Abstract from Fourth National Congress of Virology with International Participation /Days of Virology in Bulgaria Sofia, May 18th - 20th, 2016

Denitsa Tsaneva-Damyanova, Liliya Ivanova Ivanova

Department of Microbiology and Virology, Medical University, Varna, Medical laboratory”Status”, Varna

Department of Microbiology and Virology, Medical University, Varna, University Hospital “St.Marina”, Laboratory of Clinical Microbiology and Virology, Varna, Bulgaria

Goals: Occult hepatitis B infection (OBI) is a new challenge in virology and a clinically relevant topic. In 2008, in Taormina (Italy), the European Association for the study of the liver (EASL) defined OBI as the presence of hepatitis B virus (HBV) DNA in the liver (with detectable or undetectable HBV DNA in the serum) of individuals testing hepatitis B surface antigen (HBsAg) negative by currently available assays. As a general rule the patients with OBI show anti- HBc total positive and /or anti-HBs positive result, when serologically tested in the absence of HBsAg -seropositive-OBI. About 20 % of the patients with OBI are with seronegative- OBI- anti HBc total and anti- HBs negative. When detectable, the amount of HBV DNA in the serum is usually very low (< 200 IU/ml). The present study assessed the presence of HBV-DNA in serum samples of anti- HBc total positive patients with data of liver dysfunction as anti- HBs positive ones were excluded from the discussion.

Methods: In our research we have evaluated 55 patients from University Hospital “St.Marina” Varna, Bulgaria with clinical data of liver dysfunction, elevated liver enzymes (including aspartate aminotransferase (AST) and alanine aminotransferase (ALT)), HBsAg (-), anti HBc total (+), some of them under immunosuppression. All of the patients were referred to the Laboratory of Clinical Microbiology and Virology at the University Hospital and investigated for HBsAg, anti-HBc total by ELISA, using the commercially available tests. PCR for quantitative detection of HBV-DNA was performed at Laboratory of Viral Hepatitis, National Center of Infectious and Parasitic diseases, Sofia, Bulgaria, with detection limits less than 10 copies of HBV DNA per reaction.DNA is extracted from 1 ml of serum using commercially available Abbot test kit.

Results: From all of the 55 investigated patients with liver dysfunction, 7 (12,7%) are positive for HBV DNA, as it is the only reliable diagnostic marker and defined as occult HBV carriers. Conclusion:The recent study therewithal many others, that have been carried out, on OBI prevalence in different area of the world, leads to the conclusion that prevalence of OBI seem to be higher among subjects at high risk of HBV infection and with liver disease than among individuals at low risk of infection and without liver disease. According to us, OBI should be considered invariably in the presence of clinical and laboratory evidence of liver dysfunction