Fig. 5

Analysis of TB40E progeny from THP-1 macrophages (lytic model), and MRC5 fibroblasts. a and d MRC5 fibroblasts were infected with cell culture medium derived from THP-1 lytic model (a) or from MRC5 fibroblasts (d) which had been infected with HCMV TB40E at MOI of 0.5 (panels a, a’), 0.25 (panels b, b’) and 0.125 (panels c, c’) for 7 days. At 24 h p.i., MRC5 cells were fixed and labelled with a monoclonal antibody specific for the common epitope encoded by exon 2 of HCMV IE1 and IE2 genes. The immunoreaction was revealed by Alexa-Fluor FITC-conjugated goat anti-mouse IgG (panels a, b, c, d: FITC, green nuclei). Cells were counterstained with Evans blue (panels a, b, c, d: red cells) and DAPI (panels a’, b’, c’, d’: blue nuclei). Panels d, d’: uninfected cells. Images were collected using a conventional fluorescence microscopy. Bar: 25 μm. b and e The quantitative evaluation of IE-positive MRC5 fibroblasts infected with the cell culture medium derived from THP-1 lytic model (b) or MRC5 fibroblasts as already described (see Fig. 3 legend) (e). c and f Virus yields were evaluated by the TCID₅₀ assay from cell culture medium derived from THP-1 lytic model (c) or MRC5 fibroblasts (f), as detailed in the “Methods” section. Two independent experiments were performed; error bars in graphs represent standard deviations. Values were processed by the GraphPad Prism 7 software