Microarray based comparison of two Escherichia coli O157:H7 lineages.
BACKGROUND
Previous research has identified the potential for the existence of two separate lineages of Escherichia coli O157:H7. Clinical isolates tended to cluster primarily within one of these two lineages. To determine if there are virulence related genes differentially expressed between the two lineages we chose to utilize microarray technology to perform an initial screening.


RESULTS
Using a 610 gene microarray, designed against the E. coli O157 EDL 933 transcriptome, targeting primarily virulence systems, we chose 3 representative Lineage I isolates (LI groups mostly clinical isolates) and 3 representative Lineage II isolates (LII groups mostly bovine isolates). Using standard dye swap experimental designs, statistically different expression (P < 0.05) of 73 genes between the two lineages was revealed. Result highlights indicate that under in vitro anaerobic growth conditions, there is up-regulation of stx2b, ureD, curli (csgAFEG), and stress related genes (hslJ, cspG, ibpB, ibpA) in Lineage I, which may contribute to enhanced virulence or transmission potential. Lineage II exhibits significant up-regulation of type III secretion apparatus, LPS, and flagella related transcripts.


CONCLUSIONS
These results give insight into comparative regulation of virulence genes as well as providing directions for future research. Ultimately, evaluating the expression of key virulence factors among different E. coli O157 isolates has inherent value and the interpretation of such expression data will continue to evolve as our understanding of virulence, pathogenesis and transmission improves.
Livestock Issues Research Unit, USDA-ARS, Lubbock, TX, USA. sdowd@lbk.ars.usda.gov
Scot E
SE
Dowd
Hiroshi
H
Ishizaki
D019453:Escherichia coli O157 / Q000145:classification* / Q000235:genetics* / Q000472:pathogenicity; D015964:Gene Expression Regulation, Bacterial; D020411:Oligonucleotide Array Sequence Analysis; D015854:Up-Regulation; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
D037521:Virulence Factors