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.