Occult hepatitis B virus infection [Gizli hepatit B virüs infeksiyonu]

Abstract

For HBV infection, several distinct outcomes have been defined traditionally based on the results of serological tests for HBV antigens and the antibodies produced against them: recovery, chronic hepatitis B, 'healthy' carier, and occult hepatitis B. Occult hepatitis B has recently been identified by sensitive PCR assays that may detect low levels of HBV DNA in the serum samples and/or liver of people who are HBsAg negative. The molecular/ immunological mechanisms underlying occult hepatitis B infection remain incompletely defined and are probably multifactorial. 1- Mutation of HBV DNA in S region. 2-Integration of HBV DNA into host's chromosomes. 3- HBV infection of peripheral blood mononuclear cells (PBMC). 4- HBV containing immun complex. 5- Status of host immun responses. 6- Virus interference. 7- HBV genotype. Occult HBV infection may cause transfusion-transmitted HBV infection, and may serve as a source of infection in liver transplant recipients. Using PCR amplification, most studies demonstrated the HBV DNA genome in 22% to 87% of the patients with HBsAg-negative and HCV RNA-positive tests. Occult hepatitis B has been associated with advanced fibrosis/cirrhosis in cross-sectional studies and with poor interferon responses in HCV-infected patients. Occult hepatitis B has been reported in a high proportion of HCV-infected patients who develop hepatocellular carcinoma. HBV DNA was detected in HBsAg-negative fulminant hepatic failure in a significant proportion of cases (% 0-47). Clinicians should consider testing for occult hepatitis B in the following situations: 1- Patients with the risk factors for HBV infection in whom immunosupression is expected. 2- Patients with unexplained liver disease. 3- Patients with isolated HBcAb who are solid organ donors 4- ALT levels remain elevated in HCV-infected patients, when HCV RNA is cleared by the treatment.