Background: Hepatitis C virus (HCV) resistance-associated variants (RAVs) have been shown to adversely affect treatment response of direct-acting antivirals. Identifying pre-existing RAVs and transmission networks among HIV/HCV genotype 1 (G1)-infected patients from Poland will assist in shaping surveillance strategies for HCV.
Methods: NS3 and NS5A sequences were obtained from samples of 112 direct-acting antiviral-naive G1 patients (45 G1a and 67 G1b), of which 74 were chronically infected and 38 were diagnosed with acute hepatitis C (AHC). RAVs were identified using geno2pheno, and 98 concatenated NS3/NS5A alignments were constructed to identify transmission clusters using a maximum likelihood approach.
Results: G1a was notably more prevalent compared with G1b among men-having-sex-with-men (MSM) (60.0% vs. 31.3%, P = 0.004), AHC cases (46.7% vs. 25.4%, P = 0.019), and patients diagnosed with syphilis (52.2% vs. 24.5%, P = 0.009). The overall NS3/NS5A RAVs frequency was 14.3% with variants occurring more often in G1a compared with G1b (27.5% vs. 5.2%, P = 0.005), mostly for NS3 due to the high prevalence of polymorphism Q80K. NS5A RAVs were only found in 2.9% of sequences. Significant clustering was observed for 73.5% of the Polish sequences, however, more common in G1a MSM compared with G1b (50.0% vs. 25.9%, P = 0.02). The identified clusters contained sequences originating from up to 5 Polish cities, located within a mean distance of 370 km.
Conclusions: Close clustering of Polish strains suggests the presence of compartmentalized epidemics of MSM that fuel the spread of G1a variants. Particularly patients with AHC form a national transmission network, including clusters enriched with the NS3 Q80K polymorphism.