New hepatitis B virus data have been reported by H.F. Wang and co-authors
2009 JUL 13 - (NewsRx.com) -- According to recent research published in the Journal of Virology, "Viruses utilize host factors in many steps of their life cycles. Yet, little is known about host factors that contribute to the life cycle of hepatitis B virus (HBV), which replicates its genome by reverse transcription." "To identify host factors that contribute to viral reverse transcription, we sought to identify cellular proteins that interact with HBV polymerase (Pol) by using affinity purification coupled with mass spectrometry. One of the HBV Pol-interacting host factors identified was DDX3 DEAD-box RNA helicase, which unwinds RNA in an ATPase-dependent manner. Recently, it was shown that DDX3 is essential for both human immunodeficiency virus and hepatitis C virus infection. In contrast, we found that the ectopic expression of DDX3 led to significantly reduced viral DNA synthesis. The DDX3-mediated inhibition of viral DNA synthesis did not affect RNA encapsidation, a step prior to reverse transcription, and indicated that DDX3 inhibits HBV reverse transcription. Mutational analysis revealed that mutant DDX3 with an inactive ATPase motif, but not that with an inactive RNA helicase motif, failed to inhibit viral DNA synthesis. Our interpretation is that DDX3 inhibits viral DNA synthesis at a step following ATP hydrolysis but prior to RNA unwinding. Finally, OptiPrep density gradient analysis revealed that DDX3 was incorporated into nucleocapsids, suggesting that DDX3 inhibits viral reverse transcription following nucleocapsid assembly," wrote H.F. Wang and colleagues. The researchers concluded: "Thus, DDX3 represents a novel host restriction factor that limits HBV infection." Wang and colleagues published their study in the Journal of Virology (DDX3 DEAD-Box RNA Helicase Inhibits Hepatitis B Virus Reverse Transcription by Incorporation into Nucleocapsids. Journal of Virology, 2009;83(11):5815-5824). For additional information, contact W.S. Ryu, 134 Shinchondong, Seoul 120749, South Korea. The publisher's contact information for the Journal of Virology is: American Society Microbiology, 1752 N St. NW, Washington, DC 20036-2904, USA. Keywords: South Korea, Seoul, AIDS, ATPase, Acquired Immune Deficiency Syndrome, Enzyme Research, Gastroenterology, HBV, HCV, HIV, Helicase, Hepatitis B Virus, Hepatitis C Virus, Hepatology, Human Immunodeficiency Virus, Immunology, Infectious Disease, Mass Spectrometry, Nucleocapsid, Polymerase, Sexually Transmitted Disease, Viral Research, Virology. This article was prepared by Hepatitis Weekly editors from staff and other reports. Copyright 2009, Hepatitis Weekly via NewsRx.com.
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