CeBiTec Colloquium: Dr. Eckhard Strauch, Bundesinstitut für Risikobewertung (BfR), Berlin Fachgruppe Molekulare Diagnostik und Genetik

2008/02/07, 12:30

University Building, Room V6-138

Dissimination of the Shiga toxin variant 2c in EHEC O157 by a lysogenic phage

Abstract:

Shiga toxin (Stx) (verocytotoxin)-producing strains of Escherichia coli O157 are important human pathogens that can cause severe disease, such as hemorrhagic colitis and hemolytic uremic syndrome (HUS).The production of Shiga toxins is a major virulence factor and the genes encoding Stx are located on prophages that are integrated into the chromosome of the bacteria. We isolated a bacteriophage from the human strain CB2851 that encodes the Shiga toxin 2c variant and is able to convert laboratory E.coli K12 strains to toxin production after infection. Genome sequencing revealed that the phage genome has a mosaic structure typical for lambdoid phages. The integration site of the phage into the chromosome was determined and functional studies with repressor and antirepressor genes were carried out. A number of PCR analyses were performed which indicate that a phage homologous to 2851 contributed significantly to the dissemination of the Stx2c variant toxin within this group of E. coli.