A comprehensive survey of polymorphisms conferring anti-malarial resistance in Plasmodium falciparum across Pakistan

Malaria Journal

Research

Francis Hombhanje¹  Aamer A Khattak²  Salman A Malik²  Toshihiro Mita³  Christopher G Jacob⁴  Elena M Artimovich⁴  Christopher V Plowe⁵  Meera Venkatesan⁵  Farida Nighat⁶  Muhammad F Nadeem⁷ 

[1] Centre for Health Research, Divine Word University, Madang, Papua, New Guinea;Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan;Department of Molecular and Cellular Parasitology, Juntendo University, Tokyo, Japan;Howard Hughes Medical Institute/Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD, USA;Howard Hughes Medical Institute/Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD, USA;WorldWide Antimalarial Resistance Network Molecular Module, University of Maryland School of Medicine, Baltimore, MD, USA;Islamic International Medical College, Rawalpindi, Pakistan;King Edward Medical University, Lahore, Pakistan;Department of Biochemistry and Molecular Biology, University of Gujrat, Gujrat, Pakistan;

关键词: Plasmodium falciparum;    Malaria;    Pakistan;    Drug resistance;    Sulphadoxine-pyrimethamine;    Chloroquine;    ACT;    pfcrt;    pfmdr1;    pfdhfr;    pfdhps;   

DOI  :  10.1186/1475-2875-12-300

 received in 2013-05-30, accepted in 2013-08-26,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundFew studies have been conducted in Pakistan to determine the efficacy of chloroquine and sulphadoxine-pyrimethamine (SP), which remain in use as treatment for Plasmodium vivax and in combination with artesunate to treat Plasmodium falciparum, respectively. In this study, samples from several sites across Pakistan were characterized to determine prevalence of molecular resistance markers in the P. falciparum chloroquine resistance transporter (pfcrt), multidrug resistance (pfmdr1), dihydrofolate reductase (pfdhfr) and dihydropteroate synthase (pfdhps) genes and the origin of chloroquine-resistant P. falciparum parasites.MethodsMicroscopy-confirmed malaria parasite-positive blood samples from 801 patients across the country were collected in 2011. Of these, 171 infections were identified by polymerase chain reaction (PCR) as P. falciparum and analysed by pyrosequencing for mutations conferring chloroquine resistance (pfcrt codons 72–76), multidrug resistance (pfmdr1 N86Y, Y184F, S1034C, N1042D and D1246Y), pyrimethamine resistance (pfdhfr, C50R, N51I, C59R, S108N and I164L) and sulphadoxine resistance (pfdhps, S436A, A437G, K540E, A581G and A613T/S). pfmdr1 gene copy number variation was determined by real-time PCR, and microsatellites flanking the pfcrt locus were typed to determine the origin of the chloroquine-resistant haplotype.ResultsThe pfcrt K76T mutation was found in all samples as part of the S72/V73/M74/N75/T76 (SVMNT) haplotype. Microsatellites flanking pfcrt showed high similarity to the signature found in India and Papua New Guinea. pfmdr1 N86Y was found in 20% of samples and all samples harboured a single copy of the pfmdr 1 gene. The pfdhfr double mutation C59R + S108N was present in 87% of samples while the pfdhfr triple mutant (N51I + C59R + S108N) was not detected. Pfdhps A437G was found in 60% of samples. Pure pfdhps K540E was rare, at 4%, but mixed genotype 540 K/E was found in 77% of samples. Similarly, pure pfdhps A581G was found in 4% of the isolates while mixed 581A/G was found in 39% of samples.ConclusionsThese results suggest an emerging problem with multidrug resistant P. falciparum in Pakistan. The chloroquine resistance genotype has reached complete fixation in the population, with a microsatellite pattern indicative of a selective sweep. Moreover, the prevalence of mutations in both pfdhfr and pfdhps, albeit without the presence of the pfdhfr triple mutant, indicates that continued monitoring is warranted to assess whether SP remains efficacious as a partner drug for artesunate for the treatment of P. falciparum.

【 授权许可】

Unknown   
© Khattak et al.; licensee BioMed Central Ltd. 2013. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.