A novel murine model of differentiation-mediated cytomegalovirus reactivation from latently infected bone marrow haematopoietic cells

Abstract

CD34+ myeloid lineage progenitor cells are an important reservoir of latent human cytomegalovirus (HCMV), and differentiation to macrophages or dendritic cells (DCs) is known to cause reactivation of latent virus. Due to its species-specificity, murine models have been used to study mouse CMV (MCMV) latency and reactivation in vivo. While previous studies have shown that MCMV genomic DNA can be detected in the bone marrow (BM) of latently infected mice, the identity of these cells has not been defined. Therefore, we sought to identify and enrich for cellular sites of MCMV latency in the BM haematopoietic system, and to explore the potential for establishing an in vitro model for reactivation of latent MCMV. We studied the kinetics and cellular characteristics of acute infection and establishment of latency in the BM of mice. We found that while MCMV can infect a broad range of haematopoietic BM cells (BMCs), latent virus is only detectable in haematopoietic stem cells (HSCs), myeloid progenitor cells, monocytes and DC-enriched cell subsets. Using three separate approaches, MCMV reactivation was detected in association with differentiation into DC-enriched BMCs cultured in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin 4 (IL-4) followed by lipopolysaccharide (LPS) treatment. In summary, we have defined the kinetics and cellular profile of MCMV infection followed by the natural establishment of latency in vivo in the mouse BM haematopoietic system, including the haematopoietic phenotypes of cells that are permissive to acute infection, establish and harbour detectable latent virus, and can be stimulated to reactivate following DC enrichment and differentiation, followed by treatment with LPS.

Fibroblastic cells are a site of mouse cytomegalovirusin vivolytic replication and latent persistence oppositely regulated byStat1

“…While it is understood that our work did not address each and every organ and cellular site in the body, we targeted our efforts towards the organs that were frequently considered in the study of virus latency. We identified viral genomes in macrophages and endothelial cells, in line with previous reports (6, 7, 11, 24), but we also identified the stromal cells as a major contributor to the pool of latent genomes. It is notable that viral genomes in fibroblastic cells were transcriptionally muted and expressed only few transcripts, predominantly immediate-early ones, in line with previous reports (22, 27, 28).…”

Rat Cytomegalovirus Virion-Associated Proteins R131 and R129 Are Necessary for Infection of Macrophages and Dendritic Cells

“…Entry was significantly reduced for all R131 and R129 mutants in dendritic cells, macrophages, and bone marrow cells, which is consistent with pentamer mutants in other CMV species ( Table 3 ). Previous studies identified CD34+ progenitor cells in bone marrow as a site of CMV latency [ 109 , 110 ]. Further work is necessary to determine if pentamer mutants show impaired abilities to establish latency.…”

The Role of the Human Cytomegalovirus UL133-UL138 Gene Locus in Latency and Reactivation

“…Stress or differentiation pathways are typically associated with reactivation from latency [ 24 , 29 , 36 , 50 , 109 ]. But how does the virus “sense” and “respond” to changes in the infected cell to navigate the “decisions” to sustain the latent program or to reactivate?…”