Histopathologic impact of TT virus infection on the liver of type C chronic hepatitis and liver cirrhosis in Japan

The present investigation compared the histological findings in the liver o f chronic hepatitis C patients who were or were not co-infected with TT vir us (TTV) to determine the histological and clinical characteristics of TTV infection. One hundred eighty patients with chronic hepatitis or liver cirr hosis type C were included in this study. Serum samples were tested for the presence of TTV DNA by a nested polymerase chain reaction. The liver biops y specimen of each patient was examined, and scores were assigned to indica te the severity of each of the following features: inflammatory cell infilt ration in the periportal, parenchymal, and portal areas; fibrous stage; lym phoid reaction in the portal area; portal sclerotic change; perivenular fib rosis; pericellular fibrosis; damage of bile duct; and irregular regenerati on of hepatocytes. Sixty-four (34.4%) of the 180 patients were positive for TTV DNA. The histological features of the liver and the blood biochemical parameters of the TTV DNA-positive and TTV DNA-negative patients, did not d iffer significantly except for the score of irregular regeneration (IR) of hepatocytes. Among those in the F4 stage of fibrosis, the score of IR of th e TTV DNA-positive patients was significantly higher than that of the TTV D NA-negative patients. In conclusion, chronic TTV infection does not modify the biochemical features of chronic hepatitis type C patients. TTV may be a risk factor, however, for the development of hepatocellular carcinoma in p atients with type C liver disease in the F4 stage. J. Med. Virol. 64:74-81, 2001. (C) 2001 Wiley-Liss, Inc.