CD34 and infection: CD34+ HP/HSCs are susceptible to infection with a number of viruses including HIV-1, HTLV-1, Hepatitis C virus, JC virus, Parvovirus, Human Cytomegalovirus (HCMV), and the Human Herpesviruses (HHV): HHV-5, HHV-6, HHV-7, HHV-8 [3-5,42-52].