Differential immunological response detected in mRNA expression profiles among diverse chicken lines in response to Salmonella challenge

Abstract

Salmonella enterica serovar Enteritidis is a bacterial pathogen that contributes to poultry production losses and human foodborne illness. The bacterium elicits a broad immune response involving both the innate and adaptive components of the immune system. Coordination of the immune response is largely directed by cytokines. The objective of the current study was to characterize the expression of a select set of cytokines and regulatory immune genes in three genetically diverse chicken lines after infection with S. Enteritidis. Leghorn, Fayoumi and broiler day-old chicks were orally infected with pathogenic S. Enteritidis or culture medium. At 2 and 18 h postinfection, spleens and ceca were collected and mRNA expression levels for 7 genes (GM-CSF, IL2, IL15, TGF-β1, SOCS3, P20K, and MHC class IIβ) were evaluated by real-time quantitative PCR. Genetic line had a significant effect on mRNA expression levels of IL15, TGF-β1, SOCS3 and P20K in the spleen and on P20K and MHC class IIβ in the cecum. Comparing challenged vs. unchallenged birds, the expression of SOCS3 and P20K mRNA were significantly higher in the spleen and cecum, while MHC class IIβ mRNA was significantly lower in spleen. Combining the current RNA expression results with those of previously reported studies on the same samples reveals distinct RNA expression profiles among the three genetic chicken lines and the 2 tissues. This study illustrates that these diverse genetic lines have distinctively different immune response to S. Enteritidis challenge within the spleen and the cecum.