Overview: cytomegalovirus and the herpesviruses in transplantation

Herpesviruses infect most animal species. Infections due to the eight human herpesviruses (HHV) are exacerbated by immunosuppression in organ transplantation. The special features of the herpesvirus life cycle include the ability to establish latent, nonproductive infection and the life-long capacity for reactivation to productive, lytic infection. Interactions between latent virus and the immune system determine the frequency and severity of symptomatic infections. The immunologic and cellular effects of herpesvirus infections contribute to risk for opportunistic infections and graft rejection. Among the most important advances in transplantation are laboratory assays for the diagnosis and monitoring of herpesvirus infections and antiviral agents with improved efficacy in prophylaxis and therapy. For herpes simplex virus, varicella zoster virus and cytomegalovirus, these advances have significantly reduced the morbidity of infection. The syndromes of EBV-associated posttransplant lymphoproliferative disorders (PTLD) and Kaposi's sarcoma remain important complications of immunosuppression. The epidemiology and essential biology of human herpesvirus is reviewed.