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Genetic diversity among Plasmodium falciparum field isolates in Pakistan measured with PCR genotyping of the merozoite surface protein 1 and 2

Najia K Ghanchi12, Andreas Mårtensson34, Johan Ursing3, Sana Jafri1, Sándor Bereczky35, Rabia Hussain1 and Mohammad A Beg1*

Author Affiliations

1 Department of Pathology and Microbiology, Aga Khan University, Stadium Road, PO Box 3500, Karachi 74800, Pakistan

2 Department of Biotechnology, University of Karachi, University Road, Karachi, Pakistan

3 Malaria Research Lab, Infectious Diseases Unit, Department of Medicine, Karolinska University Hospital/Karolinska Institutet, Retziusväg 10, S-171 77 Stockholm, Sweden

4 Division of Global Health (IHCAR), Department of Public Health Sciences, Karolinska Institutet, Nobelsväg 9, S-171 77 Stockholm, Sweden

5 Centre for Microbiological Preparedness, Swedish Institute for Infectious Disease Control, Nobelsväg 18, SE-171 82 Stockholm, Sweden

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Malaria Journal 2010, 9:1  doi:10.1186/1475-2875-9-1

Published: 1 January 2010

Abstract

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.