The Dynamic Changes Of Immunology In Chickens After Inoculation With HVT Vaccine And SEB And After Infection With VMDV

Marek's disease (MD) is a malignant lymphoproliferative disease of chickens caused by MD herpesvirus (MDV) . Although vaccination is remarkably effective in protecting chickens, MD has being a major problem for the poultry industry during the last 50 years. The main reason is the continuous evolution of MDV strains towards increased virulence causing vaccine break. At present, it is known that a new comprehensive mesure that includes vaccine fist place , genetic resistance to disease and biological control second, must be adopted. But the studies in these fields is usually based on the pathogenesis and immunology of MD. The exact mechanisms of immunity induced by MD vaccine remains unknown, because of its complexity. So there are a lot of fundamental studies in the pathogenesis and immunology of MD. Superantigen offered a new pathway in research. Staphylococcal Enterotoxin B(SEB) is a kind of superantigen that has been deeply studied in many aspects. SEB has been used in treatment for many human malignant diseases for a long time. But there are few reports in the literature about the role of SEB in chickens. The demonstration of immunity induced by SEB in chickens, can provide the useful information to develop immunotherapy against not only herpesvirus but also other virus-induced tumor. So it is important for scientists to study MD by superantigen.The aim of this study was to find the dynamic changes of immunology in chickens after inoculation with HVT vaccine and SEB and after infection with vMDV. One day old chickens were randomly assigned to four groups: control group, group of inoculation with SEB, group of inoculation with HVT vaccine and group of inoculation with HVT vaccine and SEB. At 1, 8, 15, 22 and 29 days age, the number of ANAE(Acide nonspecific a-naphthy acetate esterase) positive lymphocytes in peripheral blood was measured. At 2,9, 1 6, 23 and 30 days age, T lymphocytes proliferative activities of spleens and thymuses were measured. At the same time, the amount of nitric oxide (NO) released from macrophages and the activities of acid phosphatase(ACP) in peritoneal macrophages were measured. At 31 days of age, chickens were divided into five groups, the others were infected with MD virus but control group, ie Control/Virus group, SEB/Virus group, HVT/Virus group, HVT+SEB/Virus group. At 42, 60 and 90 days age, the number of ANAE positive lymphocytes in peripheral blood was tested. At 43, 61 and 91 days age, T lymphocytes proliferative activities of spleens and thymuses were measured. At the same time, the amount of NO released from macrophages and the activities of ACP in macrophages were measured. The study suggested that SEB can increase the amount of ANAT+T and strengthen T lymphocytes activities in spleens and thymuses and enhancecell-mediated immune responses. Similarly, SEB can increase the amount of NO and the activation of ACP in the non-specific immune responses. After infection with vMDV, specific and non-specific immune responses in HVT+SEB/V group was higher than the immune responses of other groups, such as SEB/Virus group, and HVT/Virus group. So there was very strong ability to anti-infection of vMDV in chickens of HVT+SEB/V group. It was suggested that there are cooperation between SEB and HVT vaccine in immune responses. They play an important role at anti-infection of vMDV in chickens.Through the preliminary study on the role of SEB in chickens, it can be postulated that SEB can be used as a treatment and prevention method against some avain diseases.Candidate: ChenXi Speciality: Preventive Veterinary MedicineSupervisor: Prof. WeiPing...