Protection afforded by avian influenza vaccination programs consisting of a novel RNA particle and an inactivated avian influenza vaccine against a highly pathogenic avian influenza virus challenge in layer chickens

Authors: LADMAN, BRIAN - University Of Delaware; GELB, JACK - University Of Delaware; SAUBLE, LAUREN - University Of Delaware; MURPHY, MARCY - University Of Delaware; Spackman, Erica

Submitted to: Avian Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2019
Publication Date: 5/20/2019
Citation: Ladman, B., Gelb, J., Sauble, L., Murphy, M., Spackman, E. 2019. Protection afforded by avian influenza vaccination programs consisting of a novel RNA particle and an inactivated avian influenza vaccine against a highly pathogenic avian influenza virus challenge in layer chickens. Avian Pathology. 48(4):371-381. https://doi.org/10.1080/03079457.2019.1605148.
DOI: https://doi.org/10.1080/03079457.2019.1605148

Interpretive Summary: Vaccines can be used to help prevent death and disease from bird flu, however little data is available on vaccination programs in long-lived chickens, such as table egg layers. Here several vaccination programs which involved different types of vaccines and booster shots that were administered at different times were compared. The two vaccine types tested included a conventional killed vaccine and a novel commercial "RNA particle" (RP) vaccine. First, it was shown that the novel RP vaccine provided very good protection, the best protection was seen in groups that received at least one shot with the RP vaccine. Second, this provides data on how long immunity lasts after the chickens are given their shots. In this case the longest time between a vaccination and exposure to live virus was 11 weeks, and the chickens were still protected (as long as they received a shot of the RP vaccine at some time). This provide information which can be used for developing programs to successfully vaccinate table egg laying chickens against bird flu.

Technical Abstract: The efficacies of an oil adjuvanted-inactivated reverse genetics derived H5 avian influenza virus (AIV) vaccine and an alphavirus replicon RNA particle (RP) AIV vaccine were evaluated in commercial leghorn chickens. The challenge utilized A/Turkey/MN/12582/2015, an isolate representing the U.S. H5N2 Clade 2.3.4.4 responsible for the 2015 highly pathogenic avian influenza (HPAI) epornitic in commercial poultry in the United States. As part of a long term, 36 week study, chickens were challenged at seven weeks of age after receiving a single vaccination, at 18 weeks of age after following a vaccine prime-single boost program and at 36 weeks of age after a prime-double-boost vaccine program. Pre-challenge serum antibody titers were not a consistent indicator of protection as titers were generally greater in birds receiving the adjuvanted-inactivated reverse genetics vaccine whole H5 AI vaccine yet survivability was greater in RP vaccinated chickens. All vaccine programs reduced virus orophyngeal and cloacal shedding and mortality compared to the non-vaccinated control birds. However, chickens receiving at least one administration of the RP vaccine generally had diminished viral shed especially from the cloacal swabbings. A detectable serum antibody response and protection was observed through 18 weeks post vaccination. Our data suggest that in conjunction with a comprehensive eradication, enhanced biosecurity and controlled marketing plan, vaccination programs of commercial layer chickens with novel RP vaccines may represent an important tool for preventing HPAI related mortalities and decreasing viral load during a catastrophic influenza outbreak.