Abstract: Cellular attenuated strain of infection bronchitis H₁₂₀ strain(IBH₁₂₀)was cultured successfully with virus which cultured on the chicken embryo.Atypical Coronary viral partical were observed by electric microscope.IBH₁₂₀ cellular attenuated strains were negative after examination bacterium,mildew,mycoplasma,chicken leukemia virus,moreover,they speciticity of IB virus.Virus proliferate could reach peak after 48 h.When CEF cells infected with IBH₁₂₀,TCID₅₀ of C₄-C₁₀ generation of H₁₂₀ strain cellular attenuated virus rose gradually and stabilized with increasing generation.TCID₅₀ of C₄-C₁₀ generations were between 10^7.35 and 10^8.0.but EID₅₀ of C₅-C₁₀generation were degressive trend.The variational range was between 10^7.3 and 10^6.5.Theimmunogenicity of IBH₁₂₀ cellular attenuated virus was checked.The result demonstrated that three days old chickens were inoculated in nose with 10^3.5 TCID₅₀ and 10^4.5 TCID₅₀ of C₄,h,C₁₀ generation virus in each chicken respectively,their protection rate was between 80% and 100%.The virus separation recovery rate was 20% and 0 respectivelly.

Key words: Cellular attenuated strain of IBH₁₂₀, Breeding curve, Immunogenicity, Immune protection rate

CLC Number: 

• S436.612