Abstract
Worldwide, ~71 million people are infected with hepatitis C virus (HCV). Claudin-1 (CLDN1) and occludin (OCLN), both tetraspanins of epithelial tight junctions, are entry receptors for HCV. Previously, we generated anti-CLDN1 and anti-OCLN monoclonal antibodies (mAbs), both of which strongly inhibit HCV entry into hepatocytes. However, the relevance of CLDN1 and OCLN in persistent HCV infection remains unclear. In the present study, we evaluated the involvement of CLDN1 and OCLN in persistent HCV infection using the mAbs against CLDN1 (clone 3A2) and OCLN (clone 1-3). Interestingly, both mAbs significantly reduced intracellular HCV RNA levels in a cell culture system. Additionally, the anti-OCLN mAb reduced serum HCV levels in chronic HCV-infected human liver chimeric (PXB) mice (often used as an in vivo HCV infection model), whereas the anti-CLDN1 mAb did not have this effect. These results suggest that the OCLN molecule contributes to maintaining persistent HCV infection in vivo. In further investigation, we determined whether combinations of NS5B inhibitor, nesbuvir, and the anti-OCLN mAb had anti-HCV effects on persistent HCV-infected PXB mice. Administration of nesbuvir and control IgG caused a breakthrough of serum HCV levels in all mice, whereas nesbuvir and anti-OCLN mAb combinations caused the breakthrough at a later phase in only one of three mice. Thus, anti-OCLN mAb seems to suppress the occurrence of resistant viruses against nesbuvir. Based on these results, we suggest that the anti-OCLN mAb, which could be combined with direct-acting antiviral agents, might be a potential candidate antiviral agent in HCV therapeutics.
