Study On The Immunosuppressive Mechanism Of Broilers Coinfected With Avian Leukosis Virus Subgroup J And Reticuloendotheliosis Vi

Pathological model was established in commercial broilers at one-day-old that inoculated by avian leukosis virus subgroup J (ALV-J) strain NX0101, reticuloendotheliosis virus (REV) strain SD9901 and ALV-J + REV. Primary study showed that body weight of broilers infected with ALV-J or REV, compared with the control, was significantly depressed and antibody response to NDV vaccine was inhibited. In addition, these broilers were susceptible to bacterial agents, such as colibacillosis, causing higher lethality rate in early time. All that above was even more serious in broilers infected with ALV-J + REV.Apoptosis of lymphocytes in bone marrow, spleen, thymus and bursa was detected by light microscope, electron microscope and terminal- deoxynucleotidyl transferase UIP nick end labeling(TUNEL). The results showed ALV-J could induce incoordinate apoptosis of lymphocytes in thymus, bursa and spleen, which was mainly found in early time(in two weeks). And the apoptosis was much more obvious in thymus than in other immune organs . So it was concluded that the apoptosis of lymphocytes was the main reason that led to atrophy of immune organs and immunosuppression of body.Dynamic changes of histopathology were studied on immune organs and some visceral organs such as liver, kidney, cardiac muscle and lung. The results showed that REV chiefly caused hyperplasia of reticulocytes and lymphocytes in bone marrow while ALV-J mainly conduced hyperplasia of eosinocytes. The lesions of bone marrow in chickens infected with ALV-J + REV were more serious than that infected with REV alone, but different to that infected with ALV-J alone. These data showed that bone marrow was very important in diseases caused by ALV-J or REV. Therefore, lesions of bone marrow was the essential reason making immunosuppression. The materialatrophy in other immune organs, which was related to lesions of bone marrow and apoptosis or necrosis of lymphocytes, being serious when chickens infected with ALV-J + REV then followed by chickens infected with REV alone, was also the important reason for immunosuppression . In others visceral organs, hyperplasia of tumorous eosinocytes in chickens infected with ALV-J and hyperplasia of tumorous reticulocytes with lymphocytes in chickens infected with REV were found around the blood vessel. From the lesions of organs, it could be seen that the immunosuppresion in chikens infected with ALV-J + REV was much more serious than that caused by ALV-J or REV alone, however, it was not found that REV can accelerate the arise of tumors caused by ALV-J in early time.