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Hepatitis B virus hijacks CTHRC1 to evade host immunity and maintain replication Free
Lan Bai, Wei Zhang, Li Tan, Hongchuan Yang, Maolin Ge, Chengliang Zhu, Rui Zhang, Yanhua Cao, Junbo Chen, Zhen Luo, Wenzhe Ho, Fang Liu, Kailang Wu*, and Jianguo Wu*
State Key Laboratory of Virology and College of Life Sciences, Wuhan University, Wuhan 430072, China *Correspondence to:Jianguo Wu, E-mail: jwu@whu.edu.cn; Kailang Wu, E-mail: wukailang@whu.edu.cn
J Mol Cell Biol, Volume 7, Issue 6, December 2015, 543-556,  https://doi.org/10.1093/jmcb/mjv048
Keyword: hepatitis B virus, collagen triple helix repeat containing 1 (CTHRC1), immune response, immune evasion, PKC/JNK/ERK/c-Jun cascade, IFN/JAK/STAT pathway

Hepatitis B virus (HBV) infection causes acute and chronic liver diseases, but is not directly cytopathic. Liver injury results from repeated attempts of the cellular immune response system to control the viral infection. Here, we investigate the roles of cellular factors and signaling pathways involved in the regulation of HBV replication to reveal the mechanism underlying HBV infection and pathogenesis. We show that collagen triple helix repeat containing 1 (CTHRC1) expression is elevated in HBV-infected patients and in HBV-transfected cells through epigenetic modification and transcriptional regulation. CTHRC1 facilitates HBV replication in cultured cells and BALB/c mice by activating the PKCα/ERK/JNK/c-Jun cascade to repress the IFN/JAK/STAT pathway. HBV-activated CTHRC1 downregulates the activity of type I interferon (IFN), the production of IFN-stimulated genes (ISGs), and the phosphorylation of signal transducer and activator of transcription 1/2 (STAT1/2), whereas it upregulates the phosphorylation and ubiquitination of type I IFN receptors (IFNARα/β). Thus, our results show that HBV uses a novel mechanism to hijack cellular factors and signal cascades in order to evade host antiviral immunity and maintain persistent infection. We also demonstrate that CTHRC1 has a novel role in viral infection.