Patent ID: 7931906

Claim:
An isolated influenza vaccinal virus comprising: (a) an altered PB1 protein, the altered PB1 protein having a substitution at an amino acid residue corresponding to amino acid residue Lys195 of NIBRG-14 PB1 protein (SEQ ID NO: 1), wherein the substitution in the altered PB1 protein is from Lys (K) to Leu (L); (b) an altered PB2 protein, the altered PB2 protein having a substitution at an amino acid residue corresponding to amino acid residue Ser359 of NIBRG-14 PB2 protein (SEQ ID NO: 3), wherein the substitution in the altered PB2 protein is from Ser (S) to Tyr (Y); (c) optionally an altered NP protein, the altered NP protein having substitutions at amino acid residues corresponding to amino acid residues Asn255, Ser410 and Ser446 of NIBRG-14 NP protein (SEQ ID NO: 5), wherein the substitutions in the altered NP protein is from Asn (N) to Asp (D) at amino acid residue 255 and Ser (S) to Phe (F) at amino acid residues 410 and 446; (d) optionally an altered M protein, the altered M protein having a substitution at an amino acid residue corresponding to amino acid residue Leu236 of NIBRG-14 M protein (SEQ ID NO: 7), wherein the substitution in the M protein is from Leu (L) to Phe (F); (e) an altered PA protein, the altered PA protein being selected from the group consisting of a single mutant having a substitution at an amino acid residue corresponding to amino acid residue Tyr465 and a single mutant having a substitution at an amino acid residue corresponding to amino acid residue Glu494 of NIBRG-14 PA protein (SEQ ID NO: 9), wherein the substitution at amino acid residue 465 is from Tyr (Y) to His (H), and the substitution at amino acid residue 494 is from Glu (E) to Gly (G); and (f) an altered NS protein, the altered NS protein being selected from the group consisting of a double mutant having substitutions at amino acid residues corresponding to amino acid residues Leu90 and Leu110 and a deletion mutant having a stop codon at an amino acid residue corresponding to amino acid residue Asn122 of NIBRG-14 NS protein (SEQ ID NO: 11), wherein the substitutions in the NS protein are from Leu (L) to Pro (P) at amino acid residues 90 and 110, wherein the virus exhibits increased proliferation in Vero cells compared to the H5N1 vaccine strain NIBRG-14.