[Dynamic detection of duck hepatitis B virus cccDNA in serum of ducks with liver injury].

OBJECTIVE: To confirm whether DHBV cccDNA could be detected in serum of DHBV-infected ducks after liver injury.

METHODS: Twenty four ducks with persistent DHBV infection were divided into 4 groups with the following treatments: A, D-galactosamine (D-GalN, 2.2 g/kg) and lipopolysaccharide (LPS, 100 µg/kg); B, 10 mg/kg of carbon tetrachloride (CCl4) every 12 h twice following D-GalN and LPS; C, 15 mg/kg of CCl4 every 12 h twice following D-GalN and LPS; D, normal saline as normal control (NC). At 0 h, 24 h, 36 h and 48 h post-treatment, sera were collected from each duck for determination of serum DHBV load, DHBV cccDNA and alanine aminotransferase (ALT). And ducks were eventually sacrificed to obtain liver specimens for pathological assessment of liver lesions and determination of intrahepatic total DHBV DNA and DHBV cccDNA.

RESULTS: (1) No obvious pathological change was observed in the liver of ducks from NC group while the indices of liver injury were significantly different between Groups A, B and C; (2) DHBV cccDNA was undetectable in the sera of ducks from NC and A group at all time points. In contrast, DHBV cccDNA, varying from 3.17 × 10(3) copies/ml to 1.72 × 10(4) copies/ml, was detected in the sera of 2 ducks from Group B and 3 ducks from Group C at 36 h post-treatment. The occurrence of DHBV cccDNA in serum was significantly correlated with the degree of liver injury while no significant association with serum ALT level and DHBV load as well as with the level of intrahepatic total DHBV DNA and DHBV cccDNA was observed.

CONCLUSION: DHBV cccDNA may be detected in the serum when the liver of duck is seriously damaged. The incidence of DHBV cccDNA occurrence in the serum is significantly associated with the severity of liver injury.