Copyright ©2007 Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Nov 21, 2007; 13(43): 5682-5686
Published online Nov 21, 2007. doi: 10.3748/wjg.v13.i43.5682
Persistent occult hepatitis B virus infection: Experimental findings and clinical implications
Patricia M Mulrooney-Cousins, Tomasz I Michalak
Patricia M Mulrooney-Cousins, Tomasz I Michalak, Molecular Virology and Hepatology Research, Division of BioMedical Science, Faculty of Medicine, Health Sciences Centre, Memorial University, St. John’s, NL A1B 3V6, Canada
Author contributions: All authors contributed equally to the work.
Supported by operating research grants from the Canadian Institutes of Health Research, Canada and the Canada Research Chair Program, and the Canada Foundation for Innovation
Correspondence to: Tomasz I Michalak, MD, PhD, Molecular Virology and Hepatology Research, Faculty of Medicine, Health Science Centre, Memorial University, 300 Prince Philip Drive, St. John’s, NL A1B 3V6, Canada. timich@mun.ca
Telephone: +1-709-7777301 Fax: +1-709-7778279
Received: July 24, 2007
Revised: September 5, 2007
Accepted: October 12, 2007
Published online: November 21, 2007

Hepatitis B virus (HBV) is a highly pathogenic virus that causes chronic liver diseases in millions of people globally. In addition to a symptomatic, serologically evident infection, occult persistent HBV carriage has been identified since nucleic acid amplification assays of enhanced sensitivity became introduced for detection of hepadnaviral genomes and their replicative intermediates. Current evidence indicates that occult HBV infection is a common and long-term consequence of resolution of acute hepatitis B. This form of residual infection is termed as secondary occult infection (SOI). The data from the woodchuck model of HBV infection indicate that exposure to small amounts of hepadnavirus can also cause primary occult infection (POI) where virus genome, but no serological makers of exposure to virus, are detectable, and the liver may not be involved. However, virus replicates at low levels in the lymphatic system in both these forms. We briefly summarize the current understanding of the nature and characteristics of occult hepadnaviral persistence as well as of its documented and expected pathological consequences.

Keywords: Hepatitis B virus, Hepadnaviruses, Woodchuck hepatitis virus, Hepadnaviral hepatitis, Occult viral persistence, Hepadnavirus lymphotropism, Primary occult infection, Secondary occult infection, Virus reactivation