Pathology of hepatitis A infection in the owl monkey (Aotus trivirgatus).

Sequential liver biopsies of owl monkeys that had been experimentally infected with one of two strains of hepatitis A virus (HM-175 or PA-33) were examined for histopathologic alterations. Preinoculation biopsies were normal with only occasional minimal mononuclear cell infiltrates in portal tracts and hepatic lobular parenchyma. Histopathologic features that were present in biopsies taken during the period of elevated serum alanine aminotransferase activity (16-43 days after the intravenous inoculation of virus) included infiltration of predominantly mononuclear inflammatory cells into portal tracts and surrounding parenchyma, degeneration and necrosis of hepatocytes, and hypertrophy of Kupffer cells. Changes were similar in monkeys infected with either HM-175 or PA-33 virus strains. Convalescent biopsies (147-186 days after inoculation) showed resolving lesions with mild portal inflammation and occasional focal collections of inflammatory cells in the parenchyma. These histologic changes are similar to those associated with hepatitis A infection in man, chimpanzees, and several species of marmosets, and support the further use of the owl monkey as a model of human hepatitis A.