| Duck Tembusu virus is a newly emerged virus in China which was harmful for layer ducks and breeder ducks. It belongs to the genus Flavivirus under the family Flaviviridae, and clustal into Ntayavirus group. It mainly destroyed the reproductive system of duck, making duck have a fever, feed intake and egg production of layer duck and breeder duck resulting in a sharp decline, causing huge economic loss in breed duck industry of China.Nowadays, research progresses have been reported on the profiles of viral physicochemical properties, culture characteristics, pathogenicity, genome and its encoded proteins, while the pathogenesis of the virus is unclear. The response ability of host immune system play a great role in defense of the pathogen invades. The impacts of Tembus virus on the duck immune function had not been reported. In this study, we determined the host immune organ index, antibody levels to some vaccines, T lymphocyte proliferation and relative mRNA expression of immune-related molecules of ducks infected with duck Tembusu virus. Throughout these assay, we want to reveal the impact of duck Tembusu virus infection on the immune response ability of duck, in order to provide fundament for the further research of duck Tembusu virus in viral pathogenesis, immunology, etc. in the future, the results were as follows:1. Immune organ index of infected SheldrakeDuck immune organs were destroyed after infected with duck Tembusu virus, in the early stage of infection (1day-post-infected to3day-post-infected) spleen was enlarged, and the thymus indexes of test group were significantly lower than those of the control group at7day-post-infected (dpi) and10dpi, and bursa atrophy from1dpi to14dpi.2. Vaccine antibody level of infected SheldrakeCompared with only vaccinated vaccine control group, the test group infected with duck Tembusu virus before vaccinated vaccine, antibodies generated delay, reduction in peak antibody, and antibody declined accelerate, and throughout the test period, the antibody levels of the test group were lower than that of only vaccinated vaccine control group. The results showed that the duck Tembusu virus infection could inhibit the ability of humoral immune response to inactivated vaccine and attenuated vaccine of duck.3. T lymphocyte proliferation and transformation ability of infected Sheldrake After duck Tembusu virus infection, compared with control group, peripheral blood lymphocyte stimulation index of test group, presented increasing first and then decreasing, and recovering again. Lymphocyte stimulation index of test group was very significantly higher than that of control group at3dpi (day post-infected), and then decreased to the level of control group at5dpi, and was significantly lower than that of control group at7dpi,15dpi, and recovered to the level of control group at21dpi. The results indicated that duck Tembusu virus infection would significantly inhibit the lymphocyte proliferation and transformation ability of duck from7dpi to15dpi.4. Immune-related molecules mRNA relative expression of infected SheldrakeThis study have used the established duck RLRs and IFN SYBR Green I real-time PCR method to detected the RIG-I, MDA5, IFN-a and IFN-y mRNA relative expression for liver, spleen, lung, kidney, ovary, thymus, bursa seven kinds of tissues of ducks infected with duck Tembusu virus. The results showed that, throughout the test period, the RIG-I, MDA5, IFN-α and IFN-γ mRNA relative expression in tissues of test group have been in a state of vibration, the duck Tembusu virus infection have different degrees of inhibition on the expression of RIG-I, MDA5, IFN-a and IFN-y in the seven detected tissues, and the inhibition degrees were different at different times and different tissues for different immune-related molecules.The tissues that RIG-I, MDA5, IFN-a and IFN-y mRNA expression were inhibited most severe were the ovaries, which is consistent with the clinical phenomenon that duck Tembusu virus mainly destroyed ovarian and caused ovarian lesions, revealing ovarian was the primarily target organ of duck Tembusu virus.In summary, infection with duck Tembusu virus, it would affect the host immune response ability on humoral immunity, cellular immunity and innate immunity in varying degrees, which humoral immunity in the whole test period neither recovered to the level of control group. |
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