The Apoptosis Of Lymphocytes From Chicken's Thymus And Bursa Induced By Newcastle Disease Virus F48E8 In Vivo

Light microscope and transmission electron microscope and electrophoresis analysis of DNA fragmentation and terminal deoxynucleotidyl transfers (TdT) dUTP nick end labeling (TUNEL) were used to study the apoptosis of lymphocytesfrom chicken's thymus and bursa which were induced by Newcastle disease virus(NDV)-F48E8 in vivo. The results showed that the lymphocytes of chicken's thymusand bursa exhibited obvious apoptosis. Some lymphocytes of thymus and bursa were fragmented into several condensed and round pieces which we could observe underlight microscope. The apoptosis of lymphocytes in chicken's thymus and bursa was observed under transmission electron microscope. The results showed that apoptotic lymphocytes underwent a series of morphologic changes:the chromatin condensed and marginated, and the nuclei appeared crescent, "c" -shaped, petal-like, ring-like, or dark round;and gradually the apoptotic lymphocytes became apoptotic bodies;and finally the apoptotic lymphocytes and apoptotic bodies were phagocytosed and eliminated by thymus Terminal macrophages. Deoxynucleotidyl transfers (TdT) dUTP nick end labeling (TUNEL) was used to detect apoptotic lymphocytes.The apoptotic lymphocytes were observed in infected thymus and bursa lymphocytes, while control thymus and bursa lymphocytes showed little apoptosis or not. DNA extracted from NDV-infected chicken thymus and bursa displayed the characteristic laddering pattern of DNA fragmentation. The results of biostatistic analyses suggest that apoptosis is highly significant in treatment group more than in control group (P<0.01).Theresults were demonstrated that NDV-F48E8 could induce obvious apoptosis oflymphocytes from chicken's thymus and bursa in vivo. It suggest that NDV-inducedimmunospuppression may because by the activation of apoptosis in chicken thymus and bursa lymphocytes. According to the results, we could predict that the apoptosis induced by NDV would be one of the major results of decrease of the numbers and dysfunctions of lymphocytes in NDV-infected chickens.