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Title: Vaccine protection of chickens against antigenically diverse H5 highly pathogenic avian influenza isolates with a live HVT vector vaccine expressing the influenza hemagglutinin gene derived from a clade 2.2 avian influenza vi

Author
item Kapczynski, Darrell
item ESAKI, MOTOYUKI - Biomune Company
item DORSEY, KRISTI - Biomune Company
item JIANG, HAI JUN - US Department Of Agriculture (USDA)
item JACKWOOD, MARK - University Of Georgia
item MORAES, MAURO - Biomune Company
item GARDIN, YANNICK - Biomune Company

Submitted to: Vaccine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2014
Publication Date: 1/20/2015
Publication URL: https://handle.nal.usda.gov/10113/61291
Citation: Kapczynski, D.R., Esaki, M., Dorsey, K., Jiang, H., Jackwood, M., Moraes, M., Gardin, Y. 2015. Vaccine protection of chickens against antigenically diverse H5 highly pathogenic avian influenza isolates with a live HVT vector vaccine expressing the influenza hemagglutinin gene derived from a clade 2.2 avian influenza vi. Vaccine. 33(9):1197-1205. doi: 10.1016/j.vaccine.2014.12.028.

Interpretive Summary: Avian influenza (AI) viruses cause significant morbidity and mortality in wild and domestic bird populations and threaten the U.S. poultry food supply. Highly Pathogenic (HP) AI is an economically important disease of poultry that can impact global trade. New outbreaks of HPAI in commercial poultry represent one of the most critical diseases to contain and require reporting to the World Organization for Animal Health. We tested a new commercial vaccine for protection of poultry against a number of different HPAI viruses. In these studies we demonstrate that the new AI vaccine provided good protection of poultry against lethal challenge. These studies further our knowledge of protection of poultry against new and ongoing HPAI outbreaks.

Technical Abstract: Vaccination is an important tool in the protection of poultry against avian influenza (AI). For field use, the overwhelming majority of AI vaccines produced are inactivated whole virus formulated into an oil emulsion. However, recombinant vectored vaccines are gaining use for their ability to induce protection against heterologous isolates and ability to overcome maternal antibody interference. Protective immunity against highly pathogenic AI (HPAI) depends largely on the development of antibody against epitopes of the hemagglutinin (HA) glycoprotein. In these studies, we compared protection of chickens provided by a recombinant turkey herpesvirus (rHVT) vaccine expressing the HA gene from a clade 2.2 H5N1 strain (A/swan/Hungary/4999/2006) against homologous H5N1 as well as heterologous H5N1 and H5N2 HPAI challenge. In the first set of experiments, groups of birds were subcutaneously vaccinated at day of age and challenged four weeks later with a homologous H5N1 isolate, A/whooper swan/Mongolia/L245/2005. The results demonstrated all vaccinated birds were protected from clinical signs of disease and mortality following challenge. In addition, oral and cloacal swabs taken from challenged birds demonstrated that vaccinated birds had lower incidence and titers of viral shedding compared to sham-vaccinated birds. To examine protection against genetically distant HPAI, birds were challenged with either a H5N1 of Indonesian origin (A/chicken/West Java Subang/29/2007) or a H5N2 HPAI Mexican isolate (A/chicken/Queretero/14588-19/1994). In those studies, 80-95% of birds receiving the rHVT-AI vaccine at day of age survived challenge with fewer birds shedding virus after challenge than sham vaccinated birds. Interestingly, antibodies from protected chickens vaccinated with the rHVT-AI did not demonstrate high levels of cross reaction against heterologous H5 AI virus in hemagglutination inhibition assays prior to challenge. In contrast, in vitro cytotoxicity analysis demonstrated that splenic T lymphocytes from rHVT-AI vaccinated chickens recognized MHC-matched target cells infected with H5, H6, H7, and H9 AI virus. Taken together, these studies provide support for the use of rHVT vaccines expressing HA to protect poultry against multiple lineages of HPAI, and that both humoral and cellular immunity induced by live vaccines likely contributes to protection.