ATTENUATION OF INFECTIOUS BURSAL DISEASE VIRUS BY SERIAL PASSAGE THROUGH CHICKEN EMBRYONATED EGGS AND CHICKEN AND DUCK EMBRYONIC FIBROBLASTS
1978 Volume 28 Issue 1 Pages 41-45
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1978 Volume 28 Issue 1 Pages 41-45
To obtain an avirulent strain for chickens, infectious bursal disease(IBD) virus was subjected to serial passages up to the 25th passage through chicken embryonated eggs (CE), chicken embryonic fibroblasts (CEF), or duck embryonic fibroblasts (DEF). As a result, it became attenuated only by CE-passage. The strains of IBD virus obtained at the 25th passage were materially the same in virulence for CE, judging from the induction of death and hemorrhage of the embryo. The attenuated virus obtained by CE-passage however, seemed to be more virulent than that obtained by passage through CEF or DEF, indicating the adaptation of the attenuated virus to CE.
Lines of precipitate were formed by agar gel immunodiffusion between IBD viral antigen and serum samples collected from chickens inoculated with the CE-passage virus. They appeared to decrease gradually in number with the progress in passage. Finally, all the samples collected from chickens inoculated with the attenuated virus developed a single precipitation line. On the contrary, some serum samples collected from chickens inoculated with the virulent virus still produced more than one line.
