The pathology of viral hepatitis types A and B in chimpanzees. A comparison.

The histologic manifestations in the livers of chimpanzees inoculated with hepatitis A and B virus were compared with each other and correlated with biochemical, serologic, and virologic observations. Both types of hepatitis reveal alterations similar to those seen in human hepatitis, but the lesions--particularly the hepatocellular necrosis--are far milder. Hepatitis Type A in chimpanzees is a disease of short incubation period and duration. The hepatocytic alterations are mainly restricted to the periportal areas, and the parenchymal changes are less severe than the portal inflammation. The lesions correlated well with biochemical changes, the presence of virus in the liver, and its shedding in the stool. In contrast, experimental Type B hepatitis has a long incubation period and longer duration, involves the entire lobular parenchyma, and is, if anything, more severe in the lobular centers while portal inflammation is less conspicuous. Biochemical alterations and presence of virus in the liver correlate with these lesions, and the antibody response is similar to that seen in man. The chimpanzee is a useful model for studying the pathogenesis of viral hepatitis; additional study of serial morphologic events may contribute to our understanding of the clinical differences between hepatitis Type A and Type B.