DUCK HEPATITIS-B VIRUS-INFECTION, AFLATOXIN B-1 AND LIVER-CANCER IN DOMESTIC CHINESE DUCKS

The oncogenicity of Duck hepatitis B virus (DHBV) is unclear since hep atocellular carcinomas (HCCs) have been reported only in domestic duck s in Qidong, an area of China where hepatitis B virus (HBV) and aflato xin B-1 (AFB(1)) are risk factors for liver cancer in man. In order to better define the association between DHBV infection, AFB(1) and HCC we analysed a series of 16 duck liver samples collected from local far ms in Qidong. HCC was found in eight and cirrhosis in one of these sam ples. Furthermore bile duct proliferation, characteristic of AFB(1) ex posure in ducks and other animal species, was found in these ducks. In tegration of DHBV DNA into cellular DNA was observed in only one out o f four DHBV positive HCCs, indicating that viral integration is not pr erequisite for tumour development. In four remaining HCCs the polymera se chain reaction (PCR) failed to show any DHBV DNA suggesting that li ver tumours do occur in these ducks in the absence of DHBV infection. In addition, AFB(1)-DNA adducts were detected by hplc-immunoassay in o ne such DHBV-negative tumour. In summary we demonstrate that risk fact ors other than DHBV, including AFB(1) exposure, may be important in du ck liver carcinogenesis in Qidong.