Comprehensive Evaluation of Infectious Bursal Disease Vaccine Candidate According To the Current Industry Standards - Abstract
Vaccination of chickens using live attenuated vaccines is still the principal method used for control and prevention of infectious bursal disease (IBD) in chickens. All aspects of development, production, quality control and use of modern vaccines are comprehensively regulated by the national and trans-national guidelines. Detailed in vitro characterization, safety and efficacy of a new live attenuated vaccine against IBD was evaluated in this work in compliance with the current European Union regulations. In vitro characterization confirmed that the vaccine strain belongs to intermediate strains with high degree of homology with the existing vaccine strains of the same virulence. General safety of the vaccine was demonstrated in specific pathogen free (SPF) and seropositive chickens. No significant immunosuppression against immunization with live Newcastle disease vaccine was detected in birds previously vaccinated with the IBD vaccine candidate. Vaccine virus was able to spread at least 3 times from vaccinated to naive chickens, without inducing morbidity and mortality. A single amino acid
change at position H253Q was detected in the VP2 gene after 5 in-vivo passages. Complete protection against challenge with very virulent IBD virus was demonstrated in laboratory trials using SPF and seropositive chickens. Field trials on commercial broilers and layers confirmed the satisfactory safety and efficacy profile of the vaccine. These data demonstrate the safety and efficacy of the novel vaccine candidate but also illustrate by an example the regulatory pathway and complexity of the contemporary vaccine development process in the regulated environment.