Discordant Temporal Evolution of Pfcrt and Pfmdr1 Genotypes and Plasmodium falciparum In Vitro Drug Susceptibility to 4-Aminoquinolines after Drug Policy Change in French Guiana

Abstract

Analysis of the evolution of drug target genes under changing drug policy is needed to assist monitoring of Plasmodium falciparum drug resistance in the field. Here we genotype Pfcrt and Pfdmr1 of 700 isolates collected in French Guiana from 2000 (5 years after withdrawal of chloroquine) to 2008, i.e., the period when the artemether-lumefantrine combination was progressively introduced and mefloquine was abandoned. Gene sequencing showed fixation of the 7G8-type Pfcrt SMVNT resistance haplotype and near fixation of the NYCDY Pfdmr1 haplotype. Pfdmr1 gene copy number correlated with 50% inhibitory concentrations of mefloquine and halofantrine (r ‫؍‬ 0.64 and 0.47, respectively, n ‫؍‬ 547); its temporal changes paralleled changes in in vitro mefloquine susceptibility. However, the molecular parameters studied did not account for the regained in vitro susceptibility to chloroquine and showed a poor correlation with susceptibility to artemether, lumefantrine, or quinine. Identification of novel markers of resistance to these antimalarials is needed in this South American area.

Adaptive evolution of malaria parasites in French Guiana: Reversal of chloroquine resistance by acquisition of a mutation in pfcrt

“…Genomic DNA was prepared using the QIAmp DNA Blood Kit (Qiagen). Conditions for PCR and targeted sequencing of pfcrt exon 2 (harboring codons 72-76) and polymorphic regions of pfmdr1 were previously described (16). A 121-bp fragment encompassing the complete exon 10 of pfcrt (harboring codon 350) was PCR-amplified and Sanger-sequenced.…”

“…We have previously reported that a significant proportion of P. falciparum parasites from French Guiana have a CQ IC 50 below the adopted resistance threshold of 100 nM, despite elevated prevalence of K76T, suggesting a reduced predictive value of this marker, at least in this region of South America (16). In this study, we pursued a genotypic and phenotypic survey, including wholegenome sequencing and gene-editing experiments, which led us to identify a molecular marker of drug susceptibility.…”

Étude de la résistance dePlasmodium falciparumaux antipaludiques au sein du réseau international des Instituts Pasteur (RIIP-Palu)

“…trouve que nos données indiquent que certains marqueurs pertinents pour prédire la résistance aux antipaludiques dans certaines régions (comme l'Afrique par exemple) doivent être réévalués pour des contextes particuliers comme Madagascar [22] ou la Guyane française [23]. Ces données indiquent que l'évolution des populations parasitaires diffère dans différents contextes épidémiologiques et géographiques.…”

Role of K13 Mutations in Artemisinin-Based Combination Therapy

“…This possibility is suggested by the observation that recurrent isolates were significantly more likely to have multiple pfmdr1 copies (53/65 [81.5%]) than admission isolates (377/726 [51.9%]; P < .001, Fisher exact test). Another explanation is that parasites having a single pfmdr1 copy may be overexpressing pfmdr1 mRNA, as described in South America [8]. These 2 hypotheses require investigation.…”