Parasites bearing a single copy of the multi-drug resistance gene (pfmdr-1) with wild-type SNPs predominate amongst Plasmodium falciparum isolates from Malawi.
We genotyped 160 P. falciparum infections from Malawi for pfmdr-1 copy number changes and SNPs associated with in vivo tolerance and poor in vitro sensitivity to the component drugs of Coartem. We also measured in vitro susceptibility of 49 of these isolates to a variety of drugs in clinical use or with a potential for use in Africa. All 160 infections carried a single copy of pfmdr-1 but 34% exhibited sequence variation at 4 of the 5 polymorphic sites in pfmdr-1. Isolates carrying 86-Asn and 184-Tyr pfmdr-1 alleles were significantly less sensitive (p<0.001) to mefloquine, lumefantrine, artemether and dihydroartemisinin compared with those bearing 86-Tyr and 184-Phe polymorphisms. This study provides baseline measures prior to policy change: continued surveillance for changes in baseline drug susceptibility, pfmdr-1 copy number and SNPs, and other putative Coartem resistance loci will be necessary to provide an early warning of emerging Coartem resistance in this setting.
Malawi-Liverpool-Wellcome Trust Clinical Research Programme, College of Medicine, University of Malawi, Blantyre, Malawi. snkhoma@sfbrgenetics.org
Standwell
S
Nkhoma
Shalini
S
Nair
Mavuto
M
Mukaka
Malcolm E
ME
Molyneux
Stephen A
SA
Ward
Timothy J C
TJ
Anderson
D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D000962:Antimalarials / Q000494:pharmacology*; D000077611:Artemether, Lumefantrine Drug Combination; D037621:Artemisinins / Q000494:pharmacology*; D002675:Child, Preschool; D004338:Drug Combinations; D018432:Drug Resistance, Multiple; D004983:Ethanolamines / Q000494:pharmacology*; D005449:Fluorenes / Q000494:pharmacology*; D018628:Gene Dosage; D006801:Humans; D007223:Infant; D020128:Inhibitory Concentration 50; D016778:Malaria, Falciparum / Q000469:parasitology*; D008295:Malawi; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics*; D020125:Mutation, Missense; D021261:Parasitic Sensitivity Tests; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D020641:Polymorphism, Single Nucleotide
D000962:Antimalarials; D000077611:Artemether, Lumefantrine Drug Combination; D037621:Artemisinins; D004338:Drug Combinations; D004983:Ethanolamines; D005449:Fluorenes; D027425:ATP-Binding Cassette, Sub-Family C Proteins; C513498:Mdr1 protein, Plasmodium falciparum