Establishment of Pathogenesis Model of Duck Tembusu Virus Disease and the Determination of Duration of Antidody
|School||Nanjing Agricultural College|
|Course||Preventive Veterinary Medicine|
|Keywords||duck Tembusu virus challenged antibody protection threshold immuneduration|
Since april,2010. The provinces:Jiangsu, Zhejiang, Fujian, Anhui, Jiangxi, Hebei…etc occurred a kind of laying egg rate in duck, the feed intake was droped down obviously, symptoms appeared encephalitis, nerve disordered like infectious disease. The research indicate that it is a different pathogen causing the disease and publish a new kind of yellow virus, was " Tembusu virus " The infection rates of up to100%, Morbidity and mortality from5%to30%, egg production rate decreased at40%～50%, causing huge economic losses to the ducks and geese farming. In order to study the pathogenesis of the disease, the experiment was established the incidence model; In order to better prevent and control the outbreak of the disease, the research carried out challenging protection test, the duration of the monitoring of immune antibodies.35-days of non-infectious Tembusu virus in168ducks were randomly divided into7groups, each group has24ducks, of1-6groups with different doses of goose origin Tembusu virus JS804strain were challenged by intramuscular, control group intramuscular injection of the same dose of PBS solution, daily observation of clinical symptoms after challenge, seperately after challenging2d;4d;6d;8d;13d;20d, each group were randomly selected four challenge ducks for killing, two parts in each organic samples were taken per duck, a part was keep in-20℃, for nested RT-PCR detection of virus, anothor was fixed by formalin4%, use for immunohistochemical analysis and HE staining pathological changes. Clinical symptoms observed:Test duck after challenging8d typical Tembusu virus syndrome. Pathological change:major organ lesions, among spleen, liver, the most obvious in brain. Nested RT-PCR results:Challenge after8d of each organ infected virus positive rate was highest, in different organs, spleen was detected the highest rate, by the different challenged group detection, determined duck Tembusu virus disease attack amount is1.6×106TCID50. HE staining pathological observation:Hepatocyte vacuolar degeneration, necrosis, lobule structure damage; spleen lymphocytes degeneration, necrosis, red, white pulp ill-defined. Immunohistochemical localization of discovery:Cardiac fibroblasts, splenic white pulp area, alveolar epithelial cells, tubular epithelial cells, cerebrovascular endothelial cells, liver cells were brown positive signal.14-days-old of non-infectious Tanbusu virus in50ducks were randomly divided into5groups, each group has10ducks, of1-4with different antigen content Tembusu inactivated vaccine intramuscular immunization, control group intramuscular injection of the same dose of PBS solution.21days after immunization, the blood was collected, determination of antibody levels in every ducks, the JS804strain of virus the challenged amount (1.6X106TCID50) was determined using the chapter2test goose origin Tanbusu challenged, the8days after the attack of the poison culling of all the test duck, nested RT-PCR assay duck spleen Tembusu virus. The result:The valence of antibody was29, the challenge of immune protective rate of88.9%, the protective antibody of the duck infected Tanbusu virus critical value of29; simultaneously confirmed the minimum immunization amount of the inactivated vaccine is3.8×105TCIDso.23-days-old of non-infectious Tembusu virus in30ducks were randomly divided into3groups(Single immunization groups, the two immunization groups, control group).the blood collection and determined the valence of antibody. The result:Strengthen immunohistochemistry results were better than single immunization.23-day-old of non-infectious Tembusu virus in30ducks were randomly divided into1,2groups (immune and control group),54-day-old of non-infectious Tembusu virus in30ducks were randomly divided into3,4groups (immune and control group),determination of antibody titers after immunization regularly monitoring the maintenance phase. The result:Effective antibody lasted more than six months and no significant difference in the two-day-old immunization duck.