Comprehensive analysis of a peripheral blood transcriptome signature in piglets infected with Salmonella Typhimurium: insight into immune responses

Salmonella Typhimurium (ST) infection in pigs poses a significant threat to animal health and food safety; the intricate mechanisms underlying host–immune responses and pathogen persistence remain poorly understood. To address this knowledge gap, we comprehensively analyzed the peripheral blood transcriptome in piglets infected with ST. We performed histopathological evaluation, blood parameter analysis, advanced RNA-sequencing techniques, and quantitative reverse transcription PCR (RT-qPCR)-based validation. The increasement in the monocyte counts at 2 days post-infection suggested its potential to serve as a hematological marker for ST infection in piglets. Functional and pathway enrichment analyses of the differentially expressed genes highlighted the pivotal roles of innate and adaptive immune responses, notably in pathways associated with Toll-like receptors, NIK/NF-κB signaling, cytokine signaling, and T cell proliferation. RT-qPCR-based validation using peripheral blood mononuclear cells provided additional insights into the immune system dynamics in response to ST infection, revealing the marked elevation of the interleukin (IL)-15, IL-27, and CXCL10 levels being significantly elevated in ST-infected piglets. Our comprehensive analysis underscores the multifaceted impact of ST infection on piglets and offers valuable insights into the host–pathogen interactions and the role of host immune system during ST infection.