Submitted to: American Society for Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 2/12/2008
Publication Date: 5/22/2008
Citation: Dowd, S.E., Sun, Y., Rhoads, D., Domingo, A.R., Smith, E., Wolcott, R. 2008. Genome sequence of two separate Escherichia coli O157:H7 isolates from lineage 2 confirm disruption in bacteriophage encoding Shiga toxin 2 [abstract]. 108th American Society for Microbiology Annual Meeting, June 1-5, 2008, Boston, MA. Abstract No. P-075. Interpretive Summary:
Technical Abstract: The existence of two separate lineages of E. coli O157:H7 has previously been reported, and research indicates that one of these lineages (lineage I) might be more pathogenic towards human hosts.We have previously shown that the more pathogenic lineage expresses higher levels of Shiga toxin 2 (Stx2) than the non-pathogenic lineage II. To evaluate why lineage 2 isolates do not express appreciable levels of toxin, whole genome sequencing was performed using Roche Applied Science/454 GS-FLX technology. Two lineage 2 isolates (FRIK966 and FRIK2000) were chosen as representatives of lineage 2 and performed massively parallel picolitre-scale pyrosequencing reactions followed by denovo assembly and evaluation of the primary contigs encoding the stx2AB. These assemblies were then compared to two lineage 1 genome sequences. This analysis reveals that IS629 rearrangements may be associated with disruption of the bacteriophage encoding stx2AB in the lineage 2 isolates. This supports our hypothesis that lineage 2 isolates may be less of a risk as foodborne pathogens. Work is now underway to finish these genomes and evaluate other virulence factors, particularly those associated with intimate attachment.