HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (Papers in Press[PDF]) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Google Scholar Articles by Abu-Ali, G. S Articles by Manning, S. D PubMed PubMed Citation Articles by Abu-Ali, G. S Articles by Manning, S. D Agricola Articles by Abu-Ali, G. S Articles by Manning, S. D

Differences in adherence and virulence gene expression between two outbreak strains of enterohemorrhagic Escherichia coli O157:H7

michigan state university

The Escherichia coli O157:H7 TW14359 strain was implicated in a multi-state outbreak in North America in 2006, which resulted in high rates of severe disease. Similarly, the O157:H7 RIMD0509952 (Sakai) strain caused the largest O157:H7 outbreak to date. Both strains were shown to represent divergent phylogenetic lineages. Here we compared global gene expression patterns before and after epithelial cell exposure as well as the ability to adhere to and invade epithelial cells between the two outbreak strains. Epithelial cell assays demonstrated a 2.5 fold increase in adherence of the TW14359 strain relative to Sakai, while whole-genome microarrays detected significant differential expression of 914 genes, 206 of which had a fold change 1.5. Interestingly, most locus of enterocyte effacement (LEE) genes were upregulated in TW14359, whereas flagellar and chemotaxis genes were primarily upregulated in Sakai, suggesting discordant expression of these genes between the two strains. The Shiga toxin 2 genes were also upregulated in the TW14359 strain as were several pO157-encoded genes that promote adherence, including type II secretion genes and their effectors stcE and adfO. Quantitative RT-PCR confirmed the expression differences detected in the microarray analysis, and expression levels were lower for a subset of LEE genes before versus after exposure to epithelial cells. In all, this study demonstrated the upregulation of major and ancillary virulence genes in TW14359 and of flagellar and chemotaxis genes in Sakai, under conditions that precede intimate bacterial attachment to epithelial cells. Differences in the level of adherence to epithelial cells were also observed, implying that the two phylogenetically divergent O157:H7 outbreak strains vary in their ability to colonize, or initiate the disease process.

¹ E-mail: shannon.manning{at}ht.msu.edu