Prevalence and molecular analysis of occult hepatitis B virus infection isolated in a sample of cryptogenic cirrhosis patients in Iran

الملخص EN

The aims of this study are to investigate the prevalence of occult hepatitis B virus infection among patients with cryptogenic cirrhosis and to analyze the relationship between surface protein variability and occult hepatitis B virus infection, which may be related to the pathogenesis of occult hepatitis B virus infection in cryptogenic cirrhosis.

Occult hepatitis B virus infection is a wellrecognized clinical entity characterized by the detection of hepatitis B virus DNA in serum and/or liver in the absence of detectable hepatitis B virus surface antigen, with or without any serological markers of a past infection.

Methods: Sera from patients with cryptogenic chronic liver disease were tested for hepatitis B virus DNA using both real-time and nested PCR.

In the detected hepatitis B virus DNA samples, the surface gene was analyzed for mutations.

Results: Hepatitis B virus DNA was detected in 38% of patients, all of whom had a viral load below 10,000 copies/mL.

All hepatitis B virus belonged to genotype D.

There were no significant associations between occult hepatitis B virus infection status and age, gender, ALT/AST levels, viral load or serologic markers of previous hepatitis B virus infection.

There were 14 mutations found in 5 patients; 6 were in the major hydrophilic region, of which 4 were Y134F assigning for the "a" determinant region.

All patients who acquired Y134F contained S207R (within HLA-A2-restricted CTL epitope) as a combination.

Conclusion: Hepatitis B virus surface antigen variants may arise as a result of natural selection to evade the immune surveillance of the infected host, and subsequently may go undetected by conventional hepatitis B virus surface antigen screening tests.

Etiological diagnosis of cryptogenic cirrhosis is significantly underestimated with current serology testing methods alone.