Viral load, CMV-specific T-cell immune response and cytomegalovirus disease in solid organ transplant recipients at higher risk for cytomegalovirus infection during preemptive therapy

Summary Despite advances in prevention, cytomegalovirus (CMV) recurrence is an important challenge in high-risk organ recipients. The present study prospectively evaluates the impact of CMV-specific T-cell immune response and secondary prophylaxis on the risk of recurrence in a cohort of CMV high-risk organ recipients and whether it is possible to determine a safe standardized viral load value below which CMV disease is unlikely. Thirty-nine recipients were included. Thirty-six had primary infections, and 88.9% recurred. Rate and duration of recurrent CMV infection was similar in patients with and without secondary prophylaxis: 57.9% vs. 53.6%, P = 0.770 and 16 vs. 15 days, P = 0.786, respectively. The only factor independently associated with no episodes of CMV recurrence was the acquisition of CMV-specific T-cell immune response (OR: 0.151, 95% CI: 0.028–0.815; P = 0.028). Cytomegalovirus diseases (N = 5) occurred in patients with CMV viral load above 1500 IU/ml who did not follow the planned monitorization schedule. Our observations suggest that episodes of recurrent CMV infection are common after preemptive therapy despite secondary prophylaxis and that CMV-specific T-cell immune response is associated with a decreased risk of recurrent infections. Preemptive therapy may be safe in patients at high risk for CMV infection with strict close monitoring of the CMV viral load.