Fig 9. Acidification is required for secretion of effector SseJ.

(A) RAW264.7 macrophages were infected with I-switch-electroporated Salmonella WT harboring psseJ-HA for expression of SseJ-HA. Cells were immunostained for Salmonella LPS (green) and HA epitope (red), followed by Alexa488- or cy5-labeled secondary antibodies, respectively, for various time points as indicated. (B) 25 nM BAF or an equal volume of DMSO (A) was used as a control. Samples were imaged by confocal microscopy and analyzed using ImageJ software. Scale bar, 3 μm. SseJ secretion was observed (red puncta) after SseB release from the surface after 3.5 h.