title: Insight into k13-propeller gene polymorphism and ex vivo DHA-response profiles from Cameroonian isolates.
abstract: The spread of Plasmodium falciparum resistance to artemisinin derivatives in Southeast Asia is a major source of concern and the emergence of resistance in Africa would have dramatic consequences, by increasing malaria mortality and morbidity. It is therefore urgent to implement regular monitoring in sentinel sites in sub-Saharan Africa using robust and easy-to-implement tools. The prevalence of k13-propeller mutations and the phenotypic profiles are poorly known in sub-Saharan Africa. Here, the k13-propeller polymorphism was compared to both ex vivo susceptibility to DHA and early parasitological and clinical responses to artemisinin combination therapy (ACT).
  
  
  
  Plasmodium falciparum isolates were collected in 2015 in Yaoundé (Cameroon) from patients treated with dihydroartemisinin-piperaquine combination. Samples were analysed for their susceptibility to artemisinin using the k13-propeller sequencing, the ex vivo ring-stage survival assay, the in vivo parasite positive rate and the clinical statute at day 2.
  
  
  
  None of the collected isolates revealed the presence of resistance mutations in the k13-propeller sequence. The median ring-stage survival rate for all the 64 interpretable isolates after a 6-hour pulse of 700 nM dihydroartemisinin was low, 0.49% (IQR: 0-1.3). Total parasite clearance was observed for 87.5% of patients and the remaining parasitaemic isolates (12.5%) showed a high reduction of parasite load, ranging from 97.5 to 99.9%. Clinical symptoms disappeared in 92.8% of cases.
  
  
  
  This study demonstrated the absence of k13-resistant genotypes in P. falciparum isolates from Cameroon. Only synonymous mutations were found with a low prevalence (4.3%). A good association between k13 genotypes and the ex vivo ring-stage survival assay or parasitological and clinical data was obtained. These results give a baseline for the long-term monitoring of artemisinin derivative efficacy in Africa.
authors.affiliation: Centre de Physiopathologie de Toulouse Purpan, INSERM U1043, CNRS UMR5282, Université de Toulouse, Toulouse, France.
authors.forename: Sandie
authors.initials: S
authors.lastname: Menard
authors.affiliation: Laboratoire d'Entomologie Médicale, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale, Yaoundé, Cameroon.
authors.forename: Joëlle Njila
authors.initials: JN
authors.lastname: Tchoufack
authors.affiliation: Laboratoire d'Entomologie Médicale, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale, Yaoundé, Cameroon.
authors.forename: Christelle Ngou
authors.initials: CN
authors.lastname: Maffo
authors.affiliation: Laboratoire d'Entomologie Médicale, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale, Yaoundé, Cameroon.|Faculté de Médecine et des Sciences Pharmaceutiques, Université de Douala, Douala, Cameroon.
authors.forename: Sandrine E
authors.initials: SE
authors.lastname: Nsango
authors.affiliation: Centre de Physiopathologie de Toulouse Purpan, INSERM U1043, CNRS UMR5282, Université de Toulouse, Toulouse, France.|Service de Parasitologie-Mycologie, CHU Toulouse, Toulouse, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Iriart
authors.affiliation: UMR MIVEGEC, IRD 224-CNRS5290-UM, Institut de Recherche pour le développement, Montpellier, France.
authors.forename: Luc
authors.initials: L
authors.lastname: Abate
authors.affiliation: UMR MIVEGEC, IRD 224-CNRS5290-UM, Institut de Recherche pour le développement, Montpellier, France.
authors.forename: Majoline Tchioffo
authors.initials: MT
authors.lastname: Tsapi
authors.affiliation: Laboratoire d'Entomologie Médicale, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale, Yaoundé, Cameroon.
authors.forename: Parfait H
authors.initials: PH
authors.lastname: Awono-Ambéné
authors.affiliation: Dispensaire de Nkol-Eton, BP894, Yaounde, Cameroon.
authors.forename: Francis A
authors.initials: FA
authors.lastname: Abega Mekongo
authors.affiliation: UMR MIVEGEC, IRD 224-CNRS5290-UM, Institut de Recherche pour le développement, Montpellier, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Morlais
authors.affiliation: Centre de Physiopathologie de Toulouse Purpan, INSERM U1043, CNRS UMR5282, Université de Toulouse, Toulouse, France. berry.a@chu-toulouse.fr.|Service de Parasitologie-Mycologie, CHU Toulouse, Toulouse, France. berry.a@chu-toulouse.fr.
authors.forename: Antoine
authors.initials: A
authors.lastname: Berry
mesh_terms: D000293:Adolescent; D000328:Adult; D000962:Antimalarials / Q000494:pharmacology* / Q000627:therapeutic use; D037621:Artemisinins / Q000494:pharmacology* / Q000627:therapeutic use; D002163:Cameroon; D002648:Child; D004351:Drug Resistance; D005260:Female; D006801:Humans; D016778:Malaria, Falciparum / Q000188:drug therapy / Q000469:parasitology*; D008297:Male; D008875:Middle Aged; D021261:Parasitic Sensitivity Tests; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D017354:Point Mutation; D011110:Polymorphism, Genetic; D011446:Prospective Studies; D015800:Protozoan Proteins / Q000235:genetics*; D011804:Quinolines / Q000627:therapeutic use; D016896:Treatment Outcome; D014838:Volunteers; D055815:Young Adult; D010879:Piperazines
chemical_list: D000962:Antimalarials; D037621:Artemisinins; D015800:Protozoan Proteins; D011804:Quinolines; C039060:artenimol; C034759:piperaquine; D010879:Piperazines
keywords: Artemisinins; Cameroon; Clearance; Dihydroartemisinin; K13; Plasmodium falciparum; Resistance; Ring-stage survival assay