Figure 3
Numbers of bacterial masses does not scale with MOI. (a) Percentage (%) of RAW264.7 macrophages with internalised bacteria. Media (grey bars), S. aureus MOI 5 (shaded bars) or MOI 50 (black bars) was added to macrophages, centrifuged onto cells and incubated until 2.5 h post-infection, bars represent mean percentage ± SEM, with dotted lines showing 1% and 20% (n = 4). (b) representative image of RAW264.7 macrophages (red) with internalised bacteria after GFP S. aureus (green) were centrifuged onto cells and incubated for 2.5 h at MOI 5, (scale bar 50 µm). (c–f), RAW264.7 macrophages were infected with GFP and mCherry S. aureus in a 1:1 ratio with a total MOI as designated. The number of single- or dual-colour bacterial masses detected at 25 h post-infection is indicated, showing mean values ± standard deviation; (c) S. aureus (MOI = 5) was centrifuged onto cells before incubation (n = 4); (d) MOI = 10 (n = 4); (e) MOI = 20 (n = 3); (f) MOI = 50 (n = 5), GFP (cyan), mCherry (magenta), media control (grey), dual (black) Cells in d-f were uncentrifuged. (g–h), Comparison between number of total single-colour (grey) and dual-colour masses (black) for ratio data presented in (d–f); (g) summary of average plots for (d–f); (h) total single-colour and dual-colour masses were combined from (d–f), data are presented as mean ± standard deviation, **p < 0.005, ****p < 0.0001, as determined by Kruskal–Wallis test with Dunn’s post-hoc test for panels (d–g) or two-tailed Mann–Whitney test for panel (i).
