Tidsskrift : BMC Genomics , vol. 23 , p. 12 , 2022
Trykt : 1471-2164
Elektronisk : 1471-2164
Publikasjonstype : Vitenskapelig artikkel
Sak : 1
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Background: Enterohemorrhagic Escherichia coli (EHEC) is an emerging health challenge worldwide and outbreaks
caused by this pathogen poses a serious public health concern. Shiga toxin (Stx) is the major virulence factor of EHEC,
and the stx genes are carried by temperate bacteriophages (Stx phages). The switch between lysogenic and lytic life
cycle of the phage, which is crucial for Stx production and for severity of the disease, is regulated by the CI repressor
which maintain latency by preventing transcription of the replication proteins. Three EHEC phage replication units
(Eru1-3) in addition to the classical lambdoid replication region have been described previously, and Stx phages carrying
the Eru1 replication region were associated with highly virulent EHEC strains.
Results: In this study, we have classified the Eru replication region of 419 Stx phages. In addition to the lambdoid
replication region and three already described Erus, ten novel Erus (Eru4 to Eru13) were detected. The lambdoid type,
Eru1, Eru4 and Eru7 are widely distributed in Western Europe. Notably, EHEC strains involved in severe outbreaks in
England and Norway carry Stx phages with Eru1, Eru2, Eru5 and Eru7 replication regions. Phylogenetic analysis of CI
repressors from Stx phages revealed eight major clades that largely separate according to Eru type.
Conclusion: The classification of replication regions and CI proteins of Stx phages provides an important platform
for further studies aimed to assess how characteristics of the replication region influence the regulation of phage life
cycle and, consequently, the virulence potential of the host EHEC strain.