Pathological Evaluation Oninactivated Vaccine Of Ducks Hemorrhagic Ovaritis

Duck Hemorrhagic Ovaritis (DHO) is an acute duck hemorrhagic infectious disease caused by flavivirus. For the great damages to the duck breeding industry by DHO, it becomes one of the most serious diseases that threaten the breeding industry.To explore how the constructed vaccines have protective effects on the ducks infected artificially, we put the36Peking ducks into B1control group,A2immuned group and A3immuned group randomly,1ml cell vaccine per duck injection for A2immuned group and the same dose of04batch vaccine per duck injection for A3immuned group(both were pectoral muscle injection). Vaccinate for the second time14days after the first vaccination.23days after the second injection, B1control group, A2and A3immuned groups were challenged by the fourth generation GHO-HB virus (injection under pectoral muscle skin, ELD50=10-5.7/0.1ml,1ml per duck).3ducks in each group were killed randomly5days after challenged and all the left ones were killed9days after challenged. During the period, blood, clinical observation, histopathology observation and immunohistochemistry were took.The results showed that antibody titers were very low in all three groups.There was no virus isolation in both immuned groups and that in control group was83%.We have observed that there was no clinical symptoms,less pathological changes, no hyperplasia of mesenchymal cells,infiltrate of lymphocytes and monocytes in liver around the portal tract area and increased lymphocytes in spleen in immuned groups.however,leg weakness, paralysis,high body temperatures,depression,weight loss and green watery defecation were all observed in the control group. Histopathological observation was DHO, interstitial hepatitis and nonsuppurative encephalitis. Immunohistochemistry examination results showed that virus replicated mainly in cytoplasm and theca folliculi, fallopian to be testicles, spleen, liver, kidney, he-art and brain were the main target organs of DTMUV (Duck Tembusu Virus).The study evaluated the immunization effects of the vaccines against DHO that developed by Institute of Animal Sciences (IAS), Chinese Academy of Agricultural Sciences (CAAS).Results showed that all the immuned ducks were protected well clinically.We observed there were a certain degree but low level of damages in immuned duck organs and the growth of immune organs were in good situation.But typical DTMUV infectious symptoms appeared in control group. Antigen concentration in control and immuned groups organs showed that positive rate of DTMUV is lower and DTMUV distributed in smaller range in immuned groups than in control group.as a whole, the vaccines can stimulate immune organs, strengthen immune system and protect all tissues and organs from damages when low dosage of vaccines are injected into the experimental ducks.Our study is helpful for the development of modern vaccine.