The analysis of hematopoiesis in mice latently infected with murine cytomegalovirus

Cytomegalovirus (CMV) has been reported to cause delayed marrow engraftmenl and even graft failure afler BMT. tt has been also reported that platelet recovery is delayed in CMV-seroposiiive patients following BMT. We have thus examined the hematopoiesis of MCMV infected mice which could be used as a model of latent CMV infection. As we have reported, bone marrow (BM) cellularity and number of hernatopoietic progenitor cells (HPCs) decreased in the acute phase of MCMV infection. However, 4 weeks postinfection (pi) of B ALB/c mice with 0.2LD50 of MCMV, where viral replication is not detected in any organs except salivary glands, BM cellularity recovered to the control level. Furthermore, numbers of CFU-GM, BFU-E, and lineage marker negative, c-kil and Sca-1 positive (Lin"c-kit+Sca-1+) cells have also recovered to the control level. However, autologous BM reconstitution in MCMV latently infected mice after intravenous 5-FU(150mg/kg) injection significantly delayed compared with control (P<.05). We then examined the function of hernatopoietic microenvironment to explain this delayed marrow reconstitution. Firstly, mice 4 weeks pi and control mice were irradiated (8.5Gy) and IxIO5 normal BM cells were transferred. Surface colonies of spleens (CFU-S) on day8 and day 12 after the transfer were significantly reduced in MCMV infected mice. Secondly, long-term bone marrow culture was established and the production of non-adherent cells decreased rapidly after recharging normal bone marrow cells in MCMV infected mice. In addition, MCMV IE gene was detected in adherent, but not in non-adherent cells by PCR and in situ hybridization. These results suggests that MCMV exclusively infects microenvironment in MCMV latently infected mice and impairs its supporting capability.