In vivo competition experiments between ∆T6SS
deletion mutants and wild type Salmonella Dublin strain CT_02021853 in orally infected mice. Five six to eight-weeks-old female BALB/c mice were infected orally with 106 CFU of a 1:1 mixture of the corresponding T6SS mutant strain and wild type Salmonella Dublin CT_02021853. After 4 days of infection, mice were eutanized and the cecum, liver and spleen were aseptically removed and homogenized in sterile PBS. Bacterial load recovered from each organ was determined by plating serial ten-fold dilutions on LB agar plates with the appropriate antibiotics. Bars represent mean values ± standard error. Statistical significance was calculated using the Student’s t test. Asterisks indicate the statistical significance of differences between the normalized output ratio and the equivalent ratio in the inoculum. * P value < 0.05.