Abstract: The attenuated cell-culture vaccine of avian infectious bronchitis H₁₂₀ virus wassuccessfully prepared. Immune trials carried out in nearly 400 thousand chicks with the vaccine in and out of the laboratory indicated that the immunity was obtained in 4 to 12 day-old chicks 7 days after vaccination at a dose of 0.01 ml each by the way of nasaldrop,eyedrop or drinking-water,and that the protection rates of 88.7% ,87.5% and 87.5% were respectively provided for the chicks,which were inoculated for 17,32 and 60 days,while they were challenged with the standard virulent IBV. The immune protection period of the vaccine for chicken was two months. No harmful effect was observed in the 4 to 12 days-old chicks within 15 days after inoculation with 10 immune doses of the vaccine. The minimum immune dose of the vaccine is 0.001 ml per chick. The vaccine is stored at-20℃ for half a year or at 4℃ for one month and the effect is not weakened.

Key words: Avian infectious bronchitis, H₁₂₀ virus, Vaccine, Whole-chicken-embryo cell culture