| 摘要 |
PROBLEM TO BE SOLVED: To obtain a mutant of an infectious bursa fabricii's disease virus (IBDV) capable of inducing protective immune response against IBDV strains of a conventional type and an E-type mutant, and a vaccine containing the mutant. SOLUTION: An IBDV mutant containing a nucleotide sequence encoding an E-type mutant VP2 protein in a segment A of a virus genome, and infective and duplicative in CEF tissue culture is produced. The mutant contains one or more mutations in which a codon against the amino acid at the 254th position encodes glycine and/or a codon against the amino acid at the 270th position encodes threonine in a coding region of E-type mutant VP2. The mutant can be used effectively in hens as a live vaccine, or as an inactivated or attenuated vaccine. |
