Cloning and Sequence Analysis of Another Shiga‐Like Toxin IIe Variant Gene (slt‐IIera) from an Escherichia coli R107 Strain Isolated from Rabbit

Abstract
An Escherichia coli R107 strain (O26 serotype) producing a Shiga‐like toxin IIe variant (SLT‐IIera) was isolated from the mesenteric lymph node of a freshly dead rabbit carcass. The entire structural gene for this SLT‐IIera was cloned from chromosomal DNA by PCR using primers based on previously published slt‐IIe sequences. Nucleotide sequence analysis indicated that the slt‐llera gene was very similar to slt‐IIe (formerly called slt‐IIy) from E. coli strains S1191 and 412; five and one nucleotide changes were detected in A and B subunits, respectively, which resulted in changes in amino acid sequences of the corresponding subunits by three and one residues. Recombinant SLT‐IIera and SLT‐IIe produced using an E. coli host‐vector system showed similar cytotoxicity, suggesting that the variations in the structural gene of SLT‐IIera have no significant effect on cytotoxic level.