Protecting poultry from avian influenza, Newcastle disease, infectious bronchitis, and Gumboro disease with a single dose of a multivalent vaccine

Poultry is one of the fastest-growing sectors that is playing a major role in the provision of food security, economic development and poverty reduction. The demand for poultry meat and eggs has been increasing exponentially in recent years with the current annual population of poultry reaching over 50,000 million. This estimates that poultry production continues to grow by 24% in the next decade. However, the biggest threat in the sustainability of poultry production is the hyper prevalence of a multitude of infectious pathogens, such as different subtypes (H5, H7 and H9) of avian influenza viruses (AIV), Newcastle disease virus (NDV) and infectious bronchitis virus (IBV) and infectious bursal disease virus (IBDV). An estimated production loss from these pathogens account for at least 20% in many regions around the globe. Primarily, the control against these diseases is achieved through vaccination. However, the effectiveness of most of the current vaccines is suboptimal, where they may only reduce the manifestation of clinical disease and mortality, but infected animals continue to shed viruses resulting in a continual chain of infections to susceptible naïve and vaccinated animals resulting in reduced weight gain in meat birds and reduced egg production and quality in layers and breeder flocks. For example, despite the hyper deployment of multiple repeated doses of each vaccine for each target disease, the manifestation of pathogens continues in the form of endemic prevalence and farmers continue to bear debilitating losses with sometimes up to 100% flock mortality or loss of egg production and zoonotic infection threats in the case of AIV.

Current vaccines carry several inherent drawbacks including (i) one vaccine per disease which require multiple vaccinations and multiple bird handling resulting in expensive vaccination programmes; (ii) vaccines are given to chickens during the first three weeks of age, during this time period, birds carry maternally derived antibodies (MDA) which interferes with the vaccine performance and the efficacy of vaccines is reduced significantly; (iii) vaccines are produced in the eggs that are not ideal and requires replacement with cell culture systems; (iv) vaccines are not compatible for easy differentiation of infected from vaccinated animals (DIVA), therefore, disease-free status cannot be reclaimed easily in endemic disease regions. Therefore, new innovative vaccines are needed that could overcome these challenges.

This proposal plans to address these challenges and to develop a multivalent vaccine formulation that offers protection to chickens from up to six major pathogens (AIV-H5, AIV-H7, AIV-H9, NDV, IBV, IBDV). This project will be built on our novel Target Antigen Delivery Vaccine (TADV) platform which selectively delivers vaccine antigens to chicken immune cells and potentiate antigen-specific immune response. Our studies have provided evidence that a single dose of our TADV vaccine containing modified haemagglutinin (HA) antigen fused to the antibody that specifically binds to chicken antigen-presenting cells (APCs) induced significantly faster, higher and more durable immune response in MDA positive chickens compared to the untargeted counterpart or the conventional killed virus vaccines. Here, we will use our TADV technology and develop a multivalent TADV formulation in which a single dose will contain up to six immunogenic antigens from different viruses including (AIV-H5, AIV-H7, AIV-H9, NDV, IBV, IBDV). This multivalent vaccine can be delivered to day-old chickens at the hatchery overcoming MDA inference and inducing highly protective immunity in vaccinated birds. Availability of such novel protective and cost-effective disease control tools and strategies should minimise the impact of infectious diseases on farm animals, and offer substantial indirect economic, public health, environmental and social benefits globally.