Highly genetically diverse variants of hepatitis C virus still predominate in Cameroon but with low frequency of mutations associated to resistance of NS5B polymerase-targeted antivirals.

Abstract

Background: Hepatitis C is of low endemicity (<2%) in the general population in Cameroon, with genotypes (GTs) 1, 2 and 4 reported frequently identified. In 2016, direct-acting antiviral agents (DAAs) were included in the Treatment Guidelines for hepatitis C in Cameroon. The aim of this study was to investigate hepatitis C virus (HCV) variability and frequency of NS5B naturally occurring polymorphisms and transmitted resistance-associated mutations or substitutions (RAMs or RASs) in DAAs-naïve patients.

Methods: From 240 HCV-infected, DAA-naïve individuals, the NS5B region of 92 samples were sequenced, genotyped by phylogeny using MEGA 11.0.13 software and analysed for polymorphisms conferring resistance to polymerase inhibitors using bioinformatics tools (Geno2Pheno HCV 0.92 and BioEdit version 7.2.5).

Results: Thirty-two GT1 (34.8%), 37 GT2 (40.2%), 22 GT4 (23.9%) and 1 GT5 (1.1%), 13 subtypes (1e, 1g, 1h, 1j, 1l, 2j, 2r, 4a, 4f, 4l, 4p, 4t and 5a) were found. Thirty-four GT2 sequences clustered together without any reference sequences and therefore could not be subtyped. The NS5B S282T resistance-associated substitutions was not detected in any sample. However, the polymorphisms of unreported resistance-associated impact in positions 316 and 321 were identified: C316H (8.7%), C316N (18.5%), V321I (6.5%) and a double mutant C316H/V321I (4.3%). Comparison of GTs obtained by a commercial PCR kit versus Sanger sequencing and phylogeny of the NS5B region, showed a discrepancy of 30%.

Conclusion: Genotype 5 was identified for the first time in Cameroon. The frequency of V321I and C316H/N polymorphism with unknown impact on NS5B polymerase inhibitors is increasing in Cameroon.