Table 1.
Phenotypes of S. typhimurium sopE mutant
| Strain | Relevant genotype | Henle-407 invasion,* % | J774 toxicity,† % | Mouse virulence (mean time to death),‡ days | Rescue of invasion phenotype,§ % |
|---|---|---|---|---|---|
| SL1344 | Wild type | 42 ± 8 | 23 ± 5 | 6 | 100 ± 10 |
| SB136 | invA::aphT | 0.2 ± 0.05 | 3 ± 1 | ND | <1 |
| SB757 | sopE | 40 ± 5 | 21 ± 5 | 6 | 40 ± 5 |
| SB757 (pSB1130) | sopE (sopE+) | 53 ± 10 | ND | ND | 100 ± 10 |
| SB756 | orfJ:aphT | 43 ± 5 | 24 ± 5 | 6 | ND |
Entry into Henle-407 cells was determined by the gentamicin-resistance assay. Values are the mean ± the standard deviation of six independent determinations and represent the percentage of the bacterial inoculum that survived 2 h of gentamicin treatment. Equivalent results were obtained with strain SB856.
Macrophage J774 cytotoxicity was determined by a dye exclusion assay (22). Values are the percentage of cells exhibiting cytotoxicity after 30 min of infection. At least 200 cells were evaluated in each assay. Equivalent results were obtained with strain SB856. ND, not done.
BALB/c mice (six per group) were infected orally with 106 bacteria. Virulence is given as mean time to death. There were no survivors in any group.
The ability of the different strains to rescue the entry phenotype of the invasion-defective S. typhimurium sipB strain SB169 was measured as described in the text. Values were standardized considering the rescue ability of wild type to be 100%. Equivalent results were obtained with strain SB856.