Patent ID: 7294500

Claim:
A method for obtaining an infectious recombinant very virulent Infectious Bursal Disease Virus (vvIBDV), said method comprising: transfecting at least one first cell, which cell is non-permissive for vvIBDV, with a recombinant nucleic acid comprising a vvIBDV genome; incubating said at least one first cell in a culture medium, so as to produce recombinant vvIBDV which recombinant vvIBDV does not infect said at least one first cell, and which further retains its vvIBDV character; rescuing said recombinant vvIBDV from said at least one transfected first cell or said culture medium; and propagating said recovered rescued recombinant vvIBDV in at least one second cell which is permissive for said vvIBDV.