Dendritic-cell infection by human cytomegalovirus is restricted to strains carrying functional UL131–128 genes and mediates efficient viral antigen presentation to CD8+ T cells

Abstract

Human cytomegalovirus (HCMV) genetic determinants of endothelial-cell tropism and virus transfer to leukocytes (both polymorphonuclear and monocyte) have been recently identified in the UL131-128 genes. Here it is documented that the same genetic determinants of HCMV are responsible for monocyte-derived dendritic-cell (DC) tropism, i.e. all endotheliotropic and leukotropic strains of HCMV are also DC-tropic (or dendrotropic). In fact, all recent clinical HCMV isolates and deletion mutants sparing the UL131-128 locus as well as the endotheliotropic revertants AD169 and Towne were able to productively infect DC following co-culture with infected endothelial cells. On the contrary, the same clinical isolates extensively propagated in human fibroblasts, the UL131-128 deletion mutants and the reference laboratory strains were not. Peak extracellular virus titres in DC were reached 4-7 days post-infection (p.i.). Viral proteins pp65 and p72 were detected 1-3 h p.i., involving the great majority of DC 24 h p.i., while gB was abundantly detected 96 h p.i., when a cytopathic effect first appeared. Infection of DC with cell-free virus released into the medium could only be achieved with HCMV strains extensively adapted to growth in endothelial cells, reaching the peak titres 10 days p.i. DC infected for 24 h with cell-free virus and incubated for 16 h with autologous peripheral blood mononuclear cells were found to act as a potent stimulator of both HCMV-specific CD4 + -and CD8 + -mediated immune responses, as determined by cytokine flow cytometry. DC incubated with inactivated crude whole viral antigen preparations were only capable of eliciting a significant CD4 + -mediated immune response.

Simultaneous quantification of human cytomegalovirus (HCMV)-specific CD4+ and CD8+T cells by a novel method using monocyte-derived HCMV-infected immature dendritic cells

“…HCMVspecific T cell response is evaluated using as a stimulus autologous monocyte-derived immature DC infected with an endotheliotropic (Huv + ) and leukotropic (Leuk + ) HCMV strain [15].…”

The pentameric complex of human Cytomegalovirus: cell tropism, virus dissemination, immune response and vaccine development

“…A critical breakthrough was represented by the identification of the PC, which consisted, as mentioned above, of the UL128L products complexed with gH and gL to form the PC-mediating entry complex for epithelial and endothelial [9] as well as dendritic [109] cells and M/M [110,111]. As a result, several investigators have suggested including the PC in vaccine designs [112].…”

Identification and Characterization of U83A Viral Chemokine, a Broad and Potent β-Chemokine Agonist for Human CCRs with Unique Selectivity and Inhibition by Spliced Isoform

“…In human CMV (HCMV), for example, the UL146 chemokine is specific for ␣-chemokine receptors and can control dissemination of the virus in specifically chemoattracted neutrophils (16). There is another locus encoding a potential HCMV chemokine, UL131-128, and this also appears to affect endothelial, leukocyte, and dendritic cell (DC) tropism, in that passage in fibroblasts results in deletion or alteration at this locus (17)(18)(19). At least one transcript here encodes similarities to ␤-chemokines, which can chemoattract monocytes, and a similar function in murine CMV, vMCK, has been shown essential for virus dissemination (20 -22).…”