Abstract: An observation of efficacy of bivalent live IBD vaccine was conducted using SPF chicks.The chicks were vaccinated at 14 days of age with the bivalent vaccine and a live intermediate strain BJ836 vaccine and challenged 14 days later at different doses(1∶1,1∶10 or 1∶100)of either a standard serotype I virulent IBDV strain CJ801 or a virulent variant of IBDV strain 1084A.The vaccinated group with the bivalent vaccine acquired complete protection against the challenges by the very high dose(1∶1)of strain CJ801 and the high dose(1∶10)of strain 1084A,but had poor protection against the challenges by the very high dose(1∶1)of strain 1084A.The vaccinated group with the BJ836 vaccine acquired complete protection against the challenges by the high dose(1∶10)or strain CJ801 and the low dose(1∶100)of strain 1084A,but had poor protection against the challenges by the very high does(1∶1)of strain CJ801 and the high dose(1∶10)of strain 1084A.This showed that the bivalent vaccine had significantly better protection against the challenges of standard serotype I virulent IBDV strain and virulent variant IBDV strain in comparison with conventional type I IBD vaccines.

Key words: Bivalent live IBD vaccine, Live intermediate strain BJ836 vaccine, Protection

CLC Number: 

• S858.31