Submitted to: Avian Diseases
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/11/2008
Publication Date: 3/1/2009
Citation: Kapczynski, D.R., Gonder, E., Liljebjelke, K.A., Lippert, R., Petkov, D., Tilley, B. 2009. Vaccine induced protection from egg production losses in commercial turkey breeder hens following experimental challenge with a triple reassortant H3N2 avian influenza virus. Avian Diseases. 53:7-15. Interpretive Summary: Avian influenza (AI) is one of the most important viral diseases of poultry worldwide. Vaccination against AI virus in turkeys is widely practiced in the U.S. to control egg production losses associated with disease. The objectives of the present study were to extend the knowledge of vaccine induced protection by current AI vaccines in turkeys and determine if commercial vaccines protect against production losses from current AI field isolates. The results indicate that turkeys are better protected from production losses when the vaccine isolate is closely matched to the challenge isolate.
Technical Abstract: Avian influenza (AI) infection in turkey breeder hens can cause decreases in both egg production and quality which results in significant production losses. Recently, an H3N2 subtype of avian influenza triple reassortant containing human, swine, and avian gene segments was isolated from turkey breeder hens in North Carolina in 2003 (A/Turkey/North Carolina/03). Prior to this isolation, this viral subtype has been detected in both turkeys and swine in Ohio and Minnesota in 2004 and 2005, respectively, and is believed responsible for significant turkey significant production losses. The objective of this research was to determine if commercial oil emulsion inactivated AI H3 subtype vaccines would protect laying turkey hens from egg production losses following challenge with the 2003 H3N2 field virus isolate from North Carolina. Laying turkey hens were field vaccinated with two injections of either a monovalent (H3N4) or bivalent (H3N2, H1N1), commercial or autogenous vaccine, respectively, at 26 and 30 weeks of age, and challenged under BSL 3-Ag conditions at 32 weeks of age. Vaccine-induced protection was determined as protection from a 50% decrease in egg production within 21 days of challenge, and protection from a decrease in egg quality. Results indicate that following a natural route of challenge (eye drop / intranasal), both groups of vaccinated birds were protected from drops in egg production observed in sham-vaccinated hens. The results also indicate that the group of birds receiving H3 vaccine had decreased number of unsettable eggs, increased HI titers following challenge, and decreased virus isolations from cloacal swabs, compared to the sham-vaccinated birds. Lectin binding assays demonstrated that turkey ovaries contain both sialic acid alpha 2,3-galactose (SA alpha2,3gal) linked receptors and sialic acid alpha 2,6 gal (SA alpha2,6gal) linked receptors. The presence of the SA alpha2,6gal linked receptors may explain the circulation of influenza isolates containing mammalian HA gene segments in turkeys since they are the preferred receptor-specificity of mammalian influenza viruses. Overall these studies provide the first detailed protection studies of turkeys against an H3N2 triple reassortant AIV and demonstrated that SA alpha2,6 linked residues in turkey ovaries.