The study will prospectively determine the clinical utility of CMV cell-mediated immunity using the Quantiferon test. The investigators will use the assay results to tailor the duration of CMV prophylaxis in solid organ transplant patients.

Cytomegalovirus (CMV) disease is an important cause of morbidity in solid organ transplantation recipients and remains the most common opportunistic viral infection in these patients. Standard CMV prevention strategies include universal prophylaxis and pre-emptive therapy with viral load monitoring. However, neither of these strategies has been successful in eliminating CMV disease as seen by high rates of viremia, incidence, and CMV recurrence despite treatment. Recently, the Quantiferon-CMV assay has been shown to predict late CMV reactivation after prophylaxis and to be predictive of viral progression and the need for antiviral therapy in organ transplant recipients who develop low level CMV viremia. The purpose of the current study is to test the clinical strategy of using the Quantiferon-CMV assay in guiding the duration of primary CMV prophylaxis in solid organ transplant patients.

Inclusion Criteria:

• Adult kidney, kidney-pancreas, liver transplant recipient, or heart transplant recipient
• CMV D+/R- patient or any R+ patient who received antithymocyte globulin induction therapy

Exclusion Criteria:

• Unable to comply with protocol
• Campath (Alemtuzumab) induction
• Receiving another investigational compound for CMV treatment or prophylaxis.
• Allergy to valganciclovir or ganciclovir
• Receiving an investigational compound for prevention or treatment of rejection, or participating in another interventional study