Salmonella enterica subsp. enterica serovar Enteritidis Transcriptome or Gene expression. Salmonella enterica subsp. enterica serovar Enteritidis

Salmonella enterica serovar Enteritidis (S. Enteritidis) is the most important cause of bacterial food-borne gastroenteritis world-wide. Despite the remarkable genetic homogeneity within this serotype, field strains of S. Enteritidis show extensive phenotypic diversity and differences in virulence potential in both in vitro and in vivo models. In this study, we used RNA-Seq technique to characterize differences in the global transcritome between several genetically similar but phenotypically diverse poultry-associated field strains of S. Enteritidis grown in laboratory media at avian body temperature (42°C). These S. Enteritidis strains were previously characterized as high-pathogenic (HP, n=3) and low-pathogenic (LP, n=3). Using the negative binomial distribution-based statistical tools, edgeR and DESeq, 252 genes were identified as differentially expressed (DE genes) in LP strains when compared with the HP strains (P<0.05). A majority of DE genes (235, 93.2%) were down-regulated whereas a few genes (17, 6.8%) were up-regulated in all LP strains. We show that LP strains have unique transcriptional profile that is characterized by significantly reduced expression of several transcriptional regulators, and reduced expression of virulence (eg., SPI-1, SPI-5, fimbrial and motility genes) and stress-associated genes involved in protection against osmotic, oxidative and other stresses such as iron limiting conditions commonly encountered within the host. In addition, several functionally uncharacterized genes were down-regulated.