Submitted to: Developments in Biologicals
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 16, 2007
Publication Date: December 1, 2007
Citation: Swayne, D.E., Suarez, D.L. 2007. Current developments in avian influenza vaccines including food safety aspects in vaccinated birds. Developments in Biologicals. 30:121-131.
Interpretive Summary: Killed avian influenza (AI) vaccines have been used over the past 30 years to prevent disease in some poultry. Recently, biotechnology methods have led to development of improved AI vaccines that use virus vectors to produce AI proteins and include fowl poxvirus, Newcastle disease virus, and other viruses. These new vectored vaccines can be used to shorten the manufacturing process, match the vaccine more closely to circulating AI viruses, and allow administration without handling the birds. The use of vaccines in poultry of HPAI affected countries will protect poultry, and will provide additional safety to the grower and consumer by greatly reduced growth and excretion of AI virus from respiratory and digestive tracts of poultry.
Oil emulsified inactivated low or high pathogenicity (HP) avian influenza AI viruses were the only type of vaccines available for many years. More recently, recombinant fowl poxvirus and avian paramyxovirus type 1 vaccines with AI H5 gene inserts (+ or - N1 gene insert) have been licensed for use. Other emerging technologies may overcome existing limitations of poultry vaccination and result in vaccines that can be grown in tissue culture systems for more rapid vaccine production; provide optimized protection as the result of closer genetic relationship to field viruses; can be mass applied by aerosol, drinking water, or in ovo administration; and provide easier strategies for identifying infected birds within vaccinated populations; i.e. DIVA. These technologies are likely to include attenuated AI viruses, viral-vectored vaccines like Newcastle disease virus, Mark’s disease virus and adenoviruses, and sub-unit vaccines. These new technologies should be licensed only after demonstration of purity, safety, efficacy and potency against AI viruses, and for live vectored vaccines a restriction on lateral transmission of vaccines to unvaccinated birds. Usage of vaccines in HPAI infected countries not only will provide protection to poultry, but will provide additional safety to the grower and consumer. Experimental studies have shown that AI immunized birds following HPAI virus challenge lack virus in meat and minimal amounts in eggs, and greatly reduced replication and shedding from respiratory and alimentary tracts.