B亚型禽白血病病毒所致免疫抑制条件下共感染禽波氏杆菌对雏鸡的影响

选择B亚型禽白血病病毒（ALV-B）感染雏鸡造成免疫机能低下,建立免疫抑制模型,以探索免疫抑制条件下共感染禽波氏杆菌后对雏鸡致病性的影响。设计了ALV-B单独感染组,B.avium单独感染组,ALV-B和B.avium共感染组,空白对照组,并且比较相互之间的差异。通过对雏鸡免疫学指标、生长性能及病毒血症和排毒状况的检测,对二者混合感染雏鸡的影响进行了研究。结果显示,ALV-B和B.avium共感染能引起雏鸡的免疫力低下,表现为免疫器官的发育、抗体的产生、淋巴细胞的转化、IL-2和IFN-γ的合成和分泌等受到明显抑制;混合感染组延长了B.avium的病程,增强其对雏鸡的致病性;同时机体出现明显的生长迟滞现象,尤其是第5周龄,共感染组平均体质量仅相当于对照组的40%。结果表明,ALV-B和B.avium在雏鸡体内的增殖方面起协同作用,从而促进了病原在鸡群间的散播;而B.avium对ALV-B导致的病毒血症有一定的抑制作用。在ALV-B免疫抑制作用下,B.avium对雏鸡的致病性显著增强。

Effect of pathogenicity of Bordetella aviumunder immunosuppression induced by avian leukosis virus in chickens

In recent years,co-infection with avian leukosis virus（ALV）and other pathogens has become increasingly severe in the poultry industry in China.To evaluate the pathogenicity of B.aviumunder immunosuppression condition,chickens were injected with either subgroup B ALV（ALV-B）and Bordetella avium,or B.avium,or ALV-B only,and compared the differences between them.By detecting the relevant indices,we analysised the influence of co-infection on growth and immunity of chicks.We found that the group co-injected with ALV-B and B.avium exhibited significant inhibition of the immune function,mainly showing inhibitory effects on the development of immune organs,production of antibodies,transformation of lymphocytes,synthesis and secretion of IL-2and IFN-γ.The co-infection of B.aviumand ALV-B prolonged the course of the disease and increased pathogenicity compared with the group injected with B.aviumonly.Significantly retarded growth was seen in the co-infection group,especially on day 35,the average body weight of the co-infection group was 40% of the control group.Overall,under immunosuppression induced by ALV-B,the pathogenicity of B.aviumwas increased significantlly.This study showed that ALV-B and B.aviumhave synergistic effect in chickens,and promoted the spead of pathogeny,and B.aviumhas inbibitional effect to viremia caused by ALV-B.Our study provide the theory basis for the secondary infections under immunosuppressionin practice,it suggested that we should pay more attention to the secondary infections under immunosuppression induced by immunosuppressive viruses.