Identification of thePlasmodium vivax mdr‐Like Gene(pvmdr1)and Analysis of Single‐Nucleotide Polymorphisms among Isolates from Different Areas of Endemicity

Abstract

Because of the lack of methods for continuous in vitro culture of Plasmodium vivax, little is known about drug-resistance mechanisms in this malaria-causing parasite. Therefore, identification of all the genes potentially involved in drug resistance and of molecular markers related to drug resistance would provide a framework for studying the incidence and spread of drug-resistant P. vivax strains. We have identified the P. vivax orthologue of the pfmdr1 gene (pvmdr1), which was shown to have a role in the drug resistance of Plasmodium falciparum. Comparison of the alignments of both nucleotide and amino acid sequences of pvmdr1 with those of other Plasmodium multidrug-resistance genes revealed an open-reading frame of 4392 base pairs encoding a deduced protein of 1464 amino acids. Nucleotide polymorphisms at 2 codons of the pvmdr1 gene--Y976F and F1076L--were found in 14 of 23 P. vivax isolates from different areas of endemicity, including Thailand, Indonesia, Turkey, Azerbaijan, and French Guyana.

Single-nucleotide polymorphism, linkage disequilibrium and geographic structure in the malaria parasite Plasmodium vivax: prospects for genome-wide association studies

“…All but one single-mutant allele carried the F1076L change; the only allele carrying the Y976F change alone (i. e., not co-occurring with the F1076L change) came from Granada, Brazil. These findings lend further support to the hypothesis that a two-step mutational trajectory (F1076L followed by Y976F) at the pvmdr-1 locus leads to CQ resistance [21]. If this hypothesis is correct, molecular detection of F1076L single mutants may provide an early warning about the risk of emerging CQ resistance before the drug-resistant phenotype itself can be detected in populations.…”

“…We focused on two nonsynonymous substitutions in pvmdr-1 thought to be associated with CQ resistance, Y976F and F1076L [21-23]. Double-mutant alleles accounted for all or nearly all samples from Cambodia and Vietnam, while wild-type alleles predominated in Brazil.…”

“…K76T mutant alleles of the P. falciparum orthologue of pvcrt-o , which encodes the protein chloroquine resistance transporter (PfCRT), confer CQ resistance to this species [46], but the limited data available to date fail to support associations between mutations in pvcrt-o alleles and CQ resistance in P. vivax [44,45]. We also typed one synonymous (at codon 4065) and five nonsynonymous (N89 S, N500 D, M908L, Y976F, and F1076L) SNPs previously described at the multidrug resistance 1 gene of P. vivax ( pvmdr-1 ) [21,22,24,45], which encodes a P-glycoprotein of the family of ATP binding cassette (ABC) transporters. The Y976F mutation (TAC→TTC) has been associated with CQ resistance in Southeast Asia [22] and Papua New Guinea [23].…”

“…The Y976F mutation (TAC→TTC) has been associated with CQ resistance in Southeast Asia [22] and Papua New Guinea [23]. Interestingly, the Y976F change is rarely, if ever, observed in alleles that do not carry the F1076L (TTT→CTT) change, suggesting a two-step mutation pathway leading to CQ resistance [21]. All SNPs were genotyped, under contract, by K-Biosciences (Cambridge, UK), with an amplifluor assay [47,48].…”

Single-Nucleotide Polymorphism and Copy Number Variation of the Multidrug Resistance-1 Locus of Plasmodium vivax: Local and Global Patterns

“…3,[10][11][12] Interestingly, the Y976F change has been reported to be rare in alleles that do not carry the F1076L (TTT!CTT) change, consistent with a two-step mutation pathway (F1076L followed by Y976F) putatively leading to CQ resistance. 13,14 Similar to P. falciparum, 15 susceptibility to CQ in P. vivax appears to be also modulated by pvmdr-1 copy number. Amplification of the pvmdr-1 gene correlates with increased susceptibility to CQ and decreased susceptibility to amodiaquine, artesunate and mefloquine in vitro.…”