Human herpesvirus-6 and acute liver failure1

Abstract
Background. In patients with acute liver failure (ALF) of unknown cause, viral infections are believed to be involved. This study investigates the involvement of human herpesvirus-6 (HHV-6). Methods. Thirty-two patients with ALF who underwent transplantations during a 6-year period were studied for viruses in biopsies from their explanted livers. Non-A to non-E hepatitis (unknown) ALF was the reason for transplantation in 15 patients, and another 17 patients with a known disease from the same time period served as controls. The explanted livers were examined for hepatitis viruses and other possible viral agents. HHV-6 antigens were demonstrated in the livers and blood mononuclear cells by immunoperoxidase staining. Results. Of the 15 patients with ALF of unknown cause, 12 (80%) demonstrated HHV-6 antigens in the liver. Most of these patients (10/12) also demonstrated HHV-6 antigenemia. The predominant histologic finding of HHV-6 infection was moderate to severe portal lymphocytic infiltration. HHV-6 was found in 4 of 17 control patients, and cytomegalovirus was found in 2 of 17 control patients (in the blood and explanted liver). No other viruses were found in the livers of the patients with ALF. Conclusions. HHV-6 was found in most explanted livers of patients with ALF of unknown cause. HHV-6 antigenemia was associated with HHV-6 antigens in the liver. Only a few control patients displayed HHV-6 in the liver. These observations indicate that HHV-6 may be one of the causes of ALF.