Full-Length Sequence Analysis of Chloroquine Resistance Transporter Gene inPlasmodium falciparumIsolates from Sabah, Malaysia

Abstract

Chloroquine resistance (CQR) in falciparum malaria was identified to be associated with several mutations in the chloroquine resistance transporter gene (pfcrt) that encodes the transmembrane transporter in digestive vacuole membrane of the parasite. This study aimed to investigate the point mutations across the full-lengthpfcrtinPlasmodium falciparumisolates in Sabah, Malaysia. A total of 31P. falciparumpositive samples collected from Keningau, Kota Kinabalu, and Kudat, Sabah, were analyzed.pfcrtwas PCR amplified and cloned prior to sequence analysis. This study showed that all the previously described 10 point mutations associated with CQR at codons 72, 74, 75, 76, 97, 220, 271, 326, 356, and 371 were found with different prevalence. Besides, two novel point mutations, I166V and H273N, were identified with 22.5% and 19.3%, respectively. Three haplotypes, namely, CVMNK (29%), CVIET (3.2%), and SVMNT (67.7%), were identified. High prevalence of SVMNT amongP. falciparumisolates from Sabah showed that these isolates are closer to theP. falciparumisolates from Papua New Guinea rather than to the more proximal Southeast Asian CVIET haplotype. Full-length analysis ofpfcrtshowed that chloroquine resistantP. falciparumin Sabah is still prevalent despite the withdrawal of chloroquine usage since 1979.