Abstract
Background: Infectious Bursal Disease (IBD) is a highly contagious disease characterize by severe damage of the bursa of fabricious and immuuosupperssion. The current study is aimed to evaluate the protective efficiency of IBDV specific IgY-antibodies prepared against the disease. Materials and Methods: Twenty white Leghorn laying hens were immunized with Infectious Bursal Disease Virus (IBDV) vaccine. Blood samples and eggs were collected simultaneously from laying hens before immunization and every 2 weeks after primary immunization. The collected eggs were used for separation of the yolk and extraction of IgY-antibodies by ammonium sulphate-caprylic acid method. Results: The mean log(10) antibody titer of the serum samples showed significant increase after 2 weeks of immunization and reached its maximum level after 6-8 weeks from the primary immunization. Egg yolk IgY-antibodies level increased after 4 weeks of immunization and reached its maximum level after 8-10 weeks of immunization. Evaluation of the protective value of IBDV-specific lgY-antibodies revealed reduction in morbidity and mortality rate in challenged chickens 15 and 10%, respectively as compared with 90% morbidity and 40% mortality in non-immunized challenged chickens. In chicken group actively immunized with IBDV vaccine (live and inactivated), the morbidity and mortality rates were reduced to 10 and 5%, respectively, following challenge with virulent IBDV. However, when IBDV specific IgY-antibodies were used simultaneously with IBDV vaccines the morbidity and mortality rates were reduced to zero. Conclusion: The IBDV specific IgY-antibodies can be used simultaneously with IBDV vaccines for controlling the disease as the morbidity and mortality rates can be reduced to zero.