Artemether resistance in vitro is linked to mutations in PfATP6 that also interact with mutations in PfMDR1 in travellers returning with Plasmodium falciparum infections.
AuthorsPillai, Dylan R
Staines, Henry M
KAUST Grant NumberKUK-I1-012-43
MetadataShow full item record
AbstractBACKGROUND: Monitoring resistance phenotypes for Plasmodium falciparum, using in vitro growth assays, and relating findings to parasite genotype has proved particularly challenging for the study of resistance to artemisinins. METHODS: Plasmodium falciparum isolates cultured from 28 returning travellers diagnosed with malaria were assessed for sensitivity to artemisinin, artemether, dihydroartemisinin and artesunate and findings related to mutations in pfatp6 and pfmdr1. RESULTS: Resistance to artemether in vitro was significantly associated with a pfatp6 haplotype encoding two amino acid substitutions (pfatp6 A623E and S769N; (mean IC50 (95% CI) values of 8.2 (5.7 - 10.7) for A623/S769 versus 623E/769 N 13.5 (9.8 - 17.3) nM with a mean increase of 65%; p = 0.012). Increased copy number of pfmdr1 was not itself associated with increased IC50 values for artemether, but when interactions between the pfatp6 haplotype and increased copy number of pfmdr1 were examined together, a highly significant association was noted with IC50 values for artemether (mean IC50 (95% CI) values of 8.7 (5.9 - 11.6) versus 16.3 (10.7 - 21.8) nM with a mean increase of 87%; p = 0.0068). Previously described SNPs in pfmdr1 are also associated with differences in sensitivity to some artemisinins. CONCLUSIONS: These findings were further explored in molecular modelling experiments that suggest mutations in pfatp6 are unlikely to affect differential binding of artemisinins at their proposed site, whereas there may be differences in such binding associated with mutations in pfmdr1. Implications for a hypothesis that artemisinin resistance may be exacerbated by interactions between PfATP6 and PfMDR1 and for epidemiological studies to monitor emerging resistance are discussed.
CitationPillai DR, Lau R, Khairnar K, Lepore R, Via A, et al. (2012) Artemether resistance in vitro is linked to mutations in PfATP6 that also interact with mutations in PfMDR1 in travellers returning with Plasmodium falciparum infections. Malaria Journal 11: 131. Available: http://dx.doi.org/10.1186/1475-2875-11-131.
SponsorsWe thank the expert technical assistance of the medical laboratory staff in Parasitology at the Public Health Laboratory in Toronto. DRP, RL and KK are financially supported by the Ontario Agency for Health Protection and Promotion, AV by the Fondazione Roma, RL by the King Abdullah University of Science and Technology (KAUST; award number KUK-I1-12-43) and SK and HMS by the EDTCP (project code: IP.2008.31060.003).
PubMed Central IDPMC3422158
CollectionsPublications Acknowledging KAUST Support
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