Real-Time PCR for Dihydrofolate Reductase Gene Single-Nucleotide Polymorphisms in Plasmodium vivax Isolates

Abstract

ABSTRACT Mutations in the dhfr gene of Plasmodium vivax ( pvdhfr ) are associated with resistance to the antifolate antimalarial drugs. Polymorphisms in the pvdhfr gene were assessed by hybridization probe technology on the LightCycler instrument with 134 P. vivax -infected blood samples from Turkey ( n = 24), Azerbaijan ( n = 39), Thailand ( n = 16), Indonesia ( n = 53), and travelers ( n = 19). Double mutations (S58R and S117N) or quadruple mutations (F57L/I, S58R, T61M, and S117N) in the pvdhfr genes were found in all Thai samples (100%). pvdhfr mutant-type alleles were significantly more common in samples from travelers (42%) than in those from patients from Indonesia (5%). Surprisingly, the pvdhfr single - mutation allele (S117N) was identified at a high frequency in parasites from Turkey and Azerbaijan (71 and 36%, respectively), where sulfadoxine-pyrimethamine is not recommended for the treatment of P. vivax malaria by the World Health Organization and the Malaria National Programs.