Rescue of virulent class I Newcastle disease virus variant 9a5b-D5C1.
BACKGROUND
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.


RESULTS
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.


CONCLUSIONS
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.
Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, People's Republic of China.
Yang
Y
Yu
Xusheng
X
Qiu
Dan
D
Xu
Yuan
Y
Zhan
Chunchun
C
Meng
Nana
N
Wei
Hongjun
H
Chen
Lei
L
Tan
Shengqing
S
Yu
Xiufan
X
Liu
Aijian
A
Qin
Chan
C
Ding
D000818:Animals; D002645:Chickens; D005777:Geese; D009521:Newcastle Disease / Q000821:virology*; D009522:Newcastle disease virus / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity*; D010957:Plasmids / Q000235:genetics; D059386:Reverse Genetics / Q000379:methods*; D012692:Serial Passage; D014774:Virulence