title: Monitoring resistance of Plasmdium vivax: point mutations in dihydrofolate reductase gene in isolates from Central China.
abstract: BACKGROUND
  Malaria still represents a significant public health problem in China, and the cases dramatically increased in Central China after 2001. Antifolate resistance in Plasmodium vivax is caused by point mutations in genes encoding dihydrofolate reductase (pvdhfr) and dihydropteroate synthase (pvdhps). In this study, we used direct sequencing to investigate genetic variation in pvdhfr of malaria patients' samples from Central China.
  
  
  RESULTS
  Among all the samples, 21.4% were wild-type, whereas mutations were detected at three codons (58, 61 and 117) including single mutant (34.6%) and double mutants (43.8%). The most prevalent mutant allele was the one with double mutation at codons 58 and 117 (24.6%). Three types of single mutation (S58R, T61M and S117N) were found in 2.1%, 11.8% and 20.9% of parasite isolates, respectively. The four P. vivax parasite populations in Central China also differed in pvdhfr allele frequencies.
  
  
  CONCLUSIONS
  This study suggested that P. vivax in Central China may be relatively susceptible to pyrimethamine. And it also highlights genotyping in the pvdhfr genes remains a useful tool to monitor the emergence and spread of P. vivax pyrimethamine resistance.
authors.affiliation: National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, PR China.
authors.forename: Fang
authors.initials: F
authors.lastname: Huang
authors.forename: Shuisen
authors.initials: S
authors.lastname: Zhou
authors.forename: Shaosen
authors.initials: S
authors.lastname: Zhang
authors.forename: Weidong
authors.initials: W
authors.lastname: Li
authors.forename: Hongwei
authors.initials: H
authors.lastname: Zhang
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics; D000962:Antimalarials / Q000494:pharmacology*; D002681:China; D016054:DNA, Protozoan / Q000235:genetics; D004351:Drug Resistance; D006801:Humans; D016780:Malaria, Vivax / Q000469:parasitology; D020125:Mutation, Missense; D010966:Plasmodium vivax / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D017354:Point Mutation; D011110:Polymorphism, Genetic; D017422:Sequence Analysis, DNA; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics*
chemical_list: D000962:Antimalarials; D016054:DNA, Protozoan; D013762:Tetrahydrofolate Dehydrogenase