Protection of commercial turkeys following inactivated or recombinant H5 vaccine application against the 2015 U.S. H5N2 clade 2.3.4.4 highly pathogenic avian influenza virus

Authors: Kapczynski, Darrell; SYLTE, MATTHEW - Animal And Plant Health Inspection Service (APHIS); KILLIAN, MARY - Animal And Plant Health Inspection Service (APHIS); TORCHETTI, MIA - Animal And Plant Health Inspection Service (APHIS); CHRZASTEK, KLAUDIA - Orise Fellow; Suarez, David

Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2017
Publication Date: 8/7/2017
Publication URL: https://handle.nal.usda.gov/10113/5815315
Citation: Kapczynski, D.R., Sylte, M.J., Killian, M.L., Torchetti, M.K., Chrzastek, K., Suarez, D.L. 2017. Protection of commercial turkeys following inactivated or recombinant H5 vaccine application against the 2015 U.S. H5N2 clade 2.3.4.4 highly pathogenic avian influenza virus. Veterinary Immunology and Immunopathology. 191(2017):74-79. http://dx.doi.org/10.1016/j.vetimm.2017.08.001.
DOI: https://doi.org/10.1016/j.vetimm.2017.08.001

Interpretive Summary: Highly pathogenic avian influenza (HPAI) virus remains to be a major threat to the U.S. poultry industry. Between December 2014 and June 2015, the U.S. experienced the largest recorded foreign HPAI animal disease outbreak with over 47 million birds dead or euthanized from exposure to a H5 HPAI virus. Layer chickens and turkeys were most affected by this outbreak. The estimated economic impact of this outbreak produced loses up to $3.3 billion USD, and resulted in 18 trade partners banning import of U.S. poultry. During the outbreak, the ability of vaccines to protect commercial turkeys was unknown. In this study, we found that the use of three different types of H5 avian influenza vaccines protected commercial turkeys against disease from the HPAI virus. The vaccines also reduced shedding of the virus demonstrating the potential to block transmission of the virus to other birds. Results of these vaccine trials led to USDA conditional approval for use of two vaccines in turkeys. These valuable tools can be used to protect commercial turkey flocks from future HPAI outbreaks

Technical Abstract: Between December 2014 and June 2015, North America experienced the largest recorded foreign animal disease outbreak with over 47 million poultry dead or euthanized from viral exposure to a clade 2.3.4.4 H5 highly pathogenic avian influenza (HPAI) epizootic. Soon after the epizootic began, the U.S. Department of Agriculture (USDA) began testing the efficacy of different vaccines in poultry as a possible future control strategy. The goal of these experiments was to evaluate the efficacy of three H5 vaccines to aid in control of HPAI in commercial turkeys. Three vaccine technologies were evaluated for efficacy: 1) inactivated reverse genetic derived virus encoding a clade 2.3.4.4 H5 hemagglutinin (HA) gene (rgH5), 2) recombinant turkey herpesvirus encoding a clade 2.2. H5 HA (rHVT-AI), and 3) recombinant replication-deficient alphavirus RNA particle vaccine encoding a clade 2.3.4.4 H5 HA (RP-H5). All vaccines tested significantly (P<0.01) increased survival rates between vaccinated and sham vaccinated groups of poults challenged with A/turkey/Minnesota/12582/2015 clade 2.3.4.4 H5N2 HPAI. The rgH5 vaccine had detectable serum hemagglutination inhibition (HI) antibody against the challenge virus, and significantly reduced the frequency and level of viral shedding from oropharyngeal and cloacal swabs at days 2 and 4 post-challenge. Vaccination with only rHVT-AI or RP-H5 was not 100% protective, and failed to significantly reduce viral shedding post-challenge. A combined prime and boost strategy with the rHVT-AI and RP-H5, or rHVT-AI and rgH5, was 100% protective against lethal H5N2 HPAI challenge. Results of these studies led to USDA conditional approval of commercially available rgH5 and RP-H5 vaccines for use in turkeys as a control measure for clade 2.3.4.4 H5 HPAI epizootics.