TABLE 1.
Escherichia coli strains and plasmids used in the studya
| Strain | Relevant properties | Plasmid | Reference |
|---|---|---|---|
| G58-2 | Nonpathogenic porcine E. coli field isolate | 11 | |
| 04-21018 | Porcine ETEC isolate | F18/STa/STb/Stx2e | 50 |
| 8221 | LT192 construct, 1836-2/pLT192 | pLT192/pBR322 | Zhang and Francis, submitted |
| 8227 | Host strain, G58-2/987P | pDMS167 | This study |
| 8795 | Host strain, G58-2/987P | pDMS158 | This study |
| 8331 | Control, G58-2/987P/pACYC184 | pACYC184 | This study |
| 8330 | pSTa recombinant, G58-2/987P/STa | pSTa/pACYC184 | This study |
| 8413 | pSTa11 mutant, G58-2/987P/STa11 | pSTa11/pACYC184 | This study |
| 8415 | pSTa12 mutant, G58-2/987P/STa12 | pSTa12/pACYC184 | This study |
| 8417 | pSTa13 mutant, G58-2/987P/STa13 | pSTa13/pACYC184 | This study |
| 8474 | pLT192:pSTa12, G58-2/987P/LT192:pSTa12 | pLT192:pSTa12/pACYC184 | This study |
| 8475 | pLT192:pSTa13, G58-2/987P/LT192:pSTa13 | pLT192:pSTa13/pACYC184 | This study |
| 8552 | pLT192:pSTa12, TOPO 10/LT192:STa12 | pLT192:pSTa12/TA vector | This study |
| 8554 | pLT192:pSTa13, TOPO 10/LT192:STa13 | pLT192:pSTa13/TA vector | This study |
| 8823 | pSTa challenge strain, G58-2/987P/pSTa | pSTa/pUC19 | This study |
a
The porcine E. coli field isolate G58-2 was used as a parental strain and was transformed with plasmid pDMS167 (34) or pDMA158 (8) to express 987P fimbriae (G58/987P). G58/987P was further transformed with plasmids expressing a native pSTa, a mutated pSTa, or a pLT192:STa-toxoid chimeric plasmid to give a porcine STa recombinant strain, three STa mutant strains, and pLT192:pSTa12 and pLT192:pSTa13 fusion constructs. In addition, TOPO 10 cells and TA cloning vectors (Invitrogen) were used for expression and purification of the pLT192:pSTa12 and pLT192:pSTa13 fusion proteins.