Although direct infection of CD34+ HPCs was first reported in 1992 (16), the first model for long-term culture and maintenance of progenitor cell phenotype during in vitro HCMV latency was developed in 2002 using adult bone marrow CD34+ cells directly infected with laboratory strains of HCMV and cultured on irradiated stromal cells (17). The gene discussed is CD34; the disease is infection.