Dynamic Study On Immunopathology Of Cherry Valley Duck Hepatitis Virus Infecting Ducklings And Adolescent Ducks

4-day-old and 35-day-old ducks were inoculated with Jiangxia strain of duck hepatitis virus 1,at 24 h,48 h,72 h,120 h and 168 h PI,pathological changes of live and immune organ,distribution and quantity of IgY~+-cell,TNF-αand cortisol of serum were studied dynamically.The result as followed.The clinical symptoms of infected ducks showed that,some of 4-day-old ducks died 1h after representative symptoms of DVH,and the dead peak time between 24 h to 48 h PI,live,spleen and kidney show pathological changes after dissection; 35-day-old ducks infected show no clinical symptoms and no visible lesions in the offal.Histopathological examination revealed the hemorrhagic and necrotic hepatitis in 4-day-old ducks at 24 h PI.At 48 h to 168 h PI,proliferative inflammation was observed.There was necrosis and infiltration of heterophilic granulocyte in thymus,bursa of Fabricius and spleen.From 48 h to 168 h PI,there was necrotic inflammation in spleen,and thymus,liver,bursa of Fabricius,cecal tonsil and gland of Harder with no obvious lesions in 35-day-old ducks.Structure of the various tissues and organs of 4 and 35-day-old control group ducks were normal.Quantity of IgY~+-cell in immune organs:the quantity of IgY~+-cell increased significantly compared with the control group,from 48 h to 168 h PI;and that in 35-day-old duck had no significant changes at 24 h to 168 h.The content of TNF-αand Col of serum showed that:the content of TNF-αincreased significantly in 4-day-old duck compared with the control group at 24 h PI,and those decreased significantly in 35-day-old duck compared with the control group at 24 h,48 h and 120 h PI;The content of Col increased significantly in 4-day-old duck compared with the control group at 72 h to 168 h PI,and that decreased significantly in 35-day-old duck compared with the control group at 24 h to 48 h PI.Summarized the results,there were hemorrhagic and necrotic hepatitis in 4-day-old ducks PI,the content of TNF-αincreased at this time,so it is closely related to liver damage;and then the content of Col increased,it can reduce immune damage for inhibiting the body's immune levels;added increasing of IgY~+-cell closely related to the humoral immune,concluded the immunity of 4-day-old duck enhancing.From 24 h to 168 h PI,the liver of 35-day-old ducks showed no pathological changes,the content of TNF-αand Col of serum decreased significantly, but the reason and effect were not clear;the quantity of IgY~+-cell in spleen had no significant changes,concluded the immunity of 35-day-old ducks in a normal state.