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Gene expression responses to a Salmonella infection in the chicken intestine differ between lines.

ABSTRACT: Poultry products are an important source of Salmonella enterica. An effective way to reduce food poisoning due to Salmonella would be to breed chickens more resistant to Salmonella. Unfortunately resistance to Salmonella is a complex trait with many factors involved. To learn more about Salmonella resistance mechanisms in young chickens, a cDNA microarray analysis was performed to compare gene expression profiles between a Salmonella susceptible and a more resistant chicken line. Newly hatched chickens were orally infected with S. enterica serovar Enteritidis. Since the intestine is the first barrier the bacteria encountersbacteria encounter after oral inoculation, gene expression was investigated in the intestine, from day 1 until day 21 post infection. Differences in gene expression between the susceptible and resistant chicken line were found in control as well as Salmonella infected conditions. In response to the Salmonella infection, the expression of different sets of genes seemed to be affected in the jejunum of the two chicken lines. In the susceptible line this included genes that affect T-cell activation, whereas in the more resistant line, at day 1, macrophage activation seemed to be more affected. At day 7 and 9 most gene expression differences between the two chicken lines were identified under control conditions, indicating a difference in the intestinal development between the two chicken lines which might be linked to the difference in Salmonella susceptibility. The findings in this study have lead to the identification of novel genes and possible cellular pathways of the host involved in Salmonella susceptibility. Keywords: timecourse, disease

ORGANISM(S): Gallus gallus

PROVIDER: GSE3066 | GEO | 2005/12/05

SECONDARY ACCESSION(S): PRJNA93159

REPOSITORIES: GEO

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Project description:Campylobacter jejuni (C. jejuni) is a zoonotic pathogen that causes human diarrhea worldwide. Chickens are a natural reservoir of C. jejuni. Understanding the host response to C. jejuni infection at the molecular level will lay the foundation to control human campylobacterosis by reducing food contamination. Two distinct genetic lines, resistant (line A) and susceptible (line B) to C. jejuni colonization, were utilized to profile the host response to C. jejuni infection using an Agilent chicken 44K microarray. Day-old chickens were challenged orally with C. jejuni and spleens collected for total RNA 7 days post-challenge. Twenty infected samples with highest (a) or lowest bacterial number (b) in cecal content and twenty non-infected (c) in each line were randomly pooled into four biological replicates. The pair comparisons among these three groups within each line were analyzed. The signal intensity of each gene was normalized using LOWESS method. A mixed model was used to identify differentially expressed genes by SAS (P < 0.001). This was opposite to previous cecal tonsil microarray result. There were 468, 743, and 939 genes differentially expressed between groups a and c, groups a and b, and groups b and c in line A, respectively, and 201, 37, 126 genes in line B, respectively. More differentially expressed genes in spleen in line A than in line B were found. The results indicated that significantly different response to C. jejuni infection occurred between resistant and susceptible chicken lines, and the effects of interaction between genetics and tissue should be considered. Chickens in two broiler lines were inoculated with 10^5 cfu C. jejuni on one day after hatch. The cecal content and cecal tonsil was collected and bacterial number in cecal content was counted on day 7 after inoculation. Twenty samples were separated into 3 groups (high burden, low burden, and control) based on bacterial burden of cecal content in each line, 5 samples were mixed randomly into one pool. A dual color, balanced design was carried on for all samples. Three comparisons were used in each line, non-infected/susceptible, susceptible/resistant, resistant/non-infected, totally, four biological replicates in each line. A Dye swap was used in each pair of comparisons including AN/AS, AS/AR, AR/AN; BN/BS, BS/BR, and BR/BN. Background subtracted signal intensity were collected from 24 arrays and normalized for data analysis.

Project description:To determine the transcriptional response to Salmonella enterica serovar Enteritidis (SE) infection, a newly developed chicken 44K Agilent array was used to analyze total RNA of heterophils from SE-resistant (line A) and SEâsusceptible chickens (line B), treated with in vitro infection of SE (I) or non SE medium (N) for 1 hr. A dual-color balanced design was used to provide a direct comparison between SE-infected and non-infected groups (AI/AN, BI/BN) and between line A and line B (AN/BN, AI/BI). Data retrieved from 426 immunologically important genes were used for functional analysis. The results indicated that: In the comparisons of SE infection with non-infection, 39 genes were found differentially expressed (P < 0.05 with at least 2-fold) after Salmonella infection, while 21 genes were found differentially expressed between different lineages. Numerous of members in Toll-like receptor (TLR) signaling pathway were identified which include receptors: MD-2, TLR-4, -5, -15; adaptors: TLR adaptor molecule1 (TICAM1/TRIF), MAP kinase kinase 3 (MKK3) and NFkB-1, as well as cytokines, chemokines and costimulatory molecule: interleukin (IL)-1Î², IL-6, IL-8, IL-12, chemokine (C-X-C motif) ligand 1, chemokine (C-C motif) ligand 4, CCL 5, and CD80. Most of immune genes were up-regulated after SE infection, and the magnitude of up-regulation was higher in line A than line B in general. The results suggested that a similar TLR regulatory network exists in both lines with strong response in resistant line. This finding has laid the foundation for further study of molecular and cellular modulation of SE infection in chickens. Keywords: disease state analysis A dual color, balanced design was carried on for all of heterophils samples from sixteen chickens. Each sample type (AI, AN, BI and BN) includes four biological replication for labeling. A Dye swap was used in each pair of comparisons including AI/AN, BI/BN, and AI/BI, and AN/BN. Background subtracted signal intensity were collected from 16 arrays and normalized for data analysis.

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Gene expression responses to a Salmonella infection in the chicken intestine differ between lines.

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