Interaction of Salmonella enterica with bovine epithelial cells demonstrates serovar-specific attachment and invasion patterns

Authors: Salaheen, Serajus; Sonnier, Jakeitha - Jackie; KIM, SEON WOO - University Of Maryland; Haley, Bradd; Van Kessel, Jo Ann

Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/4/2020
Publication Date: 3/5/2020
Citation: Salaheen, S., Sonnier, J.L., Kim, S., Haley, B.J., Van Kessel, J.S. 2020. Interaction of Salmonella enterica with bovine epithelial cells demonstrates serovar-specific attachment and invasion patterns. Foodborne Pathogens and Disease. https://doi.org/10.1089/fpd.2019.2765.
DOI: https://doi.org/10.1089/fpd.2019.2765

Interpretive Summary: Salmonella is a leading cause of foodborne disease. Dairy cows are known reservoirs of Salmonella enterica and human salmonellosis has been attributed to the consumption of contaminated dairy and beef products as well as direct exposure to animals. There are many different serovars (groups) within Salmonella enterica; some are known to colonize cattle without causing disease or decreased milk production while other serovars make cattle sick. We don’t have much information on the differences in how these different serovars interact with the epithelium (inner lining) in the cow gut. This study investigated the interaction (attachment and invasion) between Salmonella strains that were isolated from dairy systems (cow feces, raw milk, or the dairy environment) and cultured (in the lab) bovine epithelial cells. The strains represented 13 serovars (Anatum, Cerro, Dublin, Give, Kentucky, Mbandaka, Meleagridis, Montevideo, Muenster, Newport, Oranienberg, Senftenberg, and Typhimurium). Differences in interactions between bacterial cells and bovine cells were observed between strains within the same serovars as well as between strains from different serovars. Strains from the serovar, Dublin, were the most invasive while Kentucky, Mbandaka, Cerro, and Give strains were the least invasive. This is interesting because Salmonella Dublin causes disease in cattle while the other serotypes are rarely associated with illness in cattle. Significant differences in motility were also observed between serovars, a trait that may impact their interaction with the bovine cells. Findings from this study demonstrate an underappreciated level of diversity within strains of the same Salmonella serovar with respect to how they interact with bovine epithelial cells. These results will serve as a baseline for future studies that may identify the mechanisms of asymptomatic Salmonella carriage and bovine salmonellosis so that strategies can be implemented to reduce human exposure to this foodborne pathogen.

Technical Abstract: Dairy cows are known reservoirs of Salmonella enterica and human salmonellosis has been attributed to the consumption of contaminated dairy and beef products as well as direct exposure to animals. Although many S. enterica serovars are known to colonize cattle, there is a dearth of information on the interaction of these with the bovine epithelium. This study investigated the interactions between 26 S. enterica strains from bovine origins representing 13 serovars (Anatum, Cerro, Dublin, Give, Kentucky, Mbandaka, Meleagridis, Montevideo, Muenster, Newport, Oranienberg, Senftenberg, and Typhimurium) with cultured bovine epithelial cells. There were significant differences in the interactions of Salmonella strains within and across serovars with bovine epithelial cells (Tukey's HSD test, p < 0.05). S. Dublin strains were the most invasive while Kentucky, Mbandaka, Cerro, and Give strains were the least invasive (p < 0.05). Significant differences in motility were also observed between serovars. Findings from this study demonstrate an underappreciated level of phenotypic diversity within strains of the same Salmonella serovar and serve as a baseline for future studies that may identify the molecular mechanisms of asymptomatic Salmonella carriage and bovine salmonellosis.