Occult hepatitis B virus infection in Southern African blacks with hepatocellular carcinoma

Background and Aim: To ascertain the prevalence of occult hepatitis B virus (HBV) infection in southern African blacks with hepatocellular carcinoma. Results: Sera from 118 patients negative for HBV surface antigen but positive for HBV antibodies were studied. HBV-DNA was detected using a nested polymerase chain reaction (PCR) assay and confirmed by nucleotide sequencing of the surface and precore/core genes. Results: Surface gene HBV-DNA was detected in a single PCR assay in 48.4% of the patients. Positive results increased to 57.7% after two PCR assays (not significant) and 75.7% after four assays (P < 0.001). No false positive results were obtained in these assays or in the 15 control samples for which PCR assays were performed four times. Significant differences in positivity rates were not observed between patients positive for HBV core antibody alone and those positive for core and surface antibodies. The sensitivity of the PCR amplification of the precore/core gene was significantly less than that of the surface open reading frame: the yield of positive results was 23.7% after one assay, 32.2% after two assays (not significant), and 52% after four assays (P < 0.001). Combining the results of the assays of the two genes increased the yield of positive results for the first assay (by 11.9%, P = 0.015), but not the second (6.1%) or fourth assays (4.6%). Conclusion: Occult HBV infection is present in the serum of the majority of hepatocellular carcinomas in southern African blacks whose serum is negative for hepatitis B surface antigen but positive for anti-HBV core antigen. The yield of positive results increases if more than one PCR assay is performed.