Human herpesvirus-6 antigenemia after liver transplantation

Background. Human herpesvirus (HHV)-6 has recently been reported in liver t ransplant patients. It infects and causes dysfunction in hepatic transplant s, which provides serious differential diagnostic problems between allograf t rejection and viral infection. The diagnosis of posttransplantation HHV-6 infection is usually based on serology or on polymerase chain reaction det ection of viral DNA in peripheral blood specimens. However, serology does n ot tell the exact time of the infection, and detection of viral DNA by poly merase chain reaction may also indicate a latent infection in seropositive patients. Here we report the diagnostic use of frequent monitoring of HHV-6 antigenemia after liver transplantation. Methods. Altogether 622 blood specimens from 51 consecutive adult liver tra nsplant patients were analyzed. The diagnosis was based on demonstration of HHV-6-specific antigens in peripheral blood mononuclear cells using immuno peroxidase staining and monoclonal antibodies and on serology. Results. During the first year (7-280 days) after transplantation, HHV-6 in fection was diagnosed in 11 (22%) of 51 patients. HHV-6 early antigens, as well as HHV-6 variant B antigens, were detected in all 11 patients. HHV-6 d iagnosis was confirmed by serology. The episode of HHV-6 antigenemia usuall y lasted for several weeks together with mild, if any, clinical signs of th e infection. A significant graft dysfunction was associated with HHV-6 anti genemia in 8 of 11 patients, and viral antigens were also detected in the l iver biopsy specimens of 3 of these patients. Conclusions. An active HHV-6 infection can be diagnosed from peripheral blo od by detection of virus-specific antigens in mononuclear cells. HHV-6 anti genemia correlated with seroresponse.