title: Laboratory methods for assessing and licensing influenza vaccines for poultry.
abstract: Avian influenza vaccines for poultry are based on hemagglutinin proteins, and protection is specific to the vaccine subtype. Over 113 billion doses have been used between 2002 and 2010 for high pathogenicity avian influenza control. No universal vaccines are currently available. The majority of avian influenza vaccines are inactivated whole influenza viruses that are grown in embryonating eggs, inactivated, emulsified in oil adjuvant systems, and injected into chickens. Live virus-vectored vaccines such as recombinant viruses of fowl pox, Newcastle disease, herpesvirus of turkeys and duck enteritis containing inserts of avian influenza virus hemagglutinin genes have been used on a more limited basis. In studies to evaluate vaccine efficacy and potency, the protocol design and its implementation should address the biosafety level needed for the work, provide information required for approval by Institutional Biosafety and Animal Care Committees, contain information on seed strain selection, provide needed information on animal subjects and their relevant parameters, and address the selection and use of challenge viruses. Various metrics have been used to directly measure vaccine induced protection. These include prevention of death, clinical signs, and lesions; prevention of decreases in egg production and alterations in egg quality; quantification of the reduction in virus replication and shedding from the respiratory tract and gastrointestinal tracts; and prevention of contact transmission in in vivo poultry experiments. In addition, indirect measures of vaccine potency and protection can be developed and validated against the direct measures and include serological assays in vaccinated poultry and assessment of the content of hemagglutinin antigen in the vaccine. These indirect assessments of protection are useful in determining if vaccine batches have a consistent ability to protect. For adequate potency, vaccines should contain 50 mean protective doses of antigen, which corresponds to 0.3-7.8 μg of hemagglutinin protein, depending on immunogenicity of individual seed strains.
authors.affiliation: Exotic and Emerging Avian Viral Diseases Unit, Southeast Poultry Research Laboratory¸ US Department of Agriculture, ARS, 934 College Station Rd., Athens, GA, 30605, USA, david.swayne@ars.usda.gov.
authors.forename: David E
authors.initials: DE
authors.lastname: Swayne
mesh_terms: D035661:Animal Care Committees; D000818:Animals; D009980:Influenza A virus / Q000276:immunology; D007252:Influenza Vaccines / Q000009:adverse effects / Q000276:immunology*; D007753:Laboratories; D008004:Licensure; D011200:Poultry / Q000276:immunology*; D012449:Safety
chemical_list: D007252:Influenza Vaccines