|Sa E Silva, Mariana - Former ARS Employee|
|Donis, Ruben - Centers For Disease Control And Prevention (CDCP) - United States|
|Wan, Ziu-feng - Mississippi State University|
Submitted to: World Veterinary Poultry Association
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2015
Publication Date: 9/7/2015
Citation: Swayne, D.E., Sa E Silva, M., Spackman, E., Donis, R., Wan, Z. 2015. Variation in protection by seven inactivated H5 vaccine strains against eight H5N1 high pathogenicity avian influenza viruses in chickens [abstract]. Abstracts of the 19th World Veterinary Poultry Association Congress. p. 117.
Technical Abstract: H5N1 high pathogenicity avian influenza virus (HPAIV) is an important pathogen for poultry. Vaccines have assisted in control for poultry, and for human pandemic preparedness. However the genetic diversity and rapid antigenic drifting of the field viruses have led to inadequate protection. This study evaluated seven World Health Organization (WHO)-recommended H5N1 vaccine seed strains (clades 1.1, 2.1.3, 2.2.1, 220.127.116.11, 18.104.22.168, 2.3.4, and 7.1) in chickens for protection against eight diverse challenge HPAIVs (1.1, 2.2.1, 22.214.171.124, 2.1.3, 126.96.36.199A, 188.8.131.52B, 2.3.4, and 7.1) that currently or recently circulated in countries where the H5N1 HPAIV is endemic. All sham vaccinated birds died after HPAIV challenge, with mean death times (MDT) of 2-3.5 days. All seven vaccine seed strains provided =>80% survival against clade 7.1 and 2.2.1 challenge HPAIVs, but none of the seeds provided a similar, acceptable level of protection against 2.3.4 and 184.108.40.206B challenge viruses. No single vaccine seed strain provided adequate protection against all eight challenge HPAIVs, but some had delayed MDT (5 to 11 days) suggesting partial protection by the vaccines despite an outcome of death. Most of the vaccine-seed/challenge-HPAIV combinations were able to significantly decrease virus shedding titers compared to sham vaccinated groups. The antibody levels against the vaccine strain or the challenge strains were not always associated with protection from death, and distinct antigenic differences by cartography were inadequate to predict survival or death. This study highlights the complexity of field virus diversity and importance of geographic vaccine strain selection to provide adequate protection and control of H5N1 HPAIV.