Inhibition Of Hepatitis C Virus Infection By Anti-cluadin1 Antibody In Vitro

BACKGROUND & OBJECTIVEHepatitis C virus (HCV) is a major cause of liver disease, including liver cirrhosis andhepatocellular carcinoma. With an estimated 170 million infected individuals, HCV has amajor impact on public health. A vaccine protecting against HCV infection is not available,and current standard therapy, which is pegylated interferon- combined with ribavirin, ischaracterized by limited efficacy, high costs, and substantial side effects. As a consequence,the number of patients presenting with the long-term sequelae of chronic hepatitis C,including hepatocellular carcinoma (HCC), is expected to increase further over the next 20years. So, more effective therapies and prophylactic measurements are urgently needed forHCV.HCV is an enveloped single-stranded RNA virus of positive polarity that is a memberof the genus Hepacivirus within the family Flaviviridae. It is composed of a 5'-non-codingregion (NCR), which includes an internal ribosome entry site (IRES), an open readingframe that encodes structural and non-structural proteins, and a 3'-NCR. The structuralproteins, which form the viral particle, include the core protein and the envelopeglycoproteins E1 and E2. The non-structural proteins include the p7 ion channel, the NS2-3protease, the NS3 serine protease and RNA helicase, the NS4A polypeptide, the NS4B andNS5A proteins and the NS5B RNA-dependent RNA polymerase (RdRp).Viral entry is the first step of virus-host cell interactions leading to productive infection. HCV entry is believed to be a highly orchestrated process involving several hostcell factors including SR-BI, CD81, CLDN1 and OCLN, thereby offering multiple noveltargets for antiviral therapy. Among the host entry factors, tight junction protein CLDN1 isa promising antiviral target since it is essential for HCV entry and to date there is noevidence for CLDN1-independent HCV entry. Furthermore, CLDN1 has been suggested toplay an important role in HCV cell-cell transmission.Viruses can disseminate within a host by two mechanisms: release of cell-free virionsor direct passage between infected and uninfected cells. In general, direct cell-cell transferis considered more rapid and efficient than cell-free spread because it obviates rate-limitingearly steps in the virus life cycle, such as virion attachment. Recent developments haveallowed HCV to be propagated in cell culture [cell culture-grown hepatitis C virus(HCVcc)], allowing studies on viral transmission. HCV infection of hepatoma cells resultsin focal areas of infection that are potentiated by cell-cell contact, and this suggestslocalized transmission between adjacent cells. Recently, it has been demonstrated that HCVcan be transmited in vitro by at least two routes, cell-free virus infection and direct transferbetween cells, with the latter offering a novel route for evading neutralizing Abs. And it wasindicated that HCV cell-cell transmission is dependent on CLDN1 expression andCD81-independent routes of cell-cell transmission exist.METHODSHCVcc was established as a model in vitro. Anti-CLDN1 antibody monoclonal andpolyclonal antibodies were produced by genetic immunization. Anti-CLDN1 mAb wasused to prevent HCV infection in HCV cell culture. Inhibition of HCV spread by thepolyclonal antibody against claudin-1 and anti-HCV sera from HCV patients was assessedby the established HCV spread assay.RESULTSWe successfully produced anti-CLDN1 polyclonal and monoclonal antibodies. Anti-CLDN1 mAb bound to the extracellular loops of human CLDN1 expressed on the cellsurface with high affinity and showed no toxicity to hepatoma cells (Huh7.5.1) and primaryhepatocytes. In vitro, it inhibited HCV infection in a dose dependent manner and waseffective to HCV infection of several genotypes. Our data showed that anti-CLDN1antibody was promising to inhibit HCV spread and disemination.CONCLUSIONAntibody against CLDN1 can efficiently inhibit HCV entry and viral spread in vitro. Itis indicated that Abs against HCV receptors, especially anti-CLDN1 Abs, may constitute anovel antiviral approach to prevent HCV infection and might restrain virus spread inchronically infected patients.