[Establishment of an in vivo model for duck hepatitis B virus infection using Hubei duckling]

To develop a standard duck hepatitis B virus (DHBV) animal model using a local Hubei species of duck, Ma Ya, and use it as an in vivo experimental system to study antiviral strategies against hepatitis B.

Two-day-old Ma Ya ducklings were experimentally infected via intraperitoneal injection with the DHBV inocula which was collected from the transfected culture supernatant of 1.5-fold-overlength genome recombinant plasmid. Blood samples were taken twice or thrice a week during post-inoculation for 50 days. Viremia was quantified by serum real-time PCR to show the peak. Antiviral treatment of the DHBV-infected ducklings was started 3 d post-inoculation. The animals received oral administration of lamivudine (3TC) at a dose of 25 mg/kg/d for 5 d, followed by a maintenance therapy thrice weekly for 3 more weeks. Serum was quantified to show the viremia peak and liver biopsy specimens were analysed by Southern blotting and in-situ hybridization at the end of antiviral drug treatment.

The experimental infection rate of 2-day-old ducklings was 87.5%. Viremia started to be detectable on day 7 and reached a peak on day 11 post-inoculation, followed by a decrease and fluctuations. Four weeks of oral administration of 3TC led to a significant decrease in viremia peak during. This effect was not sustained, as a rebound in viremia was observed after drug withdrawal. Similarly, the analysis of liver biopsies at the end of 3TC treatment showed a marked decrease in DHBV DNA. However, after drug withdrawal a rebound of intrahepatic DHBV DNA was observed in duck livers.

The Hubei duck model with experimental DHBV infection of transfected supernatant is more suitable for the hepadnavirus biologic research due to its stability and practicability.