A wide range of cell types support productive infection (Ibanez et al., 1991; Sinzger et al., 2008), but latency appears to be restricted to primitive bone-marrow-resident CD34+ cells and CD33+ myeloid progenitor cells (Mendelson et al., 1996; Hahn et al., 1998; Reeves et al., 2005b), which retain the latent viral genome as they differentiate into peripheral blood CD14+ monocytes and myeloid dendritic cells (mDCs) (Taylor-Wiedeman et al., 1991, 1994; Hahn et al., 1998; Khaiboullina et al., 2004; Reeves et al., 2005b). Here, CD34 is linked to infection.