K13 propeller domain mutations and pfmdr1 amplification in isolates of Plasmodium falciparum collected from Thai-Myanmar border area in 2006-2010.

Abstract

The K13 propeller domain mutation and pfmdr1 amplification have been proposed as useful molecular markers for detection and monitoring of artemisinin resistant Plasmodium falciparum Welch, 1897. Genomic DNA isolates of P. falciparum was extracted from 235 dried blood spot or whole blood samples collected from patients with uncomplicated falciparum malaria residing in areas along the Thai-Myanmar border during 2006-2010. Nested polymerase chain reaction (PCR) and sequencing were performed to detect mutations in K13 propeller domain of P. falciparum at codon 427-709. Pfmdr1 gene copy number was determined by SYBR Green I real-time PCR. High prevalence of pfmdr1 multiple copies was observed (42.5% of isolates). The presence of K13 mutations was low (40/235, 17.2%). Seventeen mutations had previously been reported and six mutations were newly detected. The C580Y was found in two isolates (0.9%). The F446I, N458Y and P574L mutations were commonly detected. Seven isolates had both K13 mutation and pfmdr1 multiple copies. It needs to be confirmed whether parasites harbouring both K13 mutation and pfmdr1 multiple copies and/or the observed new mutations of K13 propeller domain are associated with clinical artemisinin resistance.