Genetic diversity among Plasmodium falciparum field isolates in Pakistan measured with PCR genotyping of the merozoite surface protein 1 and 2.
BACKGROUND
The genetic diversity of Plasmodium falciparum has been extensively studied in various parts of the world. However, limited data are available from Pakistan. This study aimed to establish molecular characterization of P. falciparum field isolates in Pakistan measured with two highly polymorphic genetic markers, i.e. the merozoite surface protein 1 (msp-1)and 2 (msp-2).


METHODS
Between October 2005 and October 2007, 244 blood samples from patients with symptomatic blood-slide confirmed P. falciparum mono-infections attending the Aga Khan University Hospital, Karachi, or its collection units located in Sindh and Baluchistan provinces, Pakistan were collected. The genetic diversity of P. falciparum was analysed by length polymorphism following gel electrophoresis of DNA products from nested polymerase chain reactions (PCR) targeting block 2 of msp-1 and block 3 of msp-2, including their respective allelic families KI, MAD 20, RO33, and FC27, 3D7/IC.


RESULTS
A total of 238/244 (98%) patients had a positive PCR outcome in at least one genetic marker; the remaining six were excluded from analysis. A majority of patients had monoclonal infections. Only 56/231 (24%) and 51/236 (22%) carried multiple P. falciparum genotypes in msp-1 and msp-2, respectively. The estimated total number of genotypes was 25 msp-1 (12 KI; 8 MAD20; 5 RO33) and 33 msp-2 (14 FC27; 19 3D7/IC).


CONCLUSIONS
This is the first report on molecular characterization of P. falciparum field isolates in Pakistan with regards to multiplicity of infection. The genetic diversity and allelic distribution found in this study is similar to previous reports from India and Southeast Asian countries with low malaria endemicity.
Ghanchi
Najia K
NK
Department of Pathology and Microbiology, Aga Khan University, Stadium Road, PO Box 3500, Karachi 74800, Pakistan. najia.ghanchi@aku.edu
Mårtensson
Andreas
A
Ursing
Johan
J
Jafri
Sana
S
Bereczky
Sándor
S
Hussain
Rabia
R
Beg
Mohammad A
MA
D000293:Adolescent; D000328:Adult; D000818:Animals; D000953:Antigens, Protozoan / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D016172:DNA Fingerprinting; D005260:Female; D014644:Genetic Variation; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016778:Malaria, Falciparum / Q000469:parasitology*; D008297:Male; D020066:Merozoite Surface Protein 1 / Q000235:genetics; D017720:Molecular Epidemiology; D010154:Pakistan; D010963:Plasmodium falciparum / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D016133:Polymerase Chain Reaction / Q000379:methods*; D012150:Polymorphism, Restriction Fragment Length; D015800:Protozoan Proteins / Q000235:genetics*; D055815:Young Adult
D000953:Antigens, Protozoan; D020066:Merozoite Surface Protein 1; D015800:Protozoan Proteins; C065974:merozoite surface protein 2, Plasmodium