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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Food Safety and Enteric Pathogens Research » Research » Publications at this Location » Publication #422919
Research Project: Intestinal Microbial Ecology and Non-Antibiotic Strategies to Limit Shiga Toxin-Producing Escherichia coli (STEC) and Antimicrobial Resistance Transmission in Food Animals

Location: Food Safety and Enteric Pathogens Research

Title: Shedding light on super shedding: Comparative transcriptomics reveals genes uniquely contributing to the aggregative adherence of supershed enterohemorrhagic Escherichia coli to bovine recto-anal junction cells

Author
item CIELO, RYAN - Providence College
item BIERNBAUM, ERIKA - Oak Ridge Institute For Science And Education (ORISE)
item NERI, LUKE - Providence College
item RYKIEL, JOSHUA - Providence College
item WINTERS, SAMANTHA - Providence College
item Kudva, Indira
item MOREAU, MATHEW - Providence College

Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: 3/19/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Enterohemorrhagic Escherichia coli (EHEC) serovar O157:H7 persists as a global threat as a foodborne pathogen and an etiological agent of bloody diarrhea and hemolytic uremic syndrome in humans. The primary reservoir of EHEC is cattle, which are asymptomatically colonized by EHEC in the bovine recto-anal junction (RAJ). The ‘normal’ shed rate of EHEC in cattle is ~100 CFU/g of feces, whereas super shedding (SS) cattle produce greater than 104 CFU/g of feces, significantly increasing their environmental burden and likelihood of transmission to other sources of contamination and potential for human infection. Previous studies have shown the only known commonality between SS isolates is a unique, strong, aggregative adherence phenotype on bovine recto-anal junction squamous epithelial (RSE) cells. To understand the mechanisms responsible for this phenotype, RNA Sequencing (RNAseq) and comparative transcriptomics were performed on an SS (SS17) and a non-SS (EDL933) isolate attached to RSE cells. DNA fingerprinting using the polymorphic amplified typing sequences assay was used to verify the isolates pre- and post-RSE cell adherence assays . The comparison of RSE cell-adherent SS17 and EDL933 transcriptomes revealed SS17 upregulates several genes involved in iron acquisition/metabolism, transport, and stress responses and downregulates genes involved in translation and host/virulence interactions in comparison to EDL933. This pattern was similarly observed in comparing EDL933 to a mutant of EDL933 that has an SS-RSE phenotype. Subsequent analysis of EDL933 and SS17 grown on RSE cells vs. DMEM control showed a considerable number of genes coordinately regulated by both isolates, such as the eut-, gad-, and phn- operons. However, each profile had both genes that were regulated in a manner unique to the isolate (expressed in both isolates, but at different levels or expression patterns), as well as expression of genes unique to each isolate when compared to media control. Interestingly, a sizable portion of genes that are differentially regulated between RSE and media controls are hypothetical genes, some of which are predicted ß-barrel and lipoproteins. In all, identification of the genes uniquely expressed by each strain, as well as genes regulated specifically for the interface between EHEC and RSE cells could potentially reveal novel genes and pathways involved in the distinct adherence patterns of both isolates on RSE cells, and those that drive the SS-phenotype.