|Chrzastek, Klaudia - Orise Fellow|
Submitted to: International Symposium on Avian Influenza
Publication Type: Abstract Only
Publication Acceptance Date: 2/1/2015
Publication Date: 4/12/2015
Citation: Kapczynski, D.R., Zsak, A., Greene, C.R., Chrzastek, K. 2015. Comparison of potency required for protection against H7N3 or H5N1 highly pathogenic avian influenza following vaccination and challenge with homologous virus [abstract]. 9th International Symposium on Avian Influenza, Athens, Georgia. p. 71.
Technical Abstract: Outbreaks of H5 and H7 highly pathogenic avian influenza (HPAI) in commercial poultry are a constant threat to food supplies and animal/human health. While vaccination can enhance protection and reduce the spread of disease, there is considerable evidence that the level of immunity required for protection varies by subtype and virulence of field virus. To address this relationship between challenge isolate and vaccine potency, we evaluated the antigenic loaded required for protection against recent HPAI viruses of differing subtypes. In these studies, individual vaccines were prepared from inactivated A/chicken/Jalisco/CPA1/2012 H7N3 or A/chicken/Vietnam/2011 H5N1 HPAI containing different hemagglutinin titers with 512, 128, or 64 units per dose. Birds received a single vaccination of a single dose and were challenged with matching subtype at three weeks post vaccination with 10^6 EID50 per bird. The results demonstrate that following H5N1 HPAI challenge, only 50% protection was observed in birds receiving 512 HA units per dose. In contrast, birds receiving the lowest dose (64 HA units) of H7N3 vaccine were completely protected from mortality. Interestingly, the mean death time in control birds was higher with the H5N1 challenge virus as opposed to the H7N3 virus, implicating virulence of the challenge virus as a factor in protection. The immunological characterizations following vaccination and challenge with both subtypes will be discussed along with impact on virus shedding.