These observations correlate with those made ex vivo of natural HCMV latent infections (Reeves et al., 2005), and provide evidence in support of the use of experimentally latently infected CD34+ cells as an effective model for the study of HCMV latent infection and reactivation (Reeves et al., 2005; Reeves and Sinclair, 2010). This evidence concerns the gene CD34 and disease arising from reactivation of latent virus.