Cloning of a Vero toxin (VT2) gene from a VT2-converting phage isolated fromEscherichia coli0157: H7

A Vero toxin (VT2 or Shiga-like toxin II)-converting phage was isolated from Escherichia coli 0157: H7 strain J-2. Nontoxigenic E. coli C600 produced VT2 when lysogenized with the toxin-converting phage. EcoRI fragments of the phage DNA were ligated with EcoRI-digested pBR322 or pUC118 and were transformed into E. coli MC1061 or MV1184. Transformants exhibiting VT2 production commonly contained a 4.6 kb EcoRI fragment. It was found that a 2.3 kb KpnI-SphI fragment coded VT2 production and that this fragment hybridized weakly with the 2.1 kb fragment encoding VT1.