Morphology and immunohistochemistry of experimental and human non-A, non-B hepatitis

The diagnosis of non-A, non-B hepatitis (NANBH) presently depends on the exclusion of hepatitis A, B and other causes of hepatitis, because no specific tests are available for diagnosis. Different approaches were used in order to detect NANBH infection in human and chimpanzee tissue. Endogenous interferon production was not detected in the weekly serum samples of 6 chimpanzees inoculated with a human agent of NANBH in contrast to the 5 HBV-infected animals. An antibody raised against a glycoprotein (GP77) associated with NANBH reacted immunohistochemically with liver biopsies obtained from NANBH-infected chimpanzees and with 11 out of 14 human liver biopsies from patients with NANBH. Two out of 12 human biopsies taken from patients with other liver diseases were positive. Diffuse reaction was noted in the cytoplasm of hepatocytes in chimpanzees. Three reaction patterns--diffuse, submembranous and perinuclear--were observed in human liver biopsies. A 35S radiolabeled DNA-probe of 780 base pairs--specific activity 5.4 x 10(4) cmp/micrograms DNA--isolated from NANBH-infected chimpanzees has been shown to hybridize in situ with liver sections from NANBH-infected chimpanzees. Data suggest that immunohistochemical and in situ hybridization methods can be successfully used for detection of NANBH infection in the liver of humans and chimpanzees.