SseF and SseG function in trans in modifying the host cell endosomal system.
HeLa cells were infected with individual Salmonella WT, sseF or sseG strains each harboring a plasmid for expression of mCherry. Further cells were co-infected with a mixture consisting of sseF and sseG strains expressing mCherry or GFP for distinction of the strains. As controls, co-infection with sseF strains expression mCherry or GFP or sseG strains expressing mCherry or GFP was performed. In order to obtain sufficient numbers of co-infected cells, an MOI of 100 was used. A) SIF formation in representative cells co-infected with sseF [mCherry] (red) and sseG [GFP] (green). The cells were fixed 16 h p. i. and immuno-stained for LAMP2 (shown in white). Arrows indicate continuous SIF in co-infected cells. Scale bar: 20 µm. B) HeLa cells infected with single strains or co-infected with strains were identified and scored for formation of SIF or pseudo-SIF. At least 50 cells per condition were scored and the mean percentages and standard deviations of three independent experiments were calculated for infected/co-infected cells showing SIF (filled bars) or pseudo-SIF (open bars).