| Salmonella enteritidis(SE)is a foodborne pathogenic microorganism that can cause zoonotic diseases.SE can cause diseases such as acute gastroenteritis in young birds,and even cause shock or death.It can infect laying hens around 20 weeks of age or more,causing the level of salmonellosis to spread,infecting the entire colony,and finally through contaminated poultry product(egg or chicken)to infects people.Cleaning and disinfection cannot effectively remove SE on the surface of eggs,which means that SE may be present in the egg contents,and the ovary and oviduct are the main places where SE infection causes egg contamination.In this study,12 SE-negative 24-week old White Leghorn layers were selected as test animals and divided into 2 groups.The test group received SE solution and the control group received an equal amount of sterilized PBS solution.We take samples on the 7th and 14 th days after infection,and measure the immune organ index of layers;determine the colonization of SE in each section of the digestive tract and the oviduct;measure the contents of four cytokines(IFN-γ,TNF-α,IL-2,and IL-18)in serum by ELISA in test group and control group;observe pathological pathology in liver,jejunum,ovary,spleen,oviduct,and pancreatic by paraffin section and HE staining;measure the expression of 9 Toll-like receptor genes in the cecum,oviduct and ovary by quantitative PCR(Q-PCR).In order to understand the effect of SE infection on the structure of intestinal tract and oviduct flora of layers,we use16 S r RNA microbial community composition analysis on the cecum contents and oviduct contents samples of the test group and the control group at two time points.After SE infection in layers,the spleen index of the host was significantly increased,and the levels of IFN-γ,TNF-α,IL-2,and IL-18 in the serum were increased.On the 14 th day after infection,the return of the immune organ index and IFN-γ to normal levels indicates that Salmonella enteritidis activated the host’s innate immunity,and the immune response recovered with the extension of the infection time.The HE staining of some tissues revealed that SE infection caused damage to the digestive,reproductive and immune organs of layers.TLRs’ s Q-PCR results showed that in the cecum,the expression of TLRs in the experimental group increased on the 7th day;in the fallopian tubes,the expression of TLR1 A,TLR5,and TLR7 increased significantly;in the ovaries,the expression of TLR5 and TLR15 significantly increased.It means that the infection of SE increases the expression level of innate immunity-related genes in the host,thereby resisting the invasion of pathogens.In addition,SE infection significantly changed the composition of the host’s intestinal and reproductive’s microbial community composition,and the number of communities in the cecum decreased after infection.Among them,the dominant bacteria in the test group and the control group were both Firmicutes and Bacteroidetes,but compared with the control group,the Firmicutes in the test group was increased,Bacteroidetes was significantly reduced.The composition of the microbial community in the fallopian tubes became complicated,the Faecalibacterium increased significantly,and Bacteroides decreased significantly.This studies will help control SE,maintain oviduct function,and guarantee clean egg production provides a scientific basis. |
PDF Full Text Request