Detection of hepatitis E virus genome and gene products in two patients with fulminant hepatitis E

Non-isotopic in situ hybridization (digoxigenin-labeled probe directed towards hepatitis E virus ORF1) and immunohistochemistry (against hepatitis E virus ORF2 and ORF3) were applied to detect hepatitis E virus genome and gene product in the liver tissue of two patients with fulminant hepatitis E seropositive for hepatitis E virus RNA. Both hepatitis E virus RNA and hepatitis E virus antigens were detected exclusively in the cytoplasm of hepatocytes and not detected in other cell types. In both patients, more than 50% of the hepatocytes were positive for both hepatitis E virus RNA and hepatitis E virus antigens, most of which showed degenerative changes. This is consistent with the histological appearance of marked loss of hepatocytes with acinar collapse. Interestingly, denaturation of the RNA before in situ hybridization was found to enhance hepatitis E virus RNA detection. We conclude that: (1) hepatitis E virus RNA and hepatitis E virus antigens can be demonstrated in the liver in hepatitis E virus-related fulminant hepatitic failure, (2) hepatitis E virus is hepatocyte-tropic within the liver, (3) cytoplasmic localization of hepatitis E virus RNA and hepatitis E virus antigens is consistent with cytoplasmic replication, and (4) the presence of degenerative changes in hepatitis E virus positive cells, together with the histological appearance of hepatocyte loss in the absence of significant inflammatory infiltrate, suggests that hepatitis E virus-related fulminant hepatitic failure is mediated by a cytopathic mechanism.