Occult hepatitis B: Evolving challenges and new perspectives

We read with great interest the article, “efficacy of hepatitis B vaccine in those who lost hepatitis B surface antigen during follow-up” by Taheri et al. published in Hepatitis Monthly (1). In this article, the authors assessed the efficacy of HBV vaccine in those who lost their HBsAg without seroconverssion to anti-HBs antibody with no detectable anti-HBs antibody and HBV DNA in their sera. They reported that nearly 24% of chronic HBsAg-positive subjects who lost their HBsAg responded to HBV vaccine and the remaining cases need to be followed for occult HBV infection (OBI). By definition, OBI is the presence of HBV DNA in the liver tissue in HBsAg-negative individuals. In some cases, HBV DNA can be found in serum. OBI is mainly related to a strong suppression of viral activity in which host immune response and epigenetic factors play major role. As a consequence of this viral suppression, the amount of circulating HBV DNA is very low (usually < 200 IU/mL) or even undetectable in OBI cases, so the diagnosis of this condition requires a very sensitive HBV DNA PCR assay with a detection limit of < 10 copies c 2011 Kowsar M.P.Co. All rights reserved. Please cite this paper as: Akarsu M, Kantar FU, Sayiner AA. Occult hepatitis B: Evolving challenges and new perspectives. Hepat Mon. 2011;11(6):475-6.