Two distinct types of hepatitis in experimental hepatitis B virus infection.

The course of experimental hepatitis B in chimpanzees was studied, and two biochemically, serologically, and histopathologically distinctive types were identified. The first type was self-limiting, rapidly resolving hepatitis with spiking and short-term elevation of SGPT starting at around 5 weeks after the appearance of HBs antigenemia. The second type was smoldering and persistent hepatitis with low-plateau-forming persistent transanimase abnormality developing around 10 weeks after the appearance of HBsAg. Anti-HBc became positive before the transaminase elevation in the second type, while in the first type it became positive after the SGPT elevation. Histologically, the second type was characterized by marked infiltration of lymphoid cells in portal areas with lymphoid follicles. This was seen even before the histologic manifestations of liver cell injury and the elevation of SGPT in two cases. The portal inflammatory cell infiltration became evident at 6 to 9 weeks after the HBsAg appearance and became increasingly more severe thereafter. The intralobular changes remained mild, with rare liver cell necroses. Chronic hepatitis developed subsequently in two cases. In the first type, the portal changes developed almost simultaneously with intralobular changes and were not prominent. In contrast to the second type, the intralobular changes with multiple liver cell necrosis were more severe.