Latent human cytomegalovirus: a functional study

Epigenetic control of cytomegalovirus latency and reactivation

Cytomegalovirus (CMV) gene expression is repressed in latency due to heterochromatinization of viral genomes. In murine CMV (MCMV) latently infected mice, viral genomes are bound to histones with heterochromatic modifications, to enzymes that mediate these modifications, and to adaptor proteins that may recruit co-repressor complexes. Kinetic analyses of repressor binding show that these repressors are recruited at the earliest time of infection, suggesting that latency may be the default state. Kidney transplantation leads to epigenetic reprogramming of latent viral chromatin and reactivation of immediate early gene expression. Inflammatory signaling pathways, which activate transcription factors that regulate the major immediate early promoter (MIEP), likely mediate the switch in viral chromatin.

Bilateral cytomegalovirus (CMV) oophoritis mimicking widely metastatic carcinoma: a case report and review of the literature

Ovarian cytomegalovirus (CMV) infection is a rare finding reported in autopsy studies of immunocompromised patients. We report the first case of bilateral CMV oophoritis diagnosed in surgical resection specimens from a 63-year-old woman with metastatic brain lesions undergoing whole brain radiation and steroid treatment. The ovarian involvement of CMV infection was an incidental finding during the colectomy and bilateral salpingo-oophorectomy procedure for gastrointestinal bleeding and presumed ovarian metastases. In contrast to the prevailing dogma, a review of the literature found similar prevalence of pre-menopausal and post-menopausal cases. While age related vasculopathy was thought to be the prevailing mechanism for CMV oophoritis, the observation of an inflammation mediated microthrombosis in our case provides a plausible age independent mechanism suggesting that both restrictive and obstructive vascular changes can be involved in the pathogenesis of CMV oophoritis. To avoid misdiagnosis, both pathologists and clinicians should recognize ovarian involvement by CMV as a possibility in the immunocompromised patient.

Cellular localization of latent murine cytomegalovirus

Herpesviruses typically establish latent infection in their hosts. The cell(s) responsible for harboring latent virus, in most cases, is not known. Using immunofluorescence and PCR-in situ hybridization (PISH), a technique which combines the sensitivity of PCR with the localization and specificity of in situ hybridization, we provide the first direct evidence that endothelial cells are a major site of murine cytomegalovirus (MCMV) DNA in latently infected animals. These findings are consistent with existing knowledge of the biological behavior of CMV, in particular the transmission of latent CMV by solid organ and bone marrow transplantation, in both human and animal models. In addition, we have localized MCMV DNA in the lung alveolar macrophage and in bone marrow cells. Our findings confirm that bone marrow-derived hematopoietic cells are a site of CMV latency and further suggest that bone marrow may be a reservoir of infected progeny capable of migrating into the circulation and establishing latency in various tissues. These findings provide clearly needed insight into the site of latent infection which is central to an understanding of the mechanisms of reactivation.