The Changes Of Immune Performance In Early Enteritis Salmonella Infected Chickens And Genome-wide Methylation Regulation Analysis

Salmonella enteritidis (SE) is a zoonosis, which not only bring huge economic losses of Poultry rearing, but also do harm to dairy industry, Public health and food safety. Due to through both horizontal and vertical transmission, it is requiring efforts to prevent and control the disease. At present, it can be prevented by incubating vaccines and antibiotics, but the effect is not perfect. Resistance Breeding is a practical way to solve the problem above. But disease resistance is dependent on long term process of natural selection and premonition is generally quantitative traits influenced by a large number of genes which make it difficult to cultivate the disease resistance strain. To data, Salmonella enteritidis resistance researches mainly focus on TLR4/MyD88/NF-x B. However, very few researches focus on disease resistance in epigenetics field. In this study, the tested avain were infected artificially by the SE, the changes of body temperature, body weight and immune indexes were tested and the expression of related genes in caecum were analyzed by real-time fluorescent quantitative PCR, at the same time, change of genome-wide methylation was assayed by MeDIP-seq, aiming to explore the infection mechanism of SE early infection and and provide the genetic basis for improving the efficiency of breeding for SE-resistance.Experiment1:12-day-old White Leghorn chickens were sampled and infected with Salmonella Enteritidis. Collected samples respectively at12hpi,24hip,72hpi and144hpi after infection and simultaneously detected the changes of body temperature, weight and immune organ index. Detected the changes of serum medium IFN-a, IL6, TNF-a, and IgY through enzyme-linked immunosorbent assays (ELISA). Used probe and plate count methods to detect bacterium capacity in blood, spleen and caecum. The expression levels of TLRs genes(TLR4, TLR2-1, and TLR21) and methyltransferase genes (DNMT1, DNMT3A and DNMT3E) were detected by real-time fluorescent quantitative PCR. SE infectted24h, spleen index, bursal index, IFN-a in serum, IL6in serum and the expression of TLRs gene were different between SE group and Control group (P<0.05). The results indicate24h may be an key time in SE early infection.Experiment2:Based on the data of Experiment1and the results of methylation of the whole genome, selected3dying chickens from the SE group after24hpi of infection as the study subject while setting a controlled group with3chickens. Sampled blood, extracted DNA and then analyzed samples by MeDIP-seq. Used the peak whose P<0.05as the difference peak we successfully obtained954differential gene. We find53differential signaling pathways. The core promoter regions of genes usually distributed within the upstream2kb region and the methylation of this region would affect genes expression levels.229difference peaks fell into this region. According to the gene functional query (http://www.genecards.org) and related literatures we found AGAP3, BF1, MR1, VPS37D, CD8A, TLR2-1, DNMT3A, MIR365-1and MIR365-2which have relations with inflammation or cancer.