed no mutation in pvdhfr gene of p. vivax known as wild type and 33(28.2%) of the samples revealed nine single (7.7%), twenty two double (18.8%) and two (1.7%) triple mutations.conclusion: genetic diversity was observed by molecular methods in pvdhfr gene of p. vivax in hormozganprovince suggests that the antifolate falciparum malaria drug (fansidar) is proportionally affecting p. vivax dhfrmutation. therefore, more studies to evaluate antimalarial drugs that should preferably be effective against both p.vivax and p. falciparum are recommended.