The carbon starvation-inducible lipoprotein (Slp) influences differential adherence of Escherichia coli O157:H7 at the bovine rectoanal junction

Authors: Kudva, Indira; BIERNBAUM, ERIKA - Oak Ridge Institute For Science And Education (ORISE); Cassmann, Eric; Palmer, Mitchell; LEKSHMI, EDISON - University Of Florida; CASTELLANOS-GEL, JESSY - University Of Florida; KARIYAWASAM, SUBHASHINIE - University Of Florida

Submitted to: Conference Research Workers Disease Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Shiga toxin-producing Escherichia coli O157:H7 (O157), a foodborne human pathogen, persists at the rectoanal junction (RAJ) of the bovine intestinal tract in asymptomatic cattle reservoirs. Identifying mechanisms used by O157 for initial adherence before persistence at the RAJ could help develop effective O157 control modalities. We recently established the role of carbon starvation-inducible lipoprotein (Slp) in initial adherence of O157 to Caco-2 cells, with the human polymeric immunoglobulin receptor (pIgR) protein as the Slp-receptor. Here, we evaluated the role of Slp in O157 adherence to the bovine RAJ using the RAJ squamous epithelial (RSE) cell- and RAJ-In vitro Organ Culture (IVOC)- adherence assays. The wild-type O157 strain EDL932 (EDL932-WT), it’s isogenic slp deletion mutant (EDL932 'slp), and the slp complemented mutant (EDL932 'slp-p:slp) were tested with no bacteria controls. Adherence was verified by culturing and immunofluorescence (IF) staining of O157. Tissue integrity was determined using nuclear/cell staining dyes and histopathological examination. All test strains adhered in a diffuse-moderate pattern on RSE cells. However, differential adherence was observed on the RAJ-IVOC with the strains preferentially adhering to the columnar cells. Additionally, EDL932-WT and EDL932 'slp-p:slp strains adhered in slightly greater numbers than the EDL932 'slp strain to the RAJ-IVOC, causing disruptions primarily in the columnar region of otherwise intact RAJ-IVOC tissues. Furthermore, pIgR was predominantly detected by IF microscopy and RNAscope in situ hybridization at the columnar region of the RAJ-IVOC tissue. In silico modeling demonstrated the possibility of a bovine pIgR-bacterial Slp interaction. Hence, our observations support the role for Slp in the initial adherence of O157 to the columnar cells at the bovine RAJ, unlike the squamous cells where the loss of slp did not impact attachment. In addition, a possible mucosal immune-interference resulting from the bovine pIgR-Slp interaction could contribute towards long-term O157 colonization of cattle.