Extended Data Fig. 4.

(a) Histology of tumor sections taken from mice with different treatments 3 days post administration: (i) H and E staining for tissue sections intravenously injected with a combination of therapeutic bacteria (SLC-3), chemotherapy (5-FU), or a bacteria control with no therapeutic (Strain 7). (ii) TUNEL staining (red) in the same sections indicating cell apoptosis. (iii) Salmonella immunohistochemistry (red) in the same sections confirming presence of bacteria in tumors. Scale bars for (i), (ii), and (iii) denote 50μm. (iv) and (v) TUNEL and Salmonella staining (red) in the entire tumor sections (examples indicated by arrows). Scale bars for (iv) and (v) denote 100μm. DAPI staining (blue) was used to obtain a measure of live and dead cells in (ii) - (iv). Histology slices (n=6) from 20x images were compared across the groups and mean intensity of TUNEL staining, normalized by sample area, was demonstrated to be significantly higher for SLC-3 compared to the other two groups (P<0.0001, one-way ANOVA), and not significantly different between the chemotherapy and bacteria only cases.