Efficacy of a novel in ovo-attenuated live vaccine and recombinant vaccine against a very virulent infectious bursal disease virus in chickens

• Published in: Journal of Veterinary Medical Science Vol. 83; no. 11; pp. 1686 - 1693
• Main Authors: OKURA, Takashi, OTOMO, Hiroki, SUZUKI, Shoko, ONO, Yuji, TANENO, Akira, OISHI, Eiji
• Format: Journal Article
• Language: English
• Published: Tokyo JAPANESE SOCIETY OF VETERINARY SCIENCE 2021; Japan Science and Technology Agency; The Japanese Society of Veterinary Science
• Subjects: Antibodies; Atrophy; attenuated live infectious bursal disease virus vaccine; Bursa of Fabricius; in ovo inoculation; Infections; infectious bursal disease virus; infectious bursal disease virus viral protein 2 expression; Poultry; recombinant turkey herpesvirus; Vaccine efficacy; Vaccines; Virology; Virulence; Viruses; VP2 protein
• ISSN: 0916-7250; 1347-7439; 1347-7439
• DOI: 10.1292/jvms.21-0319

Infectious bursal disease (IBD) causes severe economic damage to the poultry industry worldwide. To prevent IBD virus (IBDV) infection, live virus vaccines have been widely used in chickens having wide-ranging levels of maternally derived antibodies. But, the risks of infection with other pathogens because of lesions related to atrophy of the bursa of Fabricius in vaccinated chickens are a concern. To resolve the problems, a recombinant turkey herpesvirus (HVT) vaccine expressing IBDV-VP2 protein (rHVT-IBD) has been developed. However, the induction of neutralizing antibodies by rHVT-IBD against a virulent IBDV might be delayed compared with that by the live IBD vaccine, leading to the high risks of IBDV infection for young chickens. To find the best selection of IBDV vaccine for the onset of immunity, we examine the protective efficacy of a novel in ovo-attenuated live IBDV (IBD-CA) vaccine and the rHVT-IBD vaccine in young chickens challenged with a very virulent IBDV (vvIBDV) strain. We show that the protective efficacy of IBD-CA vaccine was higher than that of the rHVT-IBD vaccine in 14-day-old chickens challenged with the vvIBDV strain, leading to the risk of IBDV infection for young chickens when vaccinated with rHVT-IBD. Our results suggest that farmers should select the best vaccines to maximize vaccine efficacy in consideration of the vaccine characteristics, prevalence levels of IBDV in the areas, and initial MDA levels of the chickens since the attenuated live and recombinant vaccines play a role in the different vaccine efficacies.