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Effects of Salmonella enterica serovar Enteritidis pathogenicity island ROD21 on the expression of virulence genes

ABSTRACT: Salmonella enterica serovar Enteritidis (SEn) is a pathogenic Gram-negative bacterium, which possesses several Pathogenicity islands (PAIs), including ROD21, an excisable PAI that has been linked to virulence in mice and poultry. Previous studies from our laboratory have shown that deletion of ROD21 can affect the virulence of SEn. We observed that both the deletion of ROD21 and the joined deletion of SEN1970 and SEN1998 have an impact on the transcriptional pattern of SEn in vitro. We observed changes in the transcription of genes located in SPI-2, which are required for intracellular survival and colonization. We also found that in both cases, genes related to the expression of flagellar machinery are downregulated, which could also be observed in the bacterial morphology in vitro. This observation was later backed up with in vivo experiments in mice, which showed a differential capacity of SEn ROD21 mutant strains to reach levels of colonization at later stages of infection, compared to the wild-type SEn strain. These results have led us to conclude that the deletion of ROD21 genes produces transcriptional changes relevant for the pathogenicity of SEn and its effective colonization in vivo, arguing for possible changes in the genome structure when these genes are deleted, which could affect transcription.

ORGANISM(S): Salmonella enterica subsp. enterica serovar Enteritidis

PROVIDER: GSE342933 | GEO | 2026/08/11

REPOSITORIES: GEO

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	GSE342933_All_samples_raw_counts.xlsx	Xlsx

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Project description:Salmonella Enteritidis is the major food-borne pathogen primarily causing human infection through contaminated chicken meat and eggs. We recently demonstrated that S. Enteritidis strains from poultry differ in their ability to invade human intestinal cells and cause disease in orally challenged mice. Here we hypothesized that the differential pathogenicity of S. Enteritidis strains is due to the differential fitness in the adverse environments that may be encountered during infection in the host. The response of a panel of six S. Enteritidis strains to acid stress, oxidative stress, survival in egg albumen and the ability to cause infection in chickens were analyzed. This analysis allowed classification of strains into two categories: stress- sensitive and stress- resistant, with the former showing significantly (P<0.05) reduced survival in acidic (gastric phase of infection) and oxidative (intestinal and systemic phase of infection) stress. Stress-sensitive strains also showed impaired intestinal colonization and systemic dissemination in orally inoculated chickens and failed to survive/grow in egg albumen. Comparative genomic hybridization microarray analysis revealed no differences at the discriminatory level of the whole gene content between stress-sensitive and stress-resistant strains. However, sequencing of rpoS, a stress-regulatory gene, revealed that one of the three stress-sensitive strains carried an insertion mutation in the rpoS resulting in truncation of σS. Finding that one of the stress-sensitive strains carried an easily identifiable small polymorphism within a stress-response gene suggests that the other strains may also have small polymorphisms elsewhere in the genome, which likely impact regulation of stress or virulence associated genes in some manner. To determine if the differential stress response and virulence observed in this study could be due to the differences in the gene content between different strains, we compared the genomes of all the strains using CGH microarray designed based on the genomic information available for the sequenced strain. All strains (n=6) were hybridized in triplicate.

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Effects of Salmonella enterica serovar Enteritidis pathogenicity island ROD21 on the expression of virulence genes

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