Molecular analysis of pfatp6 and pfmdr1 polymorphisms and their association with in vitro sensitivity in Plasmodium falciparum isolates from the Thai-Myanmar border

• Published in: Acta tropica 2011-10, Vol.120 (1-2), p.130-135
• Main Authors: Phompradit, Papichaya, Wisedpanichkij, Raewadee, Muhamad, Poonuch, Chaijaroenkul, Wanna, Na-Bangchang, Kesara
• Format: Article
• Language: English
• Subjects: alleles; Antimalarials - pharmacology; Artemisinins - pharmacology; Artesunate; Biological and medical sciences; Calcium-Transporting ATPases - genetics; chloroquine; Chloroquine - pharmacology; codons; Drug Resistance - genetics; Gene amplification; General aspects; Genetic Markers - genetics; Inhibitory Concentration 50; Malaria, Falciparum - parasitology; Medical sciences; Mefloquine - pharmacology; Multidrug resistance; Multidrug Resistance-Associated Proteins - genetics; Myanmar; parasites; Parasitic Sensitivity Tests; pfatp6; pfmdr1; Pharmacogenetics; Plasmodium falciparum; Plasmodium falciparum - drug effects; Plasmodium falciparum - genetics; Polymorphism, Genetic; Protozoan Proteins - genetics; quinine; Quinine - pharmacology; restriction fragment length polymorphism; reverse transcriptase polymerase chain reaction; Single nucleotide polymorphism; Thailand
• ISSN: 0001-706X; 1873-6254
• DOI: 10.1016/j.actatropica.2011.07.003

[Display omitted] ► Amplification of pfmdr1 appears to be the candidate molecular marker of reduced susceptibility of P. falciparum isolates to mefloquine, artesunate and quinine. ► Mutation at codon 86 of pfmdr1 was associated with a significant increase in the susceptibility of P. falciparum to mefloquine and quinine. ► There was no association between mutation or amplification of pfatp6 and in vitro sensitivity of P. falciparum isolates to mefloquine, quinine, chloroquine and artesunate. The association between pfatp6, pfmdr1 polymorphisms (gene mutation and amplification) and in vitro susceptibility to mefloquine (MQ), artesunate (AS), quinine (QN), and chloroquine (CQ) was investigated in a total of sixty-three Plasmodium falciparum isolates collected from the Thai-Myanmar border. The mutations of pfatp6 at codons R37K, G639D, S769N, and I898I and of pfmdr1 at codons N86Y, Y184F, N1042D, and D1246Y were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Pfatp6 and pfmdr1 gene copy numbers were analyzed by quantitative real time-polymerase chain reaction (qRT-PCR). In vitro susceptibility test was successful in 58 culture-adapted isolates. Median (range) IC50 values for MQ, AS, QN, and CQ were 28.96 (3.4–100.5), 1.74 (0.8–5.57), 223.9 (14.99–845.47), and 69.93 (9.6–183.18) nM, respectively. There was a significant positive correlation (R2=0.58) of parasite susceptibility to MQ, AS, and QN. Twelve isolates showed marked decline in susceptibility to AS [median (range) IC50=3.78 (3.07–5.57) nM]. Almost all isolates carried wild-type pfatp6 and pfmdr1 alleles at the investigated codons, while only three isolates (5%) carried pfmdr1 mutation alleles at codon 86. Mutation at codon 86 was associated with a significant increase in the susceptibility of parasite isolates to MQ and QN. All of the sixty-three isolates carried only one pfatp6 copy number. Thirty-three out of the 58 isolates showed increase in pfmdr1 gene copies, which was associated with reduced in vitro susceptibility to MQ, AS, and QN. No association between mutation or amplification of pfatp6 gene and in vitro susceptibility of P. falciparum isolates was found.