Combating avian influenza through systematic analysis of antigenic drift, genetic variation, and development of novel diagnostic tools and vaccines

The global poultry industry has shown great promise for increased, cost-effective production of animal protein to meet food security challenges. Poultry production has contributed significantly to economic growth in transitioning the economies of developing nations; it has helped meet goals in poverty alleviation and reduction in rural unemployment, particularly amongst women. However, the emergence and spread of the highly pathogenic avian influenza (HPAI) H5N1, and the widespread endemic presence of low pathogenicity avian influenza (LPAI) subtypes in many countries has threatened the sustainability of the sector through incurring heavy losses in both commercial and backyard poultry production. The rapid genetic evolution and potential reassortment of HPAI and LPAI subtypes in birds remains a credible threat for pandemic emergence. Control of these viruses presents formidable challenges to public health and veterinary infrastructures. Intervention programs require accurate and timely detection of virus subtypes, and typically involve ring culling of at-risk flocks, movement and trade restrictions, and vaccination campaigns. In poor countries, large scale culling has become impractical for economic, ecological and ethical reasons, since the viruses are endemic over wide regions and in multiple diverse avian species. The effectiveness and suitability of currently available diagnostic tools and vaccines is limited by insufficient laboratory capacity, the inherent diversity of wild type circulating viruses, and inadequate vaccine delivery mechanisms.

The proposed research will exploit next generation biotechnological approaches to gain new knowledge and improve control strategies to minimize economic losses due to influenza within the poultry sector, and to mitigate the risk of pandemic emergence. We will examine the different epidemiology and ecology of influenza in Vietnam and Pakistan, in relationship to differing levels of industrialization of their poultry sectors, and to provide insight into the different pathways that impact on sustainable control of AIV. These studies will advance our understanding of how genetic and antigenic diversity influences the protective efficacy of vaccines and the sensitivity/specificity of diagnostic technologies. The precise determination of antigenic epitopes critical for induction of protective immunity in chickens and ducks will inform the design of more broadly effective vaccines. These broadly cross-reactive and protective AIV antigens will be integrated into proven viral vaccine vectors; we will engineer duck enteritis virus (DEV) and the herpesvirus of turkeys (HTV) to produce multivalent recombinant live vaccines capable of protecting ducks or chickens against AIV, as well as duck plague and Marek's disease, respectively. These next generation vaccines be delivered through mass vaccination strategies (in ovo) and will allow easy differentiation of infected from vaccinated birds (DIVA). We will develop novel rapid diagnostics to differentiate major AIV subtypes infecting poultry at the pen-side. These technologies have the potential to transform control strategies by empowering farmers to identify infected flocks at an early stage, and the dual protection against highly prevalent economically important diseases (duck plague and Marek's disease) will motivate uptake of the vaccine. Through our community-based study sites, we will explore farmer attitudes and perceptions regarding disease interventions, and assess the impact of novel technologies. The knowledge and improved tailored-made tools for control and management of AIV in Vietnam and Pakistan will reduce production losses and help prevent outbreaks with a high risk of zoonotic infections. In addition to direct benefits to farming communities, the improved control measures may offer substantial indirect economic, public health, environmental and social benefits to wider communities on both the national and global scale.

The poultry industry in developing countries has made dramatic progress in improving production of animal protein at affordable prices to rapidly expanding populations. However, sustainability of poultry production is threatened by widespread morbidity and mortality due to avian influenza viruses. These viruses cause devastating economic losses and pose risks for zoonotic infections, particularly among poor farmers who work under conditions of low biosecurity. Viral spread can be reduced through mass slaughter and vaccination. However, large scale depopulation of flocks is impractical in developing countries due to its economic and social costs. The effectiveness of both diagnostics and vaccines have been compromised due to rapid evolution of these viruses, and in many regions, multiple divergent strains co-circulate, thereby requiring broadly cross-reactive vaccines and vigilant surveillance to inform vaccine strain matching. Similarly, diagnostics may lose their effectiveness as the viruses evolve.

The present proposal aims to bring together expertise in the UK, Vietnam and Pakistan to develop novel vaccines and diagnostics that are tailor-made to protect against AIVs currently circulating in Vietnam and Pakistan. This will be achieved through a multifaceted approach to select optimal, broadly cross-protective antigens, develop recombinant multivalent vaccines that protect against both AIV as well as other endemic production diseases (duck plague and Marek's disease), and complementary rapid pen-side diagnostics. Detailed assessments to evaluate how the novel vaccines and diagnostics benefit stakeholder populations will be conducted at different levels of the value chain. Field trials, case studies, community-based activities, and modeling efforts will improve our understanding of the socio-economic impacts of both AIV, and the optimal use of different control strategies to protect farmer livelihoods, public health, and food security.

Endemic prevalence of H5N1 and H9N2 in south and southeast Asia continues to threaten the sustainability of poultry production systems and the livelihoods in rural communities of developing and transitional economies such as Vietnam and Pakistan. Although new and improved technologies are most certainly required for better disease control in poultry, the development and deployment of technical solutions will require a multidisciplinary approach, and in-depth understanding of the socio-economic and behavioural factors that drive AIV disease emergence. Many AIV subtypes are 'silent' or of low pathogenicity in poultry yet have the potential to cause significant public health risks. Therefore the control of AIV can result in conflict between stakeholder communities, where risk mitigation must be balanced with preserving economic livelihoods. Our proposed research will provide integrated and innovative approaches to prevention and control of AIV, by advancing both basic and applied science, and building upon the following components: 1) direct linkages to national government infrastructures for poultry disease surveillance, to obtain timely access to contemporary data on virus circulation; 2) high calibre and cutting edge research on construction of chimeric multivalent vaccines, recombinant proteins, and novel Lateral Flow Device diagnostics; 3) establish strong links with in-country commercial partners to enhance vaccine manufacturing capacity, thereby addressing knowledge gaps and human resource needs in the private sector; and 4) engaging in participatory research activities with stakeholders (farmers, traders, market workers) in rural communities to better understand risk perception and behavioural drivers of technology uptake. Thus, the strategic objectives of this partnership are aligned with the long-term goals of many stakeholders with an interest in animal health, public health and food security such as Department for International Development (DFID), World Organisation for Animal Health (OIE), Food and Agriculture Organization of the United Nations (FAO), World Health Organisation (WHO), partner institutions, and their national government agencies (BBSRC, MRC, DEFRA).
The research will harness expertise in the UK and Vietnam to improve the control of AIV for sustainable growth of the poultry industry and reduction of zoonotic infection risks. Due to the global nature of the poultry industry and free movement of poultry meat and egg products, improvement of AIV control in Vietnam and Pakistan will also have a major impact on reducing the threats from these viruses to the UK. The outcomes of this research will be communicated to stakeholders via multiple mechanisms. Adoption of the DFID Research Open and Enhanced Access Policy20 will ensure use of public databases and information sharing. Data and reagents will be shared promptly via peer-reviewed open access journals, through multilingual websites and presentations at conferences and workshops. Public engagement aspects of the project will be facilitated through community forums with farmers groups, and through local TV and radio coverage in Vietnam and Pakistan.
The PIs have experience collaborating with potential beneficiaries outside the immediate academic community, including governmental and non-governmental organizations and the corporate sector. Knowledge exchange and commercialisation activities will be managed through Business Development Officers who will lead on any detailed identification of and discussions with potential business partners. Socio-economic issues involved in uptake of veterinary vaccines and diagnostics will be evaluated by community-based participatory research activities in farming communities. We are committed to performing high calibre research and to training the next generation of scientists for multi-disciplinary research that addresses priority concerns of global health, infectious disease epidemiology, vaccinology and diagnostics.