Combating highly pathogenic avian influenza: Novel vaccination strategies using recombinant live avian viral vaccine vectors

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Combating highly pathogenic avian influenza: Novel vaccination strategies using recombinant live avian viral vaccine vectors. Avian influenza (AI) viruses (or the 'avian flu' as it is commonly called) naturally exist in wild birds such as waterfowl and shore birds where the virus is highly diverse and generally not pathogenic. These low pathogenic avian influenza (LPAI) viruses routinely cross over from the wild-bird reservoir and infect domestic poultry, frequently becoming highly pathogenic viruses (HPAI), which are extremely dangerous to commercial poultry and are occasionally fatal to humans. In the recent outbreaks of HPAI viruses of H5 and H7 subtypes in many parts of the world, including the EU, more than 200 million domestic poultry have either died or been culled, impecting huge socio-economic costs. The current epidemic of HPAI H5N1 originating from south East Asia and recently transmitted over long distances via migratory birds is unprecedented. The magnitude of risk that migratory birds are posing to the United Kingdom and other EU countries is not clear, however, there is growing evidence (recent death of migratory swan by H5N1 in Fife, Scotland) suggesting that the prevention and control of AI disease outbreak in poultry and other captive birds will be a major challenge for many years to come. To date the main strategy for controlling HPAI in domestic poultry in UK and in some other countries has been eradication of the virus by large scale culling of infected and contact flocks. However, the current world-wide epidemic has severely affected the economies of developed as well as developing countries. Therefore, for ethical, ecological and economic reasons, it is no longer considered acceptable to control and eradicate AI mainly by the mass killing of animals. As a result the European Parliament, the World Organization for Animal Health (OIE) and Food and Agriculture Organization (FAO) have allowed not only emergency vaccination, following disease outbreak, but also preventive vaccination as an additional tools for the control of AI. Currently, the available AI inactivated vaccines are produced in embryonated eggs and have several disadvantages. We propose to develop novel vaccines using some of the state of the art biotechnological tools. These will allow the administration of live viral vaccines as single injection either at hatch or into eggs before they hatch (in ovo vaccination). These new improved vaccines will be safe, effective and economical, and above all protect the commercial poultry and other domestic birds from disease and dissemination of AI viruses into the environment, consequently preventing AI virus spread, averting the looming global pandemic threat.