Skip to main content
ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Food Safety and Enteric Pathogens Research » Research » Publications at this Location » Publication #410249

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: Tissue localization and acute peripheral transcriptomic response following Salmonella enterica Typhimurium infection of pigs

Author
item Loving, Crystal
item WIARDA, JAYNE - Oak Ridge Institute For Science And Education (ORISE)
item Byrne, Kristen
item Anderson, Christopher

Submitted to: Conference Research Workers Disease Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 1/1/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Objectives Most foodborne isolates of Salmonella cause an acute, self-limiting, transient disease in swine, though it can be recovered from lymphoid tissues for weeks following infection. A clear understanding on the immune response to acute and persistent Salmonella infection in pigs is a necessary first step to developing targeted intervention strategies for preharvest reduction. The main objectives were to understand the acute and transitioning peripheral immune response of pigs to Salmonella inoculation and evaluate early Salmonella localization to immune cells in tissues. Methods Groups of pigs (n=5 per timepoint) were oronasally inoculated with Salmonella enterica serovar Typhimurium (ST) or mock-inoculated and blood collected at 2 and 8 days post-inoculation (dpi). Necropsies were performed on day 2 and 8 dpi to collect tonsil, cecum, and cecal contents. Whole blood RNA was extracted and sequenced. PBMC were isolated, cryopreserved, thawed, and subjected to partitioning and labeling (10X Genomics), and sequencing. ST enumeration was performed on cecal contents and tonsils. ST abundance and localization in tonsil and cecum was assessed using immunohistochemistry (IHC), including association with myeloid cells. Results ST was recovered from tonsil at 2 and 8 dpi, but only on 2 dpi from cecal contents. However, IHC revealed little ST in tonsil cells, suggesting extracellular ST detection using culture. ST-positive cells were detected in cecum. In whole blood, more than 400 genes were increased in expression over controls on 2dpi, but by 8dpi no significant differences were noted between mock and ST groups. Genes associated with macrophage activation and myeloid leukocyte activation were increased (GO terms). Single-cell RNA-sequencing analysis revealed specific cell types responding to ST infection, mostly resolved by 8 dpi. Conclusions ST inoculation caused a transient, but robust peripheral immune activation. Deciphering the immune response, particularly at the single-cell level revealed responses of specific cell types. IHC paired with culture methods suggested differences between detection of extracellular and intracellular ST, particularly in tissues relevant for persistence.