Acute liver injury following infection with a cytopathic strain of duck hepatitis B virus.

A variant avian hepadnavirus that has been shown to destroy hepatocytes in vitro was found to be cytopathic in vivo. A single amino acid change of glycine to glutamic acid at position 133 (G133E) in the preS protein of duck hepatitis B virus (DHBV) caused an increase in the intranuclear pool of viral covalently closed circular DNA (cccDNA), resulting in a transient elevation of viral replication and eventual hepatocyte destruction. In vivo viral infection with the G133E virus was compared with infection with wild-type virus over a 72-day period. Birds were inoculated with virus at day 2 post-hatch to ensure a high percentage of infected hepatocytes and potential persistence of virus. Birds infected with the G133E virus had increased periportal cellular proliferation and numerous lysed apoptotic hepatocytes following 100% infection of hepatocytes. The liver damage within G133E virus-infected birds subsided over time, resulting in mild chronic hepatitis that was similar to that observed within wild-type virus-infected birds. The subsidence of liver damage in G133E virus-infected birds coincided with a reduction of viral cccDNA to wild-type virus levels in the liver. Our study indicates that maintenance of wild-type levels of viral cccDNA promotes persistence of virus infection by establishing a noncytopathic infection.