Significance of human herpesviruses to transplant recipients

Despite recent great advances in transplantation techniques, herpesvirus infections remain a major cause of morbidity and mortality in transplant recipients. While improvement in immunosuppressive drug regimens have decreased the risk of graft-versus-host disease and rejection in bone marrow transplant recipients and solid organ transplant recipients, all such drugs carry with them an increased risk of herpesvirus reactivation. The following review consolidates recent findings in this field, covering reports published from January 2002 to August 2003.

Real-time polymerase chain reaction has improved the ability to distinguish between latent and active herpesvirus infection, which had been a major difficulty in the diagnosis of such conditions. It has been suggested that evaluation of virus-specific cytotoxic T lymphocyte activity is important for prediction of viral diseases. Development of new antiviral drugs has provided other therapeutic options. However, neither prophylactic nor preemptive administration of antiviral drugs can completely abolish the risk of herpesvirus infection. Transfusion of virus-specific cytotoxic T lymphocytes has been suggested to be a useful treatment for recipients with continuous viral replication due to severe immunosuppression.

Recent progress has been made in learning more about the role of virus-specific cytotoxic T lymphocytes, and developing better diagnostic procedures and therapeutic protocols that are efficient and have reduced adverse side effects. Reliable monitoring methods for viral load, in combination with evaluation of virus-specific cytotoxic T cells, has made possible the prediction of viral diseases and furthered understanding of the role of these cells in controlling viral infections. Furthermore, adoptive immunotherapy has been improved by analyzing host immune responses.