Selection of pfcrt K76 and pfmdr1 N86 Coding Alleles after Uncomplicated Malaria Treatment by Artemether-Lumefantrine in Mali

Abstract

Background: Artemether-lumefantrine is a highly effective artemisinin-based combination therapy that was adopted in Mali as first-line treatment for uncomplicated Plasmodium falciparum malaria. This study was designed to measure the efficacy of artemether-lumefantrine and to assess the selection of the P. falciparum chloroquine resistance transporter (pfcrt) and P. falciparum multi-drug resistance 1 (pfmdr1) genotypes that have been associated with drug resistance.

Methods: A 28-day follow-up efficacy trial of artemether-lumefantrine was conducted in patients aged 6 months and older suffering from uncomplicated falciparum malaria in four different Malian areas during the 2009 malaria transmission season. The polymorphic genetic markers MSP2, MSP1, and Ca1 were used to distinguish between recrudescence and reinfection. Reinfection and recrudescence were then grouped as recurrent infections and analyzed together by PCR-restriction fragment length polymorphism (RFLP) to identify candidate markers for artemether-lumefantrine tolerance in the P. falciparum chloroquine resistance transporter (pfcrt) gene and the P. falciparum multi-drug resistance 1 (pfmdr1) gene.

Results: Clinical outcomes in 326 patients (96.7%) were analyzed and the 28-day uncorrected adequate clinical and parasitological response (ACPR) rate was 73.9%. The total PCR-corrected 28-day ACPR was 97.2%. The pfcrt 76T and pfmdr1 86Y population prevalence decreased from 49.3% and 11.0% at baseline (n = 337) to 38.8% and 0% in patients with recurrent infection (n = 85); p = 0.001), respectively.

Conclusion: Parasite populations exposed to artemether-lumefantrine in this study were selected toward chloroquine-sensitivity and showed a promising trend that may warrant future targeted reintroduction of chloroquine or/and amodiaquine.

Keywords: Artemether-lumefantrine; Mali; Pfcrt; Pfmdr1; Plasmodium falciparum.

Figure 1

Study profile.

Figure 2

Parasitemia clearance.

Figure 3

Gametocytemia clearance.

Figure 4

Pfcrt allele frequency. D0 = date of enrollment; Day R = date of recurrent infection.

Figure 5

Pfmdr1 allele frequency. D0 = date of enrollment; Day R = date of recurrent infection.

Figure 6

Gel photo illustrations for MSP2, MSP1, and Ca1 (D0 = Day 0 and DF = Failure Day). (Plate 1). DNA band of Plasmodium falciparum MSP2. (Plate 2). DNA band of P. falciparum MSP1. (Plate 3). DNA band of microsatellite Ca1.