DOI: 10.5061/dryad.wwpzgmsm3
title: Inflammatory responses induced by the monophasic variant of Salmonella typhimurium in pigs play a role in the high shedder phenotype and fecal microbiota composition

description: Pigs infected with Salmonella may excrete large amounts
 of Salmonella, increasing the risk of spread of this pathogen in
 the food chain. Identifying Salmonella high shedder pigs
 is therefore required to mitigate this risk. We analyzed immune-associated
 markers and composition of the gut microbiota in specific-pathogen-free
 pigs presenting different shedding levels after an oral infection
 with Salmonella. Immune response was studied through total blood
 cell counts, production of anti-Salmonella antibodies and
 cytokines, and gene expression quantification. Total Salmonella
 shedding for each pig was estimated and hierarchical clustering was used
 to cluster pigs into high, intermediate, and low shedders. Gut microbiota
 compositions were assessed using 16S rRNA microbial community profiling.
 Comparisons were made between control and inoculated pigs, then between
 high and low shedders pigs. Prior to infection, high shedders had similar
 immunological profiles compared to low shedders. As soon as 1 day
 postinoculation (dpi), significant differences in the cytokine production
 level and on the expression level of several host genes related to a
 proinflammatory response were observed between high and low shedders.
 Infection with Salmonella induced an early and profound
 remodeling of the immune response in all pigs, but the intensity of the
 response was stronger in high shedders. In contrast, low shedders
 seroconverted earlier than high shedders. Just after induction of the
 proinflammatory response (at 2 dpi), some taxa of the fecal microbiota
 were specific to the shedding phenotypes. This was related to the
 enrichment of several functional pathways related to anaerobic respiration
 in high shedders. In conclusion, our data show that the immune response
 to Salmonella modifies the fecal microbiota and
 subsequently could be responsible for shedding phenotypes. Influencing the
 gut microbiota and reducing intestinal inflammation could be a strategy
 for preventing Salmonella high shedding in livestock.
description: We analyzed immune-associated markers and composition of the gut
 microbiota (faeces, ileum, caecum) in pigs presenting different shedding
 levels after an oral infection with 10<sup>9</sup> CFU of
 <em>Salmonella</em> of 40 specific-pathogen-free (SPF)
 piglets. Blood and faecal samples were collected for three weeks
 post-infection. Immune response was studied through total blood cell
 counts, production of anti-<em>Salmonella </em>antibody
 and<em> </em>TNF-a, IL-1b, IL-6 and IFN-g cytokines using
 ELISAs and gene expression. Total <em>Salmonella</em> shedding
 for each pig was calculated using the area under the log curve (AULC) over
 three weeks. Pigs were then clustered into high-, intermediate-, and
 low-shedders after hierarchical clustering. Microbiota compositions were
 assessed using 16S rRNA microbial community profiling. Comparisons were
 made between control and inoculated pigs, then between high- and
 low-shedders pigs.