Abstract: SPF chickens were inoculated with four commercial IBD live vaccines named A, B, C, D respectively, to assess the immune effect of different vaccines by challenged with IBDV. 10 days old SPF chickens were divided into different groups and were inoculated with A, B, C, D vaccines a feather copy each chicken, challenged with vvIBDV (GD0104) 1000 LD₅₀ doses each chicken, the protection rate of each vaccine group that challenged at 21 days old were 100%, 85%, 100%, 100%; the protection rate of each vaccine group that challenged at 35 days old were 100%, 75%, 95%, 100%. Antibody tests showed that the level of antibody titers D>A>C>B; the rate of antibody turn positive: A>D>C>B; immune stress effect: A, D>B, C. Considering of the indicators change post-infection vaccination, A and D vaccines are better than the other two live vaccines, can provide effective protection for the SPF chickens.

Key words: IBD; live vaccine; immune effect