Brief Article
Copyright ©2012 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Jun 14, 2012; 18(22): 2850-2858
Published online Jun 14, 2012. doi: 10.3748/wjg.v18.i22.2850
DNA-dependent activator of interferon-regulatory factors inhibits hepatitis B virus replication
Qi-Ying Chen, Ying-Hui Liu, Jian-Hua Li, Ze-Kun Wang, Jiang-Xia Liu, Zheng-Hong Yuan
Qi-Ying Chen, Jian-Hua Li, Jiang-Xia Liu, Zheng-Hong Yuan, Key Laboratory of Medical Molecular Virology, Ministry of Education and Ministry of Health, Shanghai Medical College, Fudan University, Shanghai 200032, China
Ying-Hui Liu, Ze-Kun Wang, Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
Author contributions: Chen QY, Liu YH contributed equally to this work; Chen QY, Liu YH participated in the design of study, carried out the experiments and drafted the manuscript; Li JH participated in the design of study; Wang ZK and Liu JX performed the statistical analysis; and Yuan ZH designed the research and reviewed the drafts.
Supported by Grants of The Chinese State Basic Research, No. 2009CB522504; and National Mega Projects for Infectious Diseases, No. 2008ZX10203
Correspondence to: Zheng-Hong Yuan, MD, Professor, Key Laboratory of Medical Molecular Virology, Ministry of Education and Ministry of Health, Shanghai Medical College, Fudan University, 138 Yi Xue Yuan Road, Shanghai 200032, China. zhyuan@shaphc.org
Telephone: +86-21-64161928 Fax: +86-21-64227201
Received: June 7, 2011
Revised: September 13, 2011
Accepted: March 10, 2012
Published online: June 14, 2012
Abstract

AIM: To investigate whether DNA-dependent activator of interferon-regulatory factors (DAI) inhibits hepatitis B virus (HBV) replication and what the mechanism is.

METHODS: After the human hepatoma cell line Huh7 was cotransfected with DAI and HBV expressing plasmid, viral protein (HBV surface antigen and HBV e antigen) secretion was detected by enzyme-linked immunosorbent assay, and HBV RNA was analyzed by real-time polymerase chain reaction and Northern blotting, and viral DNA replicative intermediates were examined by Southern blotting. Interferon regulatory factor 3 (IRF3) phosphorylation and nuclear translocation were analyzed via Western blotting and immunofluorescence staining respectively. Nuclear factor-κB (NF-κB) activity induced by DAI was detected by immunofluorescence staining of P65 and dual luciferase reporter assay. Transwell co-culture experiment was performed in order to investigate whether the antiviral effects of DAI were dependent on the secreted cytokines.

RESULTS: Viral protein secretion was significantly reduced by 57% (P < 0.05), and the level of total HBV RNA was reduced by 67% (P < 0.05). The viral core particle-associated DNA was also dramatically down-regulated in DAI-expressing Huh7 cells. Analysis of involved signaling pathways revealed that activation of NF-κB signaling was essential for DAI to elicit antiviral response in Huh7 cells. When the NF-κB signaling pathway was blocked by a NF-κB signaling suppressor (IκBα-SR), the anti-HBV activity of DAI was remarkably abrogated. The inhibitory effect of DAI was independent of IRF3 signaling and secreted cytokines.

CONCLUSION: This study demonstrates that DAI can inhibit HBV replication and the inhibitory effect is associated with activation of NF-κB but independent of IRF3 and secreted cytokines.

Keywords: DNA-dependent activator of interferon regulatory factor; Antiviral activity; Hepatitis B virus; Nuclear factor-κB; Interferon regulatory factor-3