Experimental duck hepatitis B virus infection: Pathology and evolution of hepatic and extrahepatic infection

Abstract

Seventy, 1‐day‐old ducklings inoculated intraperitoneally with duck hepatitis B virus and 30 controls have been studied over a 2‐year period. Infection with duck hepatitis B virus occurred in all inoculated ducks, although this was not associated with clinical morbidity. Duck hepatitis B virus DNA was first detected in liver on Day 3, in pancreatic acinar cells on Day 4, serum on Day 6, splenic red and white pulp on Day 7 and in the renal glomurulus on Day 14, using a combination of dot, Southern blot and in situ hybridization techniques. Peak levels of circulating virus, as determined by DNA polymerase levels, occurred 1 to 4 weeks postinoculation. Mild degrees of portal inflammation were seen in sections of liver tissue in both infected and control ducks. However, moderately severe inflammatory changes were present in 8 of 22 infected birds compared with 0 of 18 controls (p < 0.025). Appearance of this inflammatory infiltrate 6 weeks postinoculation coincided with a decrease in levels of duck hepatitis B virus DNA in hepatocytes and within the pancreatic acinar cells. At the same time, duck hepatitis B virus DNA became increasingly localized to the splenic germinal centers, and viral DNA was first detected in pancreatic islet cells. No histological changes accompanied the extra‐hepatic tissue infection. The sequence and significance of duck hepatitis B virus infection in liver and extra‐hepatic tissues is discussed in relation to the pathogenesis of hepatitis B virus infection in man. Copyright © 1988 American Association for the Study of Liver Diseases