CD8A and cytomegalovirus infection: The magnitude of HCMV-specific CD8+ T-cell recovery predicts the risk of progressive HCMV infection [8, 9], but HCMV replication after HSCT also depends on the presence of dysfunctional HCMV-specific CD8+ T cells rather than on the absolute numbers of HCMV-specific T cells [10, 11].