Characteristics of woodchuck hepatitis X-antigen in the livers and sera from infected animals.

This study tests the hypothesis that woodchuck hepatitis virus encoded X-antigen expression correlates with viral replication, with hepatitis, or with both. Paired liver and serum samples from each of 55 infected woodchucks were used. Seven of 8 carriers with high levels of viral DNA in serum also had X-antigen in serum. In contrast, the frequency of X-antigen in serum was low among infected woodchucks that did not have viral surface antigen in the serum. Statistical analysis showed a significant relationship between X-antigen in serum and markers of viral replication. Woodchuck hepatitis X-antigen (WHxAg) expression in liver but not serum of carriers closely correlated with the presence of hepatitis. The finding of X-antigen in the liver of infected animals with hepatitis that cleared the virus surface antigen from serum also suggests that X-antigen is associated with ongoing hepatitis. Hence, the persistence of WHxAg in serum may signal continuing viral replication and, in liver, may contribute to the pathogenesis of chronic infection.