Detection of endogenous human cytomegalovirus in CD34+ bone marrow progenitors.

The cellular sites and mechanisms of human cytomegalovirus (HCMV) latency are still poorly defined. Although evidence suggests that peripheral blood monocytes are one site of latency in the healthy carrier, it is unlikely that monocytes represent a site of primary HCMV infection. Consequently, we have analysed CD34+ bone marrow progenitors, precursors of monocytes, to determine whether they are a site of HCMV carriage in normal virus carriers. For the first time, we demonstrate the presence of endogenous HCMV within bone marrow progenitors in the absence of HCMV lytic gene expression. These findings are consistent with previous evidence showing that the permissiveness of myeloid cells for HCMV is critically dependent on the differentiation state of the cell.