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Protection of commercial turkeys following inactivated or recombinant H5 vaccine application against the 2015U.S. H5N2 clade 126.96.36.199 highly pathogenic avian influenza virus
- Kapczynski, Darrell R., Sylte, Matthew J., Killian, Mary L., Torchetti, Mia K., Chrzastek, Klaudia, Suarez, David L.
- Veterinary immunology and immunopathology 2017 v.191 pp. 74-79
- Alphavirus, Influenza A virus, Meleagrid herpesvirus 1, RNA, antibodies, avian influenza, blood serum, cloaca, control methods, disease outbreaks, epizootic diseases, genes, hemagglutination, hemagglutinins, poults, recombinant vaccines, survival rate, turkeys, vaccination, viral shedding, viruses, North America
- 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 188.8.131.52 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 as a possible future control strategy. The aim of these studies were to evaluate the efficacy three H5 vaccines to aid in control of HPAI in commercial turkeys. Three different vaccine technologies were evaluated for efficacy: 1) inactivated reverse genetic laboratory-generated virus encoding a clade 184.108.40.206 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 220.127.116.11 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 18.104.22.168 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 recombinant vaccines for use in turkeys as a control measure for clade 22.214.171.124 H5 HPAI epizootics.