Abstract
The evolving epidemiology of avian influenza in Europe has led several countries to consider the implementation of vaccination against HPAI H5N1 viruses. In Northern Italy, the turkey production has been frequently associated with outbreaks of HPAI and lateral spread of the disease. We carried out vaccination trials in fattening turkeys to identify immunization schemes that might offer life-long protection with a low logistical burden on operations at the industry level. In this study, vaccination of day-old chicks with a recombinant HVT-vectored vaccine was applied to all birds. In one group, turkeys were boosted with a subunit vaccine, while a second group received a traditional inactivated whole virion vaccine as booster. The third group received no booster. Boosts were applied at 36 days of age. The animals were housed in BSL3 facilities and challenged. Assessment of the antibody response before and after the challenge was conducted by the HI assay and an indirect H5 ELISA. Clinical and virological protection were evaluated on a daily basis after the challenge. All vaccination regimens were found to be effective in protecting 100% of animals from mortality at 50 and 100 days of age, irrespective of the presence of medium-to-low antibody titers in all groups. Boosters improved virological protection at 50 days of age, while birds vaccinated with HVT alone achieved a superior virological protection at 100 days of age. This study has demonstrated that protection in heavy turkeys can be achieved with a hatchery vaccination hence reducing to a minimum the handling of turkeys.
Co-Author(s)
Lucrezia Vianello (EURL AI/ND), Sami Ramzi (EURL AI/ND), Elisa Mazzacan (EURL AI/ND), Silvia Maniero (EURL AI/ND), Daniele Facco (EURL AI/ND), Calogero Terregino (EURL AI/ND), Francesco Bonfante (EURL AI/ND)
Abstract Category
Diagnostics, vaccination, or other mitigation strategies for poultry and wildlife