Research On Expression Of TLR3 And Rig-i Related Factors In Immune Organs Of Duckling Infected By DRV

Duck avian reovirus(DRV) mainly invades immune system of duckling, such as the spleen, bursa and thymus, resulting in immunosuppression and increasing chances of other pathogen infection in infected ducklings. There are a lot of pattern recognition receptors in natural immune system to identify the virus nucleic acids, which can activate the body’s antiviral response. TLR3 and RIG-I can specifically recognize ds RNA or intermediate viral replication and then activate the downstream signaling molecules to induce IFN β release, leading to antiviral immune response. Nowadays we still hvae no ideas about the changes of signaling pathways related genes in the body’s antiviral response when DRV invade into ducklings. In this research, we want to study the m RNA expression levels of TLR3 and RIG-I signaling pathway related genes in ducklings infected DRV through artificial copying animal model and explore mechanism of immunosuppression, we also want to find main antiviral signaling pathways in natural immunity that caused by DRV. The main research content is as follows:1. Preparation for the model of ducklings with DRV(HP20090318 strain)Thirty Cherry valley ducks were random Ly divided into control group and infected group. The ducklings of infected group were inoculated with DRV(HP20090318 strain) about 0.2m L per feather at 7 days while the ducklings of control group were inoculated with equal physiological saline. Three ducklings were killed in every group after 1d、3d、5d、7d、14d inoculated. We found hemorrhage in spleen of ducklings of infected group after 1d and 3d inoculated, necrosis and granuloma in spleen of infected group after 5d and 7d inoculated. The bursa and thymus have no obvious pathological changes in duckings of infected group. Large of red cells found in spleen tissue after infected 3 days and granuloma was found in spleen tissue after infected 7d. Several lymphoid follicles reduce in the bursa the control group have no found pathology changes. The DRV was located in spleen of infected ducklings with prepared anti-virus rabbit serum in 1:500 concentrat by SABC immunohistochemical staining. The data showed that the positivesignals were found in spleen necrosis and perivascular macrophages, implying that the DRV was located in spleen necrosis and perivascular macrophages. RT-PCR detect the S2 gene of DRV, we can found specificity stripe after duckling was infected by DRV at 1d、3d、5d、7d、14d. In the control group have no found specificity stripe.2. Detection the relative expression level of TLR3 and RIG-I signaling pathway related genes(1) In the TLR3 signaling pathway, there were no significant differences in the relative expression level of TLR3 and TRIF at 1d、3d、5d、7d、14d. The relative expression level of TLR3 and TRIF in bursa higher than in spleen and thymus.The relative expression level of IRF3 in spleen and bursa up regular after infected at 3d. The relative expression level go down Between each other days at 5d、7d、14d and in bursa higher than spleen. In the thymus the relative expression level up regular at infected 1d,other days are not obviously(2) The relative expressive level of RIG-I were higher than TLR3, The relative expression level of RIG-I in bursa higher than in spleen and thymus. The relative expression level of the highest day at 3d and 5d.(3) The last signaling molecules is IFN β, leading to antiviral immune response, it is up regular in spleen bursa and thymus. The relative expression level of the highest day at 3d and 5d. The relative expression level in bursa higher than spleen and thymus.Our study show: succeded copy the model of ducklings with DRV(HP20090318 strain), and the main antiviral immune response leading by RIG-I signaling pathways. The relative expression level in bursa higher than spleen and thymus, a tentative inference on this result is that the bursa caused the main functions in antiviral immune response.