Partial analysis of hepatitis B virus DNA from hepatocellular carcinoma showing negative hepatitis B virus surface antigen: an analysis of two Japanese cases.

It has been reported that hepatitis B virus (HBV) DNA is detected in serum and/or liver in patients with hepatocellular carcinoma (HCC) without HBsAg. To adress this issue, we analyzed HBV genome in 2 HCC cases without HBsAg. The DNA from serum from patients with HCC was amplified with a nested PCR, and 'a' determinant of S region, core promoter region and precore region were sequenced. The first case, a 50 years-old male, was negative for HBsAg and HBeAg, and positive for anti-HBs, anti-HBe and anti-HBc. Viral load of HBV in serum was 4.0 log genome equivalent/ml by TMA assay, and was 1.1 X 105 copy/ml by real-time PCR system. A nucleotide analysis of the common 'a' determinant of S gene showed that the 5 first amino acids of 'a' determinant, CTIPA, were changed to CKTCTTPA. The second case, a 76 years-old male, was positive for anti-HBe, but negative for HBsAg, anti-HBs, HBeAg and anti-HBc. No missense or nonsense mutations were seen in 'a' determinant of S region. Viral load of serum HBV was < 3.7 log genome equivalent/ml by TMA assay, but was 2.4X103 copy/ml by real-time PCR system. The results of the present study suggest that the mechanisms of HBsAg loss are diverse among HCC patients without HBsAg, and that an analysis of HBV genome is a useful tool to dissolve molecular mechanisms losing HBs antigenicity.