Cloning and Sequencing of Two New Verotoxin 2 Variant Genes of Escherichia coli Isolated from Cases of Human and Bovine Diarrhea

Abstract
We cloned and sequenced two new Verotoxin 2 (VT2) variant genes: one from an Escherichia coli strain from a case of bovine diarrhea and the other from an E. coli strain from a patient with diarrhea. The nucleotide and amino acid sequences of these two genes were highly homologous with, but distinct from those of the VT2, VT2vha, VT2vhb, SLT‐IIv (VT2vp1) and SLT‐IIva (VT2vp2) genes. Their nucleotide sequences were much more closely homologous to that of VT2vh than to that of VT2vp. Search for these two new genes in other Verocytotoxin‐producing E. coli strains resulted in the isolation of 2 strains carrying one of the new VT2 variant genes, one strain from Tokyo and the other from Canada.