IBDV超强毒GX8/99株细胞适应毒及其鸡体回传毒的致病性、免疫原性比较

The Comparison of the Pathogenicity and Immunogenicity of the Cell-adapted Virus and SPF-chicken-passaged Virus of the vvIBDV Strain GX8/99

传染性法氏囊病病毒(Infectious Bursal Disease Virus,IBDV)的超强毒株GX8/99经在鸡胚成纤维细胞(CEF)上连续传代22代后,细胞适应毒株GXC23对鸡的致病性显著减弱,对4～6周龄SPF鸡的致死率从85%～90%,减为0～5%。将GXC23在96孔细胞培养板上经两次无限稀释法得到3个克隆病毒。在SPF鸡回传20代后,相应的毒株GX-2B20、GX-4B20、GX-5B20,对SPF鸡的致死率仍维持在0～5%。回传23代后,GX-2B23,GX-4B23免疫2周龄SPF鸡,3周后虽然能引起法氏囊一定程度的萎缩及点状出血,法氏囊髓质区淋巴细胞坏死和变性,而且,仍表现出明显的免疫抑制性,都能造成新城疫,禽流感(H9-和H5-)疫苗抗体水平的显著降低。但是二者却都可以诱导机体产生很高的抗体水平,可抵抗超强毒GX8/99的人工感染,保护率可达100%。

The GX8/99, a strain of very virulent Infectious Bursal Disease Virus （vvlBDV）, has been developed in CEF cell for 22 generations, and has been attenuated after adapting to the CEF cell. The mortality of the 4 - week-age SPF chicken has decreased from 85% -90% to 0 -5%. And when the cell -cloned virus, GX - 2B20, GX -4B20 ,GX -5 B20, were returned to SPF -chicken, the pathogenicity did not increased, the mortality was also 0 - 5%. In order to research the immunogenicity of the backpassaged virus, we immuned the 2 -week - age SPF chicken with GX - 2B23 ,GX - 4B23, and infected the vvIBDV GX8/99 after 3 weeks. The results show that both of them could make the bursal atrophic and decrease the antibody degree of the NDV and AIV （ H9 -, H5 - ） vaccine significantly. But they both have very good immunogenicity, the protective rate was 100%.