title: Genetic structure of Plasmodium vivax and Plasmodium falciparum in the Bannu district of Pakistan.
abstract: BACKGROUND
  Plasmodium vivax and Plasmodium falciparum are the major causative agents of malaria. While knowledge of the genetic structure of malaria parasites is useful for understanding the evolution of parasite virulence, designing anti-malarial vaccines and assessing the impact of malaria control measures, there is a paucity of information on genetic diversity of these two malaria parasites in Pakistan. This study sought to shed some light on the genetic structure of P. vivax and P. falciparum in this understudied region.
  
  
  METHODS
  The genetic diversities of P. vivax and P. falciparum populations from the densely populated, malaria-endemic Bannu district of Pakistan were evaluated by analysis of their merozoite surface protein (msp) genes by PCR-RFLP. Specifically, the Pvmsp-3alpha and Pvmsp-3beta genes of P. vivax and the Pfmsp-1 and Pfmsp-2 genes of P. falciparum were analysed.
  
  
  RESULTS
  In P. vivax, genotyping of Pvmsp-3alpha and Pvmsp-3beta genes showed a high level of diversity at these loci. Four distinct allele groups: A (1.9 kb), B (1.5 kb), C (1.2 kb), and D (0.3 kb) were detected for Pvmsp-3alpha, type A being the most prevalent (82%). Conversely, amplification of the P. vivax msp-3beta locus produced two allele groups: A (1.7-2.2 kb, 62%) and B (1.4-1.5 kb, 33%), with 5% mixed-strain infections. Restriction analysis of Pvmsp-3alpha and Pvmsp-3beta yielded 12 and 8 distinct alleles, respectively, with a combined mixed genotype prevalence of 20%. In P. falciparum, all three known genotypes of Pfmsp-1 and two of Pfmsp-2 were observed, with MAD20 occurring in 67% and 3D7/IC in 65% of the isolates, respectively. Overall, 24% P. falciparum samples exhibited mixed-strain infections.
  
  
  CONCLUSIONS
  These results indicate that both P. vivax and P. falciparum populations in Pakistan are highly diverse.
authors.affiliation: Department of Medicine, Division of Infectious Diseases, University of California - San Francisco, P,O, Box 0811, San Francisco, CA 94143-0811, USA.
authors.forename: Lubna
authors.initials: L
authors.lastname: Khatoon
authors.forename: Frederick N
authors.initials: FN
authors.lastname: Baliraine
authors.forename: Mariangela
authors.initials: M
authors.lastname: Bonizzoni
authors.forename: Salman A
authors.initials: SA
authors.lastname: Malik
authors.forename: Guiyun
authors.initials: G
authors.lastname: Yan
mesh_terms: D000953:Antigens, Protozoan / Q000235:genetics; D040342:Genetic Structures; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D020066:Merozoite Surface Protein 1 / Q000235:genetics; D010154:Pakistan; D010963:Plasmodium falciparum / Q000235:genetics* / Q000302:isolation & purification; D010966:Plasmodium vivax / Q000235:genetics* / Q000302:isolation & purification; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D015800:Protozoan Proteins / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D000953:Antigens, Protozoan; D020066:Merozoite Surface Protein 1; D015800:Protozoan Proteins; C065974:merozoite surface protein 2, Plasmodium; C089133:merozoite surface protein 3, Plasmodium