Rosenberger JK, et al. Use of infectious bursal disea se virus variant vaccinein broilers and broiler breeders. In: Proceedings of the 36th Western Poultry Diseases Conference. Califonia, 1987, 105~109.
[8]
Jack D J, Sa if, YM . Antigenic diversity of infectious bu rsal disease viruses, Avi Dis, 1987, 31:766~770.
[9]
Ismail NM , S ai,f YM . Immunogenicity of infectious bursal disease viruses in chickens, Avi Dis, 1991, 35:460~469.