Rescue of virulent class I Newcastle disease virus variant 9a5b-D5C1
1 College of Veterinary Medicine, Yangzhou University, 48 Wenhuidong Road, Yangzhou, 225009, People’s Republic of China
2 Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, People’s Republic of China
3 China National Engineering Technology Research Centre for Poultry, 2949 Zhennan Road, Shanghai, 200331, People’s Republic of China
Virology Journal 2012, 9:120 doi:10.1186/1743-422X-9-120Published: 18 June 2012
The virulent class I Newcastle disease virus (NDV) variant 9a5b was generated from a nonvirulent NDV isolate Goose/Alaska/415/91 via nine consecutive passages in the chicken air sac, followed by five passages in the chick brain. The evolutionary mechanism of virulence in the class I NDV isolate is not fully understood. To elucidate this evolutionary mechanism, a reverse genetics manipulation specific for class I NDV is indispensable.
A full-length cDNA clone of 9a5b and the helper plasmids pCI-NP, pCI-P, and pCI-L were constructed from segments of cDNA. After these plasmids were co-transfected into BSR T7/5 cells, infectious viral particles were obtained. The rescued viruses were genetically and biologically identical to the parental strain and showed similar pathogenicity in chickens.
A stable recovery method for class I NDV was established. Reverse genetics of the class I NDV variant 9a5b allowed for the generation of genetically altered and virulent NDV, and can be used as a foundation for research on the evolution of virulence in class I NDV isolates.