Development of a cell-based assay to identify hepatitis B virus entry inhibitors targeting the sodium taurocholate cotransporting polypeptide

Abstract

// Kei Miyakawa 1 , Satoko Matsunaga 1 , Yutaro Yamaoka 1, 2 , Mina Dairaku 1 , Kento Fukano 3 , Hirokazu Kimura 4 , Tomoyuki Chimuro 2 , Hironori Nishitsuji 5 , Koichi Watashi 3 , Kunitada Shimotohno 5 , Takaji Wakita 3 and Akihide Ryo 1 1 Department of Microbiology, Yokohama City University School of Medicine, Kanagawa 236-0004, Japan 2 Isehara Research Laboratory, Technology and Development Division, Kanto Chemical Co., Inc., Kanagawa 259-1146, Japan 3 Department of Virology II, National Institute of Infectious Diseases, Tokyo 162-8640, Japan 4 School of Medical Technology, Faculty of Health Sciences, Gunma Paz University, Gunma 370-0006, Japan 5 Research Center for Hepatitis and Immunology, National Center for Global Health and Medicine, Chiba 272-8516, Japan Correspondence to: Akihide Ryo, email: aryo@yokohama-cu.ac.jp Keywords: HBV-permissive cell; anti-NTCP monoclonal antibody; glabridin; innate immune signaling; ISG Received: January 06, 2018      Accepted: April 24, 2018      Published: May 04, 2018 ABSTRACT Sodium taurocholate cotransporting polypeptide (NTCP) is a major entry receptor of hepatitis B virus (HBV) and one of the most attractive targets for anti-HBV drugs. We developed a cell-mediated drug screening method to monitor NTCP expression on the cell surface by generating a HepG2 cell line with tetracycline-inducible expression of NTCP and a monoclonal antibody that specifically detects cell-surface NTCP. Using this system, we screened a small molecule library for compounds that protected against HBV infection by targeting NTCP. We found that glabridin, a licorice-derived isoflavane, could suppress viral infection by inducing caveolar endocytosis of cell-surface NTCP with an IC 50 of ~40 μM. We also found that glabridin could attenuate the inhibitory effect of taurocholate on type I interferon signaling by depleting the level of cell-surface NTCP. These results demonstrate that our screening system could be a powerful tool for discovering drugs targeting HBV entry.