PATHOLOGY OF LIVERS INFECTED WITH SILENT HEPATITIS-B VIRUS MUTANT

We have discovered that non-A, non-B, non-C, non-D, non-E (so-called t ype F) acute and chronic hepatitis is caused by a hepatitis B virus (H BV) variant with mutations in the X open reading frame. This silent HB V mutant does not induce immunoserological markers. In the present inv estigation we attempted to elucidate the putative mechanism of hepatoc ellular necrosis and expression patterns of hepatitis B surface antige n (HBsAg) and core antigen (HBcAg) in biopsied liver tissue. The subje cts consisted of 14 patients with acute hepatitis, 11 with chronic hep atitis and eight with liver cirrhosis, all of whom had been previously diagnosed as having so-called hepatitis F. Nine of the 14, 10 of the 11 and all eight, respectively, of the above patients exhibited signif icant positive immunostaining for HBsAg within their hepatocellular cy toplasm, diffusely or focally. HBcAg stained in a few hepatocellular n uclei in 24.2% of the patients. Histological features were characteriz ed by necroinflammation, indicating immune-mediated hepatocellular nec rosis. Despite the serological-marker negativity, the results of immun ostaining for HBsAg and HBcAg support replication and expression of HB V DNA, though weak.