title: Practical PCR genotyping protocols for Plasmodium vivax using Pvcs and Pvmsp1.
abstract: BACKGROUND
  Plasmodium vivax is the second most prevalent malaria parasite affecting more than 75 million people each year, mostly in South America and Asia. In addition to major morbidity this parasite is associated with relapses and a reduction in birthweight. The emergence and spread of drug resistance in Plasmodium falciparum is a major factor in the resurgence of this parasite. P. vivax resistance to drugs has more recently emerged and monitoring the situation would be helped, as for P. falciparum, by molecular methods that can be used to characterize parasites in field studies and drug efficacy trials.
  
  
  METHODS
  Practical PCR genotyping protocols based on polymorphic loci present in two P. vivax genetic markers, Pvcs and Pvmsp1, were developed. The methodology was evaluated using 100 P. vivax isolates collected in Thailand.
  
  
  CONCLUSIONS
  Analysis revealed that P. vivax populations in Thailand are highly diverse genetically, with mixed genotype infections found in 26 % of the samples (average multiplicity of infection = 1.29). A large number of distinguishable alleles were found for the two markers, 23 for Pvcs and 36 for Pvmsp1. These were generally randomly distributed amongst the isolates. A total of 68 distinct genotypes could be enumerated in the 74 isolates with a multiplicity of infection of 1.
  
  
  CONCLUSIONS
  These results indicate that the genotyping protocols presented can be useful in the assessment of in vivo drug efficacy clinical trials conducted in endemic areas and for epidemiological studies of P. vivax infections.
authors.affiliation: Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. noi@tropmedres.ac
authors.forename: Mallika
authors.initials: M
authors.lastname: Imwong
authors.forename: Sasithon
authors.initials: S
authors.lastname: Pukrittayakamee
authors.forename: Anne Charlotte
authors.initials: AC
authors.lastname: Grüner
authors.forename: Laurent
authors.initials: L
authors.lastname: Rénia
authors.forename: Frank
authors.initials: F
authors.lastname: Letourneur
authors.forename: Sornchai
authors.initials: S
authors.lastname: Looareesuwan
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: White
authors.forename: Georges
authors.initials: G
authors.lastname: Snounou
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D017931:DNA Primers / Q000737:chemistry; D016054:DNA, Protozoan / Q000097:blood / Q000737:chemistry / Q000302:isolation & purification; D005787:Gene Frequency; D023061:Gene Order; D005838:Genotype; D006801:Humans; D020066:Merozoite Surface Protein 1 / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D010966:Plasmodium vivax / Q000145:classification* / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000379:methods*; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics*; D012680:Sensitivity and Specificity; D016415:Sequence Alignment; D013785:Thailand
chemical_list: D017931:DNA Primers; D016054:DNA, Protozoan; D020066:Merozoite Surface Protein 1; D015800:Protozoan Proteins; C041595:circumsporozoite protein, Protozoan