Plasmodium falciparum genetic factors rather than the hosts' are likely to drive resistance to ACTs in Ghana

Abstract Background: Artemisinin-based Combination Therapy (ACT) partner drugs, currently used in Ghana are lumefantrine, amodiaquine, and piperaquine. Plasmodium falciparum isolates with reduced susceptibility to these partner drugs may affect treatment outcome. Mutations in Pfmdr1 gene is linked to reduced parasite susceptibility to amodiaquine and lumefantrine. In addition, the potency of the partner drugs in vivo depends on the metabolism by the cytochrome P450 (CYP) enzyme in the host. Mutations in the CYP2C8 and CYP3A4 genes are linked to reduced metabolism of amodiaquine and lumefantrine respectively in vitro. This study investigated the host and parasite genetic factors affecting the susceptibility of the malaria parasite to ACT partner drugs.Methods: Archived samples from 240 patients aged ≤9years participating in antimalarial drug resistance survey in of Ghana and given AL or AA were selected and analyzed. Polymerase chain reaction (PCR) followed by Sanger sequencing was used to determine the polymorphisms in CYP2C8, CYP3A4, and Pfmdr1 genes. Results: For CYP3A4, all had wild type alleles suggesting that the hosts are good metabolizers of lumefantrine. For CYP2C8 60% had wild type alleles, 35% heterozygous and 5% homozygous recessive alleles suggesting efficient metabolism of amodiaquine by the hosts. For Pfmdr1 gene, at codon 86, 95% were wild type (N86) and 5% mutant (Y86). For codon 184, 36% were wild type (Y184) and 64% mutant (F184) while for codons 1034, 1042 and 1246, 100% (all) were wild type. The high prevalence of N86-F184-D1246 haplotype (NFD) suggest presence of parasites with reduced susceptibility to lumefantrine and not amodiaquine. Delayed clearance was observed in individuals with mutations in the Pfmdr1 gene and not Cytochrome 450 gene. Both synonymous and nonsynonymous mutations were observed in the Pfmdr1 at low prevalence. Conclusion: The outcome of this study indicates that parasite's genetic factors rather than the hosts' are likely to drive resistance to ACTs in Ghana.