Etiology of acute exacerbation in patients with severe chronic active hepatitis by in situ HBVDNA hybridization technique.

To explore etiology of acute exacerbation in severe chronic active hepatitis, in situ HBVDNA hybridization was carried out combined with detection of HBV markers in the serum and the liver as well as intrahepatic HDAg in 15 cases. Four subgroups were identified based on the etiological evidence: 1) 9 cases were still undergoing HBV active replication or reactivation with cytoplasmic and membraneous HBcAg expression, often associated with the hepatic necrosis foci; 2) 3 cases showed HBsAg or/and HBVDNA positivity despite absence of HBcAg expression, the membranous and homogeneous HBsAg expression being closely related with hepatic necrosis; 3) 2 cases were HDAg positive; 4) the remaining case exhibited no HBV infection evidence. All findings suggested that HBV active replication or reactivation was the major cause of the exacerbation in severe chronic active hepatitis. In addition, HBV superinfection accounted for over 10% of cases with acute exacerbation. Hepatitis A or C may contribute to some episodes of exacerbation.