CD34 and disease arising from reactivation of latent virus: 21, 22, 23 As a herpesvirus,42 CMV is known to establish latent infection in bone marrow progenitor cells and create devastating consequences by spreading to other tissues from the bone marrow.17, 18 One potential anti-CMV approach is to transfer EGS expression cassettes to the progenitor cells associated with the bone marrow, such as CD34+ cells, and express EGSs to control viral infection in these cells and in vivo.