Discovery of Anti–Claudin-1 Antibodies as Candidate Therapeutics against Hepatitis C Virus

Abstract

Claudin-1 (CLDN1), a known host factor for hepatitis C virus (HCV) entry and cell-to-cell transmission, is a target molecule for inhibiting HCV infection. We previously developed four clones of mouse anti-CLDN1 monoclonal antibody (mAb) that prevented HCV infection in vitro. Two of these mAbs showed the highest antiviral activity. Here, we optimized the anti-CLDN1 mAbs as candidates for therapeutics by protein engineering. Although Fab fragments of the mAbs prevented in vitro HCV infection, their inhibitory effects were much weaker than those of the whole mAbs. In contrast, human chimeric IgG1 mAbs generated by grafting the variable domains of the mouse mAb light and heavy chains inhibited in vitro HCV infection as efficiently as the parental mouse mAbs. However, the chimeric IgG1 mAbs activated Fcg receptor, suggesting that cytotoxicity against mAb-bound CLDN1-expressing cells occurred through the induction of antibodydependent cellular cytotoxicity (ADCC). To avoid ADCC-induced side effects, we prepared human chimeric IgG4 mAbs. The chimeric IgG4 mAbs did not activate Fcg receptor or induce ADCC, but they prevented in vitro HCV infection as efficiently as did the parental mouse mAbs. These findings indicate that the IgG4 form of human chimeric anti-CLDN1 mAb may be a candidate molecule for clinically applicable HCV therapy.

Novel human anti-claudin 1 mAbs inhibit hepatitis C virus infection and may synergize with anti-SRB1 mAb

“…The ability of anti-CLDN-1 human mAbs to inhibit infection by different HCV isolates was not unexpected and was in line with previous observations made with rat and mouse anti-CLDN-1 antibodies (Fofana et al, 2010;Fukasawa et al, 2015;Mailly et al, 2015;Yamashita et al, 2015). Most importantly, mAbs B9X and D10X displayed binding affinity for cell-displayed CLDN-1 and IC 50 values comparable with the rat anti-CLDN-1 mAb OM-7D3, which was recently shown to prevent HCV infection and to clear persistent infection in a human liver-chimeric mouse model without detectable toxicity .…”

“…In particular, we previously showed that the human anti-SRB1 mAb C-1671 completely prevents infection and intrahepatic spread of multiple HCV genotypes in vivo in human liver-chimeric mice (Meuleman et al, 2012). Human mAbs against CLDN-1 and OCLN have not been reported yet, but rat, mouse and mouse/human chimeric anti-CLDN-1 antibodies were found to efficiently inhibit infection by HCV of major genotypes in cell culture (Fofana et al, 2010;Yamashita et al, 2015) and some of them eliminate chronic HCV infection without detectable toxicity when administered to human liver-chimeric mice Mailly et al, 2015).…”

Claudins in viral infection: from entry to spread

“…As such, claudins are attractive antiviral targets. Indeed, antibodies and peptides targeting CLDN1 have been shown to be highly effective against HCV [27, 30, 54, 60, 73, 85, 100]. These antibodies are thought to block formation of the nonphysiological CLDN1-CD81 co-receptor complex during HCV entry, and thus lack any obvious toxic effects for the host.…”

“…Monoclonal antibodies that target CLDN1 interfere with the formation of the co-receptor complex [54]. These antibodies pan-genotypically inhibit cell-free infection and cell-to-cell transmission of HCV in human hepatoma cells [27, 54, 100]. Strikingly, anti-CLDN1 antibodies prevent HCV infection of human liver chimeric mice [30, 60] and were even able to cure chronically HCV-infected liver chimeric mice [60] without any detectable toxicity.…”

Generation and characterization of a human–mouse chimeric antibody against the extracellular domain of claudin-1 for cancer therapy using a mouse model

“…Human-mouse chimeric antibodies were prepared as described previously [12]. Briefly, cDNA encoding the heavy-chain and light-chain variable domains of 3A2 (anti-CLDN-1) were grafted onto the pFUSE-CHIg-hG1 and pFUSE2-CLIg-hk vectors (InVivoGen, San Diego, CA), respectively.…”