Although HCMV can infect many different cell and tissue types, the virus has a set number of viral entry complexes that can be used, which means the virus has adapted to utilize these complexes in a way that promotes efficient transmission and infection of different cell types in the new host to allow for lifelong persistence (see Figure 1 for a cartoon of viral glycoproteins and their cognate ligands on monocytes/CD34+ HPCs and other cell types). The gene discussed is CD34; the disease is infection.