"Although K13-propeller mutations previously associated with delayed parasite clearance in Cambodia were not identified, 26 K13-propeller mutations were identified in both recent samples and pre-ACT infections."
"Baseline parasitaemia was associated with the K13-propeller mutation ( P value = 0.37 [linear regression, adjusted for site])."
"The increased K13-propeller gene mutations previously associated with DPC among P. falciparum populations from 2013 to 2014 in Grande Comore (a ~20 % increment) may present new challenges in the ACT efficacy in the future [ xref , xref ]."
"Although wide-scale studies that analyzed P . falciparum isolates from numerous sub-Saharan African countries including Ethiopia found no mutations in the parasite’s K13-propeller gene, which is associated with artemisinin resistance in Southeast Asia [ xref , xref ] the threat is clear."
"It has been suggested that Y493H, I543T, R539T, and C580Y mutations in K13-propeller gene are associated with prolonged parasite survival ex vivo; Y493H, R539T, and C580Y mutations are linked to in vivo delayed parasite clearance; and M476I mutation is related to artemisinin tolerance in vitro [ xref , xref , xref , xref ] ."
"In GrpA, artemisinin resistance and K13-propeller polymorphisms also associated with down-regulation of genes involved in DNA replication ( xref and xref )."
"F32-DU whole genome sequencing (WGS) revealed that resistance to trioxaquine was associated with the same non-synonymous mutation in the propeller domain of the K13 protein (M476I) that was found in the F32-ART lineage."
"We found low prevalence of K13 propeller domain mutations, which are associated with artemisinin resistance in Asia, but one mutation previously identified in northern Uganda, 675V, was seen in 2.0% of samples, including 5.5% from the 3 northernmost sites."
"In addition, mutations in the P. falciparum K13 gene (PF3D7_1343700) that encodes the kelch propeller domain were associated with in vitro resistance to artemisinin and with delayed clearance after artemisinin treatment in southern Asia [ xref , xref , xref ]."
"Our observation is consistent with those in previous reports from Kenya [ xref ], Angola [ xref ], Mozambique [ xref ], Senegal [ xref ], Ugandan [ xref ] as well as other areas of Sub-Saharan Africa [ xref ], Caribbean’s Haiti [ xref ], and South Asia’ Bangladesh [ xref ], where the K13-propeller gene mutations associated with artemisinin resistance were absent."
"Furthermore, molecular surveillance in Dakar has demonstrated the emergence of polymorphisms in the K13 propeller domain gene, which is associated with in vitro and in vivo resistance to artemisinin in Asia [ xref – xref ]."
"These observations suggest that not all K13-propeller mutations are associated with artemisinin resistance, and that secondary loci are involved in resistance Asian parasites, but not in African parasites."
"Numerous independent K13 propeller mutations associated with resistance have emerged independently across the region ( xref , xref ), and the frequencies of some mutations, notably, Cys580Tyr, have risen in multiple geographical areas."
"Meanwhile, artemisinin tolerance in vitro was associated with the M476I mutation of K13-propeller [ xref ]."
"The role of the A578S amino acid substitution is unclear, but it occurs near the most common K13-propeller mutation (C580Y), which has been associated with delayed parasite clearance in Southeast Asia and with tolerance to artemisinin in vitro ( xref )."
"Recently association of K13-propeller polymorphism with artemisinin resistance in vitro and in vivo has been proposed [ xref ]."
"Both transcriptional phenotypes are closely associated with K13-propeller polymorphism, and may enable parasites to survive artemisinin by repairing and replenishing their oxidatively-damaged proteins before advancing through the cell cycle."
"Mutations in the P. falciparum k13 gene that encodes the kelch propeller domain were associated with in vitro resistance to artemisinin and with delayed clearance after artemisinin treatment in Southeast Asia [ xref , xref – xref ]."
"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."
"The presence of K13 propeller mutations within Africa, where parasite clearance is generally rapid, suggests that not all K13 propeller mutations are associated with resistance, that secondary loci are involved in resistance and found in Asia but not in Africa thus far, or that the resistance phenotype is masked by high levels of antimalarial immunity."
"The K13-propeller mutations associated with artemisinin-resistance were mainly found in Southeast Asia, with C580Y being the predominant one."
"The sensitivity and specificity of this definition may be enhanced by using only the subset of K13 -propeller mutations that have been associated with artemisinin resistance in clinical and in vitro studies, or combining them with other molecular markers."
"Interestingly, a cluster of seven mutants were identified that were sensitive to artemisinin, including one with a mutation in the K13-propeller gene that is associated with resistance xref , xref , xref ."
"A mutant K13 propeller domain has now been associated with artemisinin resistance in Cambodia and in the Greater Mekong Region ( xref – xref , xref , xref )."
"Genomic analysis of Cambodian parasite isolates have identified four prevalent K13-propeller mutations (Y493H, R539T, I543T, and C580Y) that are associated with elevated ring-stage survival rates In vitro and long parasite clearance half-lives (>5 h) [ xref ]."
"Specifically, three mutations (C580Y, R539T and Y493H) in the K13-propeller gene were strongly associated with increased ring stage survival and delayed parasite clearance [ xref ]."
"Major mutations in the K13 propeller domain associated with artemisinin resistance in the Mekong region (C580Y, R539T and Y493H) were absent, but F446I and two previously undescribed mutations (V603E and V454I) were identified."
"Based on Keap1 function, a hypothetical model could be that in steady state conditions, the wild-type K13-propeller domain binds to uTF (a putative, unidentified transcription factor functionally equivalent to human Nrf2) allowing its ubiquitination and proteosomal degradation."