Hematopoietic stem cell deficiency resulting from cytomegalovirus infection of bone marrow stroma

Cytomegalovirus (CMV) recurrence from latency is a major risk factor in bone marrow transplantation (BMT). Owing to the immunodepletive treatment, ablation of the immune control of latent CMV is responsible for recurrence and cytopathogenic spread of the virus in vital tissues. There is increasing evidence for reconstituting bone marrow being itself a target tissue of CMV. By inhibiting post-transplantation hematopoiesis, CMV is causal for maintenance of the immunocompromised state, which leads to a prolonged phase of persistent virus replication. Based on results in a murine model of BMT and concurrent CMV infection, we discuss possible mechanisms of CMV-mediated bone marrow graft failure. It is concluded that an irremediable damage of bone marrow stroma by CMV is responsible for a reduced rate of regeneration of the marrow-repopulating, pluripotent stem cell.