Novel AI Diva Recombinant Vaccines for Duck
The NOVADUCK project brings together both private (two companies and one SME) and public sector stakeholders (European reference laboratories and agencies on avian influenza) from four European countries with the aim of developing and evaluating new highly protective and cost-effective avian influenza live vaccines for ducks, based on live viral vectors and in line with the DIVA strategy (Differentiating Infected from Vaccinated Animals).
Viral vectors will be engineered to optimise both their immunogenicity and protective capacities. Vaccine candidates will be pre-screened for safety and immunogenicity using newly developed duck-specific immunological tools. The best vaccine candidates will be evaluated for efficacy in an HPAI H5N1 challenge-model in ducks. A serological DIVA test, able to detect infection in vaccinated duck flocks, will be generated, and the effect of vaccination on genetic and antigenic drift of H5N1 will be assessed.[+] Read More
The ongoing outbreak of H5N1 HPAI has recently spread from Asia to Africa and Europe, posing a real public threat as HPAI can occasionally infect humans. Ducks play a major role in the epidemiology of avian influenza because wild waterfowl, including ducks, constitute the natural reservoir of all subtypes of influenza A virus. Experimental infection of ducks with recent isolates indicates a longer shedding period and a selection for lower virulence variants, suggesting that duck has become the 'Trojan horse' of Asian H5N1 AI.
Although biosecurity is the first line of defence against HPAI, strategic use of vaccination is clearly recognised as a tool to help eradicate HPAI in an infected country. Most studies evaluating the efficacy of AI vaccines have been performed in chickens, and duck studies have been relatively rare. Existing inactivated AI vaccines are less immunogenic in ducks than in chickens and must generally be administered twice to be fully efficient; furthermore, there is no commercially available DIVA test to monitor AI infection in birds injected with this type of vaccine. Therefore, highly efficient, cost-effective, DIVA-compatible AI vaccines for ducks are still greatly needed.
In this specific context, live vector-based vaccines hold the greatest promise and are one of the most effective options. Indeed, some live recombinant vector-based AI vaccines have shown excellent results in chickens, but they are not necessarily adapted for use in ducks. Expected advantages of this type of vaccine include administration at a younger age, mass administration, rapid onset of immunity, and compatibility with the DIVA strategy.
The NOVADUCK project is designed to demonstrate and exploit the potential of live vector vaccines to develop a new generation of highly efficient and cost-effective AI vaccines for ducks and therefore could contribute to eradicating AI from the ecosystem.
The NOVADUCK project aims to develop and evaluate new highly protective and cost-effective avian influenza live vaccines for ducks based on live vectors and in line with the DIVA strategy. More specifically, the NOVADUCK project will:
The NOVADUCK project is designed to identify the optimal AI immunogenic sequence to be inserted into a vector. New specific tools to evaluate humoral, cellular and mucosal immunity induced in ducks will be developed. Three types of vector-based vaccines containing the optimal immunogenic sequence will be generated, and their immunogenicity using different administration modes will be compared to that of existing inactivated AI vaccines using the newly developed immunological tools. A challenge model using the most recent and representative AI isolates in which clinical signs, oral and cloacal shedding can be significantly detected in all challenged birds will be set up in ducks and will be used to compare the efficacy induced by the newly selected vector-based vaccine candidates with that induced by existing vaccines. Studies will be designed to verify that the newly developed vaccines show clear advantages over existing vaccines. The compatibility of these vector-based vaccines with newly developed DIVA tests will also be verified. In addition, data will be generated on the effect of vaccination of ducks on genetic/antigenic drift of the challenge virus.
The newly developed vector-based AI vaccines for ducks generated during the NOVADUCK project could be available for vaccination of ducks in countries in which the biosecurity measures are not sufficient to control AI H5 infection. The selected vaccine candidates should show clear advantages over existing vaccines, such as DIVA-compatibility, low cost, early onset of immunity, adjuvant-free, and/or ease of administration (e.g. mass vaccination, duckling administration at the hatchery). These new types of vaccines would be suitable for emergency vaccination, thereby limiting the mass slaughtering of poultry around an infected area, or for preventive vaccination in high risk or enzootic area.
Some of the newly developed vaccine candidates may also be safe and efficacious in other species, including other poultry (e.g. chickens, turkeys and geese), but also mammals (e.g. cats, dogs, pigs, horses), making them ideal multi-species AI vaccine candidates. Additionally, if efficacy can be obtained after administration by the oral route, the potential exists to use such vaccines to vaccinate wild ducks and thus potentially contribute to the eradication of AI from the ecosystem.
The duck-specific immunological tools that will be developed during the NOVADUCK project would also be essential to evaluate the immunogenicity of any existing, as well as future, duck vaccines. In particular, the DIVA test could be used to monitor infection in vaccinated flocks.
The development of a reproducible AI challenge model in ducks will be useful to define the standard for evaluation of efficacy of duck AI vaccine. The protection data generated during the project would also help to define the minimal level of protection that should be expected for an acceptable AI duck vaccine. Overall, the project should give new tools to control AI infection in a species playing a significant role in AI epidemiology.