The narrow host range and the lack of a tissue culture system for hepatis B virus replication hampered progress in studying viral gene expression and replication. Recently, three HBV related viruses named woodchuck hepatitis virus(WHV), ground
squirrel
hepatitis virus (GSHV), and duck hepatitis B virus(DHBV) have been found. These viruses infecting nonprimates have many features of HBV, In 1988, a new hepadna virus with many of the unique characteristics of HBV has been found in Manchurian
Chipmunks
inhabiting Korea.
The aim of this study was to evaluate the pathogenesis of this new virus. Total 82 chipmunks including 14 animals with HBsAg-positive sera(group I), 12 HBsAg-negative animals(group II), 43 animals incculated with pooled HBsAg-positive chipmunk
sera(group III) and 13 animals inoculated with pooled HBsAg-negative sera(group IV) were included. The histological examination and the immunohistochemical staining of HBsAg and HBcAg were performed in the liver tissues from the chipmunks.
Histologic examination of liver tissues of group I and II revealed no evidence of liver cell necrosis, infiltration of inflammatory cells or fibrosis. Histologic examination of liver tissues extracted from group III revealed pathologic findings
of
acute
hepatitis in 12 animals(28%), chronic hepatitis in 18 animals(42%). In constrast, chipmunks of group IV showed no evidence of liver diseases. HBsAg was not detected in any of the liver tissues by immunohistochemistry staining. However, by
immunohistochemistry staining HBcAg was detected in liver tissues from 3 of 14 chipmunks921%) in group I, none in group II, 23 of 43 chipmunks (53%) in group III and none in group IV. The results showed that natural infection of chipmunk
hepatitis
virus
is usually not associated with liver diseases, but experimental infections by inoculation of the virus frequently lead to the viral replication in the liver tissues and the occurence of significant acute and chronic liver diseases.
In conclusion, this new hepadna virus found in Manchurian chipmunks would be a useful model for the study of viral replication, gene expression and hepatic pathogenesis. (Korean J Gastroenterol 1994 ; 26 : 925-930)
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