title: The geographical distribution of allele polymorphisms of Plasmodium vivax in different regions of Thailand.
abstract: OBJECTIVE
  To investigate the genetic structure of Plasmodium vivax circumsporozoite surface protein (PvCSP) and P. vivax merozoite surface protein 1 (PvMSP1) genes from field isolates of malaria parasites from four different regions of Thailand.
  
  
  METHODS
  The data was collected by cross-sectional survey, consisting of 273 P. vivax infected blood samples from malaria clinics in 4 different border regions of Thailand from February 2008 to February 2009. The dried blood spots were extracted for DNA and Plasmodium species confirmed by species-specific primer sets. PvCSP and PvMSP1 genes were amplified and their population genetics were analyzed by using the Heterozygosity (H) formula, F-STAT and LIAN programs.
  
  
  RESULTS
  There was considerable variation in the PvMSP1 gene within 2 fragments for which HE was 0.8303, whereas PvCSP showed low HE at 0.1418. Significant differences in allele frequencies between sites were quantified by Fst, Linkage disequilibrium (LD). The results showed PvMSP1 F2; Fst = 0.063, p = 0.07; PvMSP1 F2 RFLP pattern; Fst = 0.154, p = 0.005; PvMSP1 F3; Fst = 0.23, p = 0.005 and the overall loci showed Fst = 0.151, p = 0.005 (Fisher's exact test). All values of Index association (I(S)A) were non-significant. There was no evidence of LD within the P. vivax populations.
  
  
  CONCLUSIONS
  H(E) at each locus of the PvMSP1 gene showed significant differences in allele frequencies between sites.
authors.affiliation: Department of Parasitology and Entomology, Faculty of Public Health, Mahidol University, Bangkok, Thailand.
authors.forename: Varakorn
authors.initials: V
authors.lastname: Kosaisavee
authors.forename: Ian
authors.initials: I
authors.lastname: Hastings
authors.forename: Alister
authors.initials: A
authors.lastname: Craig
authors.forename: Usa
authors.initials: U
authors.lastname: Lek-Uthai
mesh_terms: D000940:Antigenic Variation / Q000235:genetics*; D000953:Antigens, Protozoan / Q000235:genetics*; D005787:Gene Frequency; D006801:Humans; D016780:Malaria, Vivax / Q000469:parasitology*; D020066:Merozoite Surface Protein 1 / Q000235:genetics*; D010966:Plasmodium vivax / Q000235:genetics*; D011110:Polymorphism, Genetic; D012150:Polymorphism, Restriction Fragment Length; D015800:Protozoan Proteins / Q000235:genetics*; D016036:Seroepidemiologic Studies; D013785:Thailand
chemical_list: D000953:Antigens, Protozoan; D020066:Merozoite Surface Protein 1; D015800:Protozoan Proteins; C041595:circumsporozoite protein, Protozoan