Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/3/2011
Publication Date: 10/7/2011
Citation: Sharma, V.K., Bearson, S.M., Thacker, T.C. 2011. Enterohemorrhagic Escherichia coli O157:H7 requires quorum sensing transcriptional regulators QseA and SdiA for colonization and persistence in the bovine intestinal tract [abstract]. 71st Annual Meeting of the North Central Branch of the American Society for Microbiology. October 7-8, 2011, Des Moines, Iowa. 59:147.
Technical Abstract: QseA and SdiA are two of several transcriptional regulators that regulate virulence gene expression of enterohemorrhagic Escherichia coli (EHEC) O157:H7 via quorum sensing (QS). QseA regulates the expression of the locus of enterocyte effacement (LEE). LEE encodes for a type III secretion (T3S) system for secreting proteins that promote adherence of EHEC O157:H7 to epithelial cells, tissue colonization and persistence of these bacteria in bovine intestines. SdiA directly or indirectly regulates LEE, and the genes essential for motility and biosynthesis of flagella and curli fimbriae. In this report, we describe the requirement of QseA and SdiA in persistence and fecal shedding of EHEC O157:H7 in cattle. Weaned calves (n = 6 per group) were orally dosed with 10**10 cfu of wild-type EHEC O157:H7, qseA mutant, or sdiA mutant strains, and fecal shedding of these strains was monitored over 28 days. The magnitude and duration of fecal shedding were reduced for qseA and sdiA mutants compared to the wild-type strain. Although in vitro HEp-2 cell adherence was similar between the qseA mutant and the wild-type strain, the transcriptional levels for LEE, flagellar, and fimbrial genes were reduced in the qseA mutant. The sdiA mutant showed increased adherence to HEp-2 cells and increased expression of flagellar and curli genes, but no significant differences in LEE gene expression. These results indicate that EHEC O157:H7 requires QseA and SdiA to presumably sense the presence of varied QS signals to modulate its gene expression profile for survival and colonization in the bovine gastrointestinal tract.