Genetic structure of Plasmodium vivax and Plasmodium falciparum in the Bannu district of Pakistan.
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.
Khatoon
Lubna
L
Department of Medicine, Division of Infectious Diseases, University of California - San Francisco, P,O, Box 0811, San Francisco, CA 94143-0811, USA.
Baliraine
Frederick N
FN
Bonizzoni
Mariangela
M
Malik
Salman A
SA
Yan
Guiyun
G
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
D000953:Antigens, Protozoan; D020066:Merozoite Surface Protein 1; D015800:Protozoan Proteins; C065974:merozoite surface protein 2, Plasmodium; C089133:merozoite surface protein 3, Plasmodium