Abstract
BackgroundThe mutations in Plasmodium falciparum chloroquine resistance transporter (pfcrt), multidrug resistance 1 (pfmdr1), dihydrofolate reductase (pfdhfr), dihydropteroate synthase (pfdhps) and ATPase (pfatp6) genes were associated with anti-malaria drug resistance. The aim of this study was to investigate the prevalence of polymorphisms in pfcrt, pfmdr1, pfdhfr, pfdhps and pfatp6 in Yunnan Province. Finger-prick blood samples were collected from malaria-positive patients from Yunnan Province in 2009-2010. Single-nucleotide polymorphisms (SNPs) in the resistance-related genes were analysed by various PCR-based methods.ResultsA total of 108 blood samples were collected. Although chloroquine has not been used to treat falciparum malaria for nearly 30 years, 95.3% of the parasites still carried the pfcrt K76T mutation, whereas the majority of isolates displayed the wild-type pfmdr1 N86 and D1246 sequences. The molecular level of sulphadoxine–pyrimethamine resistance in P. falciparum was high. The most prevalent mutation was pfdhfr C59R (95.9%), whereas the frequencies of the quadruple, triple and double mutants were 22.7% (N51I/C59R/S108N/I164L), 51.5% (N51I/C59R/S108N, N51I/C59R/I164L and C59R/S108N/ I164L) and 21.6% (N51I/ C59R, C59R/S108N and C59R/I164L), respectively. A437G (n = 77) and K540E (n = 71) were the most prevalent mutations in pfdhps, and 52.7% of the samples were double mutants, among which A437G/K540E was the most common double mutation (37/49). Quadruple mutants were found in 28.0% (26/93) of samples. A total of 8.6% of isolates (8/93) carried the S436A/A437G/A581G triple mutation. No mutations were found in pfatp6 codons 623 or 769, but another two mutations (N683K and R756K) were found in 4.6% (3/97) and 9.2% (6/97) of parasite isolates, respectively.ConclusionsThis study identified a high frequency of mutations in pfcrt, pfdhfr and pfdhps associated with CQ and SP resistance in P. falciparum and no mutations linked to artemisinin resistance (pfatp6). Molecular epidemiology should be included in routine surveillance protocols and used to provide complementary information to assess the appropriateness of the current national anti-malarial drug policy.
Highlights
The mutations in Plasmodium falciparum chloroquine resistance transporter, multidrug resistance 1, dihydrofolate reductase, dihydropteroate synthase and ATPase genes were associated with anti-malaria drug resistance
56 patients was local malaria cases and 52 patients were contracted from Kachin State of Myanmar
Pfcrt has been demonstrated to be a major determinant of CQ resistance in P. falciparum, and the K76T mutation has been widely used as a reliable marker for CQ resistance in epidemiological studies [28,29,30]
Summary
The mutations in Plasmodium falciparum chloroquine resistance transporter (pfcrt), multidrug resistance 1 (pfmdr1), dihydrofolate reductase (pfdhfr), dihydropteroate synthase (pfdhps) and ATPase (pfatp6) genes were associated with anti-malaria drug resistance. The aim of this study was to investigate the prevalence of polymorphisms in pfcrt, pfmdr, pfdhfr, pfdhps and pfatp in Yunnan Province. Despite significant reductions in the overall malaria burden in the 20th century, the disease still represents a significant public health problem in China, especially in Yunnan Province [2]. Falciparum malaria is found in only two provinces in China, the Yunnan and Hainan Provinces [4]. The malaria situation in Yunnan Province near the Myanmar border remains serious. Yunnan Province is located in southern China; it includes 131 counties and borders
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