Identification of a Novel Hepatitis C Virus Genotype From Punjab, India: Expanding Classification of Hepatitis C Virus Into 8 Genotypes

Background. Hepatitis C virus (HCV) exhibits great genetic diversity and is classified into 7 genotypes (GTs), with varied geographic prevalence. Until the recent development of pangenotypic direct-acting antiviral regimens, the determination of HCV GT was necessary to inform optimal treatment. Methods. Plasma samples with unresolved GT using standard commercial genotyping methods were subjected to HCV full-genome sequencing, and phylogenetic analysis was performed to assign GT. Results. Four patients, previously classified as GT5 by LiPA or Abbott RealTime polymerase chain reaction assays, were identified as infected with a novel HCV GT. This novel HCV GT, GT8, is genetically distinct from previously identified HCV GT1-7 with > 30% nucleotide sequence divergence to the established HCV subtypes. All 4 patients were originally from Punjab, India, but now reside in Canada and are epidemiologically unlinked. Despite presence of baseline resistance-associated substitutions within the GT8 virus of all 4 patients (NS3: V36L, Q80K/R; NS5A: Q30S, Y93S), all patients achieved a sustained virologic response; 2 treated with sofosbuvir/velpatasvir/voxilaprevir for 8 weeks, 1 with sofosbuvir/ledipasvir plus ribavirin for 24 weeks and 1 with sofosbuvir plus daclatasvir for 12 weeks. Conclusions. The discovery of a novel HCV GT8 confirms the circulation of this newly identified lineage in the human population.