Polymorphisms of pfcrt, pfmdr1, and K13-propeller genes in imported falciparum malaria isolates from Africa in Guizhou province, China

BACKGROUND: Imported falciparum malaria from Africa has become a key public health challenge in Guizhou Province since 2012. Understanding the polymorphisms of molecular markers of drug resistance can guide selection of antimalarial drugs for the treatment of malaria. This study was aimed to analyze the polymorphisms of pfcrt, pfmdr1, and K13-propeller among imported falciparum malaria cases in Guizhou Province, China. METHOD: Fifty-five imported falciparum malaria cases in Guizhou Province during 2012–2016 were included in this study. Their demographic information and filter paper blood samples were collected. Genomic DNA of Plasmodium falciparum was extracted from the blood samples, and polymorphisms of pfcrt, pfmdr1, and K13-propeller were analyzed with nested PCR amplification followed by sequencing. Data were analyzed with the SPSS17.0 software. RESULTS: The prevalence of pfcrt K76T, pfmdr1 N86Y, and pfmdr1 Y184F mutation was 56.6, 22.2, and 72.2%, respectively, in imported falciparum malaria cases in Guizhou Province. We detected two mutant haplotypes of pfcrt, IET and MNT, with IET being more commonly found (54.7%), and five mutant haplotypes of pfmdr1, of which NFD was the most frequent (53.7%). There were totally 10 combined haplotypes of pfcrt and pfmdr1, of which the haplotype IETNFD possessed a predominance of 28.8%. In addition, three nonsynonymous mutations (S459T, C469F, and V692L) and two synonymous mutations (R471R and V589V) were detected in K13-propeller, all having prevalence less than 6.0%. In particular, a candidate K13 resistance mutation, C469F, was identified for the first time from Democratic Republic of the Congo with the prevalence of 2.0%. CONCLUSIONS: The high prevalence of IET haplotype of pfcrt and NFD haplotype of pfmdr1 suggests the presence of chloroquine, artemether/lumefantrine, and dihydroartemisinin/piperaquine resistance in these cases. Therefore cautions should be made to artemisinin therapy for P. falciparum in Africa. Continuous monitoring of anti-malarial drug efficacy in imported malaria cases is helpful for optimizing antimalarial drug therapy in Guizhou Province, China.