Protection of White Leghorn chickens by U.S. emergency H5 vaccines against clade 2.3.4.4 H5N2 high pathogenicity avian influenza virus

Authors: BERTRAN, KATERI - Consultant; Balzli, Charles; LEE, DONG-HUN - Orise Fellow; Suarez, David; Kapczynski, Darrell; Swayne, David

Submitted to: Vaccine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/4/2017
Publication Date: 5/26/2017
Publication URL: https://handle.nal.usda.gov/10113/5691062
Citation: Bertran, K., Balzli, C.L., Lee, D., Suarez, D.L., Kapczynski, D.R., Swayne, D.E. 2017. Protection of White Leghorn chickens by U.S. emergency H5 vaccines against clade 2.3.4.4 H5N2 high pathogenicity avian influenza virus. Vaccine. 35:6336-6344. http://dx.doi.org/10.1016/j.vaccine.2017.05.051.
DOI: https://doi.org/10.1016/j.vaccine.2017.05.051

Interpretive Summary: During December 2014-June 2015, the U.S. experienced the worst high pathogenicity avian influenza (HPAI) outbreak event for the poultry industry. Three vaccines, developed based on updating existing registered vaccines or currently licensed technologies, were evaluated for possible use. We assessed the efficacy of a reverse genetics avian influenza inactivated vaccine (rgH5N1), a recombinant herpesvirus turkey vectored vaccine (rHVT-H5), and an RNA particle vaccine (RP-H5) in White Leghorn chickens against clade 2.3.4.4 H5N2 HPAI virus challenge. In Study 1, single (rHVT-H5) and prime-boost (rHVT-H5 + rgH5N1 or rHVT-H5 + RP-H5) vaccination strategies protected 3-week-old chickens with high levels of protective immunity and significantly reduced virus shedding. In Study 2, single vaccination with either rgH5N1 or RP-H5 vaccines provided clinical protection in adult chickens and significantly reduced virus shedding. In Study 3, double rgH5N1 vaccination protected adult chickens from clinical signs and mortality when challenged 20 weeks post-boost, with high levels of long-lasting protective immunity and significantly reduced virus shedding. These studies support the use of genetically related vaccines for emergency vaccination programs against clade 2.3.4.4 H5Nx HPAI virus in young and adult layers.

Technical Abstract: During December 2014-June 2015, the U.S. experienced a high pathogenicity avian influenza (HPAI) outbreak caused by clade 2.3.4.4 H5Nx Goose/Guangdong lineage viruses which was the worst HPAI event for the poultry industry. Three vaccines, developed based on updating existing registered vaccines or currently licensed technologies, were evaluated for possible use: an inactivated reverse genetics H5N1 vaccine (rgH5N1) and an RNA particle vaccine (RP-H5), both containing the hemagglutinin gene of clade 2.3.4.4 strain, and a recombinant herpesvirus turkey vectored vaccine (rHVT-H5) containing the hemagglutinin gene of clade 2.2 strain. The efficacy of the three vaccines, alone or in combination, was assessed in White Leghorn chickens against clade 2.3.4.4 H5N2 HPAI virus challenge. In Study 1, single (rHVT-H5) and prime-boost (rHVT-H5 + rgH5N1 or rHVT-H5 + RP-H5) vaccination strategies protected 3-week-old chickens with high levels of protective immunity and significantly reduced virus shedding. In Study 2, single vaccination with either rgH5N1 or RP-H5 vaccines provided clinical protection in adult chickens and significantly reduced virus shedding. In Study 3, double rgH5N1 vaccination protected adult chickens from clinical signs and mortality when challenged 20 weeks post-boost, with high levels of long-lasting protective immunity and significantly reduced virus shedding. These studies support the use of genetically related vaccines for emergency vaccination programs against clade 2.3.4.4 H5Nx HPAI virus in young and adult layer chickens.