title: Distribution of pfmdr1 polymorphisms in Plasmodium falciparum isolated from Southern Thailand.
abstract: BACKGROUND
  Drug resistance in Plasmodium falciparum is a major problem in malaria control especially along the Thai-Myanmar and Thai-Cambodia borders. To date, a few molecular markers have been identified for anti-malarial resistance in P. falciparum, including the P. falciparum chloroquine resistance transporter (pfcrt) and the P. falciparum multidrug resistance 1 (pfmdr1). However no information is available regarding the distribution pattern of these gene polymorphisms in the parasites from the Thai-Malaysia border. This study was conducted to compare the distribution pattern of the pfcrt and pfmdr1 polymorphisms in the parasites from the lower southern provinces, Thai-Malaysia border and the upper southern provinces, Thai-Myanmar border. In addition, in vitro sensitivities of anti-malarial drugs including chloroquine, mefloquine, quinine, and artesunate were determined.
  
  
  METHODS
  In all, 492 P. falciparum-positive blood samples were collected from the lower southern provinces: Songkhla, Yala and Narathiwas. From the upper southern part of Thailand, Ranong and Chumphon, 66 samples were also collected. Polymorphisms of the pfcrt and the pfmdr1 gene were determined using PCR techniques. In vitro sensitivities of anti-malarial drugs were determined using radioisotopic method.
  
  
  RESULTS
  All parasites from both areas contained the pfcrt 76 T allele. The pfmdr1 86Y allele was significantly more common in the parasites isolated from the lower southern areas. In contrast, the pfmdr1 184F allele was predominant among the parasites from the upper southern areas especially Ranong. In addition, the parasites from Ranong contained higher copy numbers than the parasites from other provinces. All adapted parasite isolates exhibited CQ-resistant phenotype. Neither QN nor MQ resistance was detected in these isolates.
  
  
  CONCLUSIONS
  The parasites from Thai-Malaysia border exhibited different resistant patterns compared to other areas along the international border of Thailand. This information will be useful for anti-malarial drug policy in Thailand.
authors.affiliation: Department of Parasitology, Phramongkutklao College of Medicine, Ratchawithi Rd, Bangkok 10400, Thailand. mathirut@pmk.ac.th.
authors.forename: Mathirut
authors.initials: M
authors.lastname: Mungthin
authors.forename: Somchai
authors.initials: S
authors.lastname: Intanakom
authors.forename: Nantana
authors.initials: N
authors.lastname: Suwandittakul
authors.forename: Preeyaporn
authors.initials: P
authors.lastname: Suida
authors.forename: Sakultip
authors.initials: S
authors.lastname: Amsakul
authors.forename: Naruemon
authors.initials: N
authors.lastname: Sitthichot
authors.forename: Suwich
authors.initials: S
authors.lastname: Thammapalo
authors.forename: Saovanee
authors.initials: S
authors.lastname: Leelayoova
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism; D000962:Antimalarials / Q000494:pharmacology*; D004351:Drug Resistance; D006801:Humans; D016778:Malaria, Falciparum / Q000188:drug therapy*; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism; D010963:Plasmodium falciparum / Q000187:drug effects / Q000235:genetics*; D011110:Polymorphism, Genetic; D015800:Protozoan Proteins / Q000235:genetics* / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D013785:Thailand
chemical_list: D018528:ATP-Binding Cassette Transporters; D000962:Antimalarials; D026901:Membrane Transport Proteins; C416369:PfCRT protein, Plasmodium falciparum; D015800:Protozoan Proteins; C059987:mdr gene protein, Plasmodium