Mutations within the CD81‐Binding Sites and Hypervariable Region 2 of the Envelope 2 Protein: Correlation with Treatment Response in Hepatitis C Virus–Infected Patients

The hepatitis C virus (HCV) envelope 2 (E2) protein interacts with the cellular receptor CD81 in vitro. Within E2, 2 CD81-binding sites were described. E2-CD81 interaction has been shown to modulate B and T cell function. The clinical importance of mutations within the CD81-binding sites and overlapping hypervariable region 2 (HVR2) in correlation with response to antiviral treatment is unknown. Fifty-five patients infected with HCV-1b or HCV-3a underwent interferon-alpha-based treatment. The E2 gene, comprising the CD81-binding sites and HVR2, was sequenced from pretreatment serum samples. The number of mutations within CD81-binding sites was not correlated with virologic treatment response in HCV-1b- and HCV-3a-infected patients. Within HVR2, the total number of mutations was significantly higher in HCV-1b-infected patients with a sustained response to interferon-alpha-based treatment (3.9; range, 1-6) than in those with relapse (2.9; range, 1-5) or those who did not respond (2.8; range, 1-5) (P = .041). However, when the same analyses were based only on functionally nonconserved mutations, no significant differences were observed.