HUMAN HEPATITIS-B VIRUS AND HEPATOCELLULAR-CARCINOMA .2. EXPERIMENTALINDUCTION OF HEPATOCELLULAR-CARCINOMA IN TREE SHREWS EXPOSED TO HEPATITIS-B VIRUS AND AFLATOXIN-B1

On the basis of the successful establishment of an animal model in tre e shrews experimentally infected with human hepatitis B virus (HBV), a study on the hepatocarcinogenic effects of HBV and/or aflatoxin B1 (A FB1) was conducted. The results showed that the incidence of hepatocel lular carcinoma (HCC) was significantly higher in the animals both inf ected with HBV and exposed to AFB1 (52.94%) than in those solely infec ted with HBV (11.11%) or exposed to AFB1 (12.50%). No HCC of precancer ous lesions were found in the controls that were neither HBV-infected nor AFB1-exposed. Precancerous lesions, including liver cell dysplasia and enzyme-altered hyperplastic hepatocyte foci, were observed before the occurrence of HCC, and the frequency of their appearance correlat ed well with the incidence of HCC. HBV DNA and the protein it encodes were detected in the cancer cells and/or the surrounding hepatocytes. Integration of HBV DNA inot the host liver genome was found during hep atocarcinogenesis among the animals infected by HBV. These results sug gest that exposure to HBV and AFB1 may play a synergistic role in the development of HCC, and support the viewpoint of an aetiological relat ionship between HBV and HCC.