title: Molecular epidemiology of Plasmodium vivax anti-folate resistance in India.
abstract: BACKGROUND
  Sulphadoxine and pyrimethamine are anti-folate drugs that show synergistic anti-malarial effect. Point mutations in dihydrofolate reductase (dhfr) and dihydropteorate synthatase (dhps) cause anti-folate drug resistance phenotype in human malaria parasites. This study presents pattern of point mutations in dhfr/dhps genes among Indian sub-continent.
  
  
  METHODS
  Microscopically diagnosed one hundred Plasmodium vivax field isolates were collected from five widely separated geographical regions of India. Dhfr and dhps genes were PCR amplified and sequenced. Previously published mutations data were collected and analyzed using Chi square test to identify geographical cluster of mutant/wild type genotypes.
  
  
  RESULTS
  Sequence analysis revealed single (S58R), double (S58R/S117N) and quadruple (F57L/S58R/T61M/S117T/) point mutations at dhfr and single (A383G) to double (A383G/A553G) mutations at dhps in P. vivax field isolates. In addition, three new mutations were also observed at dhfr. Both, dhfr and dhps genes revealed tandem repeat variations in field isolates. Dhps revealed very low mutation frequency (14.0%) compared to dhfr (50.70%). Comparative analysis revealed a progressive increase in frequency of quadruple mutant dhfr genotype (p<0.001) within five years in north-eastern state (Kamrup, Assam). Frequency of dhfr genotypes revealed three distinct geographical clusters of wild (northern India), double mutant (southern India), and quadruple mutant (north-eastern and island regions of India) on the Indian sub-continent.
  
  
  CONCLUSIONS
  Study suggests that SP may be susceptible to P. vivax in India, except Andaman and north-eastern state. The distinction of geographical regions with sensitive and resistant parasite phenotypes would be highly useful for designing and administering national anti-malarial drug policy.
authors.affiliation: Genetics and Molecular Biology Laboratory, National Institute of Malaria Research (NIMR), Sector-8, Dwarka, New Delhi 110077, India.
authors.forename: Surendra K
authors.initials: SK
authors.lastname: Prajapati
authors.forename: Hema
authors.initials: H
authors.lastname: Joshi
authors.forename: Vas
authors.initials: V
authors.lastname: Dev
authors.forename: Virendra K
authors.initials: VK
authors.lastname: Dua
mesh_terms: D019943:Amino Acid Substitution; D000962:Antimalarials / Q000494:pharmacology*; D016054:DNA, Protozoan; D004094:Dihydropteroate Synthase / Q000235:genetics; D004338:Drug Combinations; D005493:Folic Acid Antagonists / Q000494:pharmacology*; D005838:Genotype; D006801:Humans; D007194:India / Q000453:epidemiology; D008288:Malaria / Q000453:epidemiology* / Q000469:parasitology*; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D010802:Phylogeny; D058974:Phylogeography; D010966:Plasmodium vivax / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D017354:Point Mutation; D015800:Protozoan Proteins / Q000235:genetics; D011739:Pyrimethamine / Q000494:pharmacology; D017422:Sequence Analysis, DNA; D013413:Sulfadoxine / Q000494:pharmacology; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics
chemical_list: D000962:Antimalarials; D016054:DNA, Protozoan; D004338:Drug Combinations; D005493:Folic Acid Antagonists; D015800:Protozoan Proteins; C001205:fanasil, pyrimethamine drug combination; D013413:Sulfadoxine; D013762:Tetrahydrofolate Dehydrogenase; D004094:Dihydropteroate Synthase; D011739:Pyrimethamine