title: In vitro susceptibility to quinine and microsatellite variations of the Plasmodium falciparum Na+/H+ exchanger transporter (Pfnhe-1) gene in 393 isolates from Dakar, Senegal.
abstract: BACKGROUND
  Although the World Health Organization recommends replacing quinine (QN) by artesunate due to its increased efficacy and the higher tolerance to the drug in both adults and children, QN remains a first-line treatment for severe malaria, especially in Africa. Investigations of microsatellite Pfnhe-1 ms4760 polymorphisms in culture-adapted isolates from around the world have revealed that an increase in the number of DNNND amino acid motifs was associated with decreased QN susceptibility, whereas an increase in the number of DDNHNDNHNND motifs was associated with increased QN susceptibility.
  
  
  METHODS
  In this context, to further analyse associations between Pfnhe-1 ms4760 polymorphisms and QN susceptibility, 393 isolates freshly collected between October 2009 and January 2010 and July 2010 and February 2011, respectively, at the Hôpital Principal de Dakar, Senegal were assessed ex vivo for QN susceptibility, and their genes were amplified and sequenced.
  
  
  RESULTS
  Of the 393 Plasmodium falciparum clinical isolates collected, 145 were successfully cultured. The 145 QN IC50s ranged from 2.1 to 1291 nM, and 17 isolates (11.7%) exceed the QN reduced susceptibility threshold of 611 nM. Among the 393 P. falciparum clinical isolates, 47 different alleles were observed. The three most prevalent profiles were ms4760-1 (no = 72; 18.3%), ms4760-3 (no = 65; 16.5%) and ms4760-7 (no = 40; 10.2%). There were no significant associations observed between QN IC50 values and i) the number of repeats of DNNND in block II (p = 0.0955, Kruskal-Wallis test); ii) the number of repeats of DDNHNDNHNND in block V (p = 0.1455, Kruskal-Wallis test); or iii) ms4760 profiles (p = 0.1809, Kruskal-Wallis test).
  
  
  CONCLUSIONS
  Pfnhe-1 ms4760 was highly diverse in parasite isolates from Dakar (47 different profiles). Three profiles (ms4760-1, ms4760-3 and ms4760-7) were predominant. The number of repeats for block II (DNNND) or block V (DDNHNDNHNND) was not significantly associated with QN susceptibility. New studies, and especially in vivo studies, are necessary to confirm the role of Pfnhe-1 ms4760 as a marker of QN resistance.
authors.affiliation: Département d'Infectiologie de Terrain, Unité de Parasitologie, Institut de Recherche Biomédicale des Armées, Marseille, France.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Pascual
authors.forename: Bécaye
authors.initials: B
authors.lastname: Fall
authors.forename: Nathalie
authors.initials: N
authors.lastname: Wurtz
authors.forename: Mansour
authors.initials: M
authors.lastname: Fall
authors.forename: Cheikhou
authors.initials: C
authors.lastname: Camara
authors.forename: Aminata
authors.initials: A
authors.lastname: Nakoulima
authors.forename: Eric
authors.initials: E
authors.lastname: Baret
authors.forename: Bakary
authors.initials: B
authors.lastname: Diatta
authors.forename: Khadidiatou Ba
authors.initials: KB
authors.lastname: Fall
authors.forename: Pape Saliou
authors.initials: PS
authors.lastname: Mbaye
authors.forename: Yaya
authors.initials: Y
authors.lastname: Diémé
authors.forename: Raymond
authors.initials: R
authors.lastname: Bercion
authors.forename: Hervé
authors.initials: H
authors.lastname: Bogreau
authors.forename: Sébastien
authors.initials: S
authors.lastname: Briolant
authors.forename: Christophe
authors.initials: C
authors.lastname: Rogier
authors.forename: Boubacar
authors.initials: B
authors.lastname: Wade
authors.forename: Bruno
authors.initials: B
authors.lastname: Pradines
mesh_terms: D000328:Adult; D000962:Antimalarials / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D005838:Genotype; D006801:Humans; D016778:Malaria, Falciparum / Q000469:parasitology*; D021261:Parasitic Sensitivity Tests; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D015800:Protozoan Proteins / Q000235:genetics; D011803:Quinine / Q000494:pharmacology*; D012675:Senegal; D017422:Sequence Analysis, DNA; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics*
chemical_list: D000962:Antimalarials; D016054:DNA, Protozoan; D015800:Protozoan Proteins; D017923:Sodium-Hydrogen Exchangers; D011803:Quinine