Figure 4From: Systems analysis of multiple regulator perturbations allows discovery of virulence factors in SalmonellaVirulence study on putative effector proteins. To compare the viability of deletion strains lacking putative effector proteins with that of wild-type Salmonella, competitive infection was performed in five 129SvJ mice for each mutant. ΔsrfN, ΔpagK2, and ΔpagJ/pagK1/pagK2 were transformed with pSrfN or pPagK2 to test virulence complementation, whereas wild-type Salmonella was transformed with an empty plasmid, pWKS30. A reference strain (MA6054) harboring arabinose-inducible β-galactosidase activity and each test (wild-type or mutant) strain were mixed equivalently and 10,000 CFU of the mixed cells was used to infect a mouse. Mice were sacrificed at 7 days post-infection and the spleen lysates were spread on plates containing X-gal and arabinose to compare the numbers between the wild-type strain and the mutant strain. The competitive index (CI) was determined by the formula described in Methods. Each circle represents the CI for a single mouse in each group. A CI of less than 1 indicates that a test strain is outcompeted by the reference strain in mouse. The averaged CI for each group is shown as a solid line and statistically significant p-value is indicated with an asterisk (p-value < 0.001, Student's t-test).Back to article page