Occult hepatitis B virus infection

Many studies have shown that hepatitis B virus infection may also occur in hepatitis B surface antigen-negative patients. This occult infection has be en identified both in patients with cryptogenic liver disease and in patien ts with hepatitis C virus-related chronic hepatitis, and much evidence sugg ests that it may be a risk factor of hepatocellular carcinoma development. However, several aspects of this occult infection remain unclear such as it s prevalence and the factor(s) involved in the lack of circulating hepatiti s B surface antigen. Moreover, it is uncertain whether the occult hepatitis B virus infection may contribute to chronic liver damage, considering that it is usually associated with a suppressed viral replication. Evidence and hypotheses concerning this fascinating field of bio-medical research are r eviewed.