Macrophage cultures are susceptible to lytic productive infection by endothelial-cell-propagated human cytomegalovirus strains and present viral IE1 protein to CD4+ T cells despite late downregulation of MHC class II molecules

Abstract

The contribution of CD4+ T cells to control of human cytomegalovirus (HCMV) has been shown and infected tissue macrophages might contribute to this response by antigen presentation. As shown previously, CD4 + T cells recognize HCMV immediate-early antigen IE1 on glioblastoma cells manipulated to express MHC class II molecules. Here, the possible interference of virus-induced MHC class II downmodulation with the presentation of IE1 by natural target cells was analysed. The capacity of IE1-specific CD4 + T-cell clones to recognize HCMV-infected monocyte-derived macrophages was tested. Various HCMV strains were used to achieve efficient infection of macrophages. Activation of CD4 + T cells by infected macrophages was evaluated at different time points after infection. Endothelial-cell-adapted HCMV strains efficiently infected cultured human macrophages. However, the immediate-early and early phases of replication were prolonged. Infected cells entered the late replication phase only after 3 days of infection, which was associated with downmodulation of MHC class II molecules at the surface of infected cells. Strong stimulation of IE1-specific CD4 + T cells resulted from endogenous de novo antigen production and presentation by infected macrophages during the first 3 days of virus replication, despite MHC class II downmodulation in the late replication phase. Therefore, infected macrophages are assumed to contribute to the antiviral immune response in infected organs.

Human Cytomegalovirus (HCMV) Infection of Endothelial Cells Promotes Naïve Monocyte Extravasation and Transfer of Productive Virus To Enhance Hematogenous Dissemination of HCMV

“…Endothelial cells were infected at a multiplicity of infection (MOI) of 5 or 20 or mock infected with medium alone. This endothelial cell-tropic strain of HCMV also efficiently infects monocytes (81), as does our Towne/E strain (84,85,103). We found that 100% of the endothelial cells and 100% of monocytes were infected with TB40-UL32-HCMV/E and Towne/E when we used an MOI of 5 or an MOI of 20.…”

A Myeloid Progenitor Cell Line Capable of Supporting Human Cytomegalovirus Latency and Reactivation, Resulting in Infectious Progeny

“…These model systems support HCMV latent infection, and importantly, the latent virus can be reactivated, producing infectious progeny (12,14,16,50,55,56). However, these primary cell systems are hampered by finite cell numbers coupled with lower infectivity rates, limited life span ex vivo, donor variation, the complexity of a heterogeneous population, and the inability to exploit current molecular biology tools to manipulate gene expression.…”

“…Ex vivo latency models that utilize primary CD34 ϩ /CD38 Ϫ hematopoietic progenitor cells (HPCs) isolated from bone marrow or umbilical cord blood (13,14,26,35,42), as well as peripheral blood monocytes (7,16,27,33,50,52,56,58,67), represent perhaps a more complete assessment of HCMV latency. These model systems support HCMV latent infection, and importantly, the latent virus can be reactivated, producing infectious progeny (12,14,16,50,55,56).…”

Mutational Mapping of UL130 of Human Cytomegalovirus Defines Peptide Motifs within the C-Terminal Third as Essential for Endothelial Cell Infection

“…While HCMV infection is usually clinically unapparent in the immunocompetent host, it can cause severe disseminated infections under conditions of immunosuppression, with manifestations in the lung, retina, and gastrointestinal tract, among others (12). Various cell types support viral replication, including epithelial cells and endothelial cells (ECs), smooth muscle cells, fibroblasts, and cells of hematopoietic origin (13,14,18,19,25,26,37). Among these target cells, endothelial cells are assumed to contribute particularly to hematogenous dissemination of HCMV (24).…”