TABLE 1.

Escherichia coli strains and plasmids used in the studya

StrainRelevant propertiesPlasmidReference
G58-2Nonpathogenic porcine E. coli field isolate11
04-21018Porcine ETEC isolateF18/STa/STb/Stx2e50
8221LT192 construct, 1836-2/pLT192pLT192/pBR322Zhang and Francis, submitted
8227Host strain, G58-2/987PpDMS167This study
8795Host strain, G58-2/987PpDMS158This study
8331Control, G58-2/987P/pACYC184pACYC184This study
8330pSTa recombinant, G58-2/987P/STapSTa/pACYC184This study
8413pSTa11 mutant, G58-2/987P/STa11pSTa11/pACYC184This study
8415pSTa12 mutant, G58-2/987P/STa12pSTa12/pACYC184This study
8417pSTa13 mutant, G58-2/987P/STa13pSTa13/pACYC184This study
8474pLT192:pSTa12, G58-2/987P/LT192:pSTa12pLT192:pSTa12/pACYC184This study
8475pLT192:pSTa13, G58-2/987P/LT192:pSTa13pLT192:pSTa13/pACYC184This study
8552pLT192:pSTa12, TOPO 10/LT192:STa12pLT192:pSTa12/TA vectorThis study
8554pLT192:pSTa13, TOPO 10/LT192:STa13pLT192:pSTa13/TA vectorThis study
8823pSTa challenge strain, G58-2/987P/pSTapSTa/pUC19This 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.