Table 1. Bacterial strains and plasmids.
| Strain or plasmid | Genotype or description | Reference or source |
|---|---|---|
| Strains | ||
| E. coli DH5α λpir | supE44, hsdR17, recA1, endA1, gyrA96, thi-1, relA1, λpir | Susan Gottesman lab |
| E. coli RHO3 (Dap-) | SM10 λpir, KanS, Δasd::FRT, ΔaphA::FRT | [33] |
| S. enterica serovar Typhi Ty2 | Wild type strain, rpoS | Kopecko lab |
| S. enterica serovar Typhi Ty21a | galE, ilvD, viaB (Vi-,) H2S-, rpoS | [23] |
| Ty21a vexA merodiploid (MD290) | Two copies of vexA and FRT site | This study |
| Ty21a-Gad (MD297) | S. flexneri gad genes integrated into tviD-vexA on the chromosome, Kans, Amps, Cams | This study |
| S. flexneri 2457T CFS100 | Avirulent isolate deleted for the invasion plasmid | Shelly Payne lab |
| Plasmids | ||
| pCP20 | yeast Flp recombinase gene FLP, Cmr, Ampr, ts-repa | [34] |
| pMD-SV | Suicide vector with R6K, RP4 and vexA | This study |
| pMD-SD | Suicide vector with R6K, RP4 and tviD | This study |
| pMD-SD-gad | gadABC cloned into pMD-SD | This study |
| pNW129 | P15A rep, Kanr | [37] |
| pGad | gadABC cloned into pNW129 | This study |
a ts-rep; temperature-sensitive replication.