title: Molecular markers of resistance to sulphadoxine-pyrimethamine during intermittent preventive treatment of pregnant women in Benin.
abstract: BACKGROUND
  The prevention of malaria faces with the repeated emergence of Plasmodium falciparum resistance to drugs, often involving point mutations of the target gene. In the pregnant woman, currently the WHO recommendation is the administration of an intermittent preventive treatment (IPTp) with sulphadoxine-pyrimethamine. Sulphadoxine-pyrimethamine (SP) resistance has increased for several years in Africa, stressing the need for alternative molecules. In this context, the first randomized clinical trial comparing the efficacy of SP and mefloquine for IPTp has been conducted recently in Benin. Using samples from this trial, the current study evaluated and quantified the prevalence of mutations on the pfdhfr and pfdhps genes as well as the copy number of the pfmdr1 gene in parasites from P. falciparum-infected pregnant women before first and second IPTp administration, and at delivery.
  
  
  METHODS
  PCR-restriction fragment length polymorphism of polymorphic codons of the pfdhfr gene (51, 59, 108, and 164) was performed. The identification of mutations in three codons of the pfdhps gene (436, 437 and 540) was achieved by PCR and sequencing. Copy number quantification for pfmdr1 gene was performed using real-time PCR.
  
  
  RESULTS
  Results show a high prevalence rate of mutant parasites in women taking IPTp with sulphadoxine-pyrimethamine or mefloquine. The prevalence of triple and quadruple mutants was high before first drug regimen administration (79/93, 85%), and remained similar until delivery. Infection with mutant parasites was not correlated with low birth weight nor placental infection. In all samples, the copy number of pfmdr1 gene was equal to one.
  
  
  CONCLUSIONS
  The clinical trial comparing SP and mefloquine efficacy during IPTp showed SP remained efficacious in preventing low birth weight. The present study shows a high prevalence of triple and quadruple mutations implicated in SP resistance. Although the pfdhfr/pfdhps triple and quadruple mutations were frequent, there was no evidence of correlation between these genotypes and the lack of efficacy of SP in the context of IPTp. Nevertheless, it is now obvious that SP will soon be compromised in whole Africa. Molecular markers have been recommended to monitor SP efficacy for IPTp, but given the current prevalence of mutant parasites their usefulness is questionable.
authors.affiliation: Institut de Recherche pour le Développement (IRD), Mère et enfant face aux infections tropicales (UMR216), Paris Cedex, France.
authors.forename: Gwladys
authors.initials: G
authors.lastname: Bertin
authors.forename: Valérie
authors.initials: V
authors.lastname: Briand
authors.forename: Diana
authors.initials: D
authors.lastname: Bonaventure
authors.forename: Ambre
authors.initials: A
authors.lastname: Carrieu
authors.forename: Achille
authors.initials: A
authors.lastname: Massougbodji
authors.forename: Michel
authors.initials: M
authors.lastname: Cot
authors.forename: Philippe
authors.initials: P
authors.lastname: Deloron
mesh_terms: D000328:Adult; D000962:Antimalarials / Q000008:administration & dosage / Q000494:pharmacology*; D001541:Benin; D015415:Biomarkers; D018890:Chemoprevention / Q000379:methods*; D002986:Clinical Trials as Topic; D004094:Dihydropteroate Synthase / Q000235:genetics; D004338:Drug Combinations; D004351:Drug Resistance; D005260:Female; D018628:Gene Dosage; D005838:Genotype; D006801:Humans; D016778:Malaria, Falciparum / Q000469:parasitology / Q000517:prevention & control*; D015767:Mefloquine / Q000008:administration & dosage / Q000494:pharmacology; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics; D020125:Mutation, Missense; D010963:Plasmodium falciparum / Q000187:drug effects*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000469:parasitology / Q000517:prevention & control*; D011739:Pyrimethamine / Q000008:administration & dosage / Q000494:pharmacology*; D013413:Sulfadoxine / Q000008:administration & dosage / Q000494:pharmacology*; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics
chemical_list: D000962:Antimalarials; D015415:Biomarkers; D004094:Dihydropteroate Synthase; D004338:Drug Combinations; D015767:Mefloquine; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D011739:Pyrimethamine; D013413:Sulfadoxine; D013762:Tetrahydrofolate Dehydrogenase; C513498:Mdr1 protein, Plasmodium falciparum; C001205:fanasil, pyrimethamine drug combination