Fig. 1

The knockout strains of CRISPR-Cas components show invasion and replication defects. (A-B) HT-29 cell lines, and peritoneal macrophages were infected with S. Typhimurium strain 14028s wildtype (WT), CRISPR (ΔcrisprI, ΔcrisprII, and ΔΔcrisprI crisprII) and cas operon   (Δcas op) knockout strains along with their respective complements (ΔcrisprI + pcrisprI and ΔcrisprII + pcrisprII). (A) The percentage of invasion/ phagocytosis in intestinal epithelial cells was calculated using CFU analysis of the infected cell lysate and the pre-inocula used for infection. Fold proliferation was calculated by normalizing the CFU at 16 h to 2 h. One-way ANOVA (Dunnett’s multiple comparison test) was used to determine significant differences between the WT and knockout strains, in at least three independent experiments, with at least 3 replicates in each. Error bars indicate SD. Statistical significance is shown as follows: *, p ≤ 0.05; **, p ≤ 0.01; ***, p ≤ 0.001; ****, p < 0.0001; and ns, not significant