Open AccessVariation in protection of four divergent avian influenza virus vaccine seed strains against eight clade 2.2.1 and 2.2.1.1. E gyptian H 5 N 1 high pathogenicity variants in poultry
Author(s) -
Spackman Erica,
Swayne David E.,
PantinJackwood Mary J.,
Wan XiuFeng,
Torchetti Mia K.,
Hassan Mohammad,
Suarez David L.,
Sá e Silva Mariana
Publication year - 2014
Publication title -
influenza and other respiratory viruses
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.743
H-Index - 57
eISSN - 1750-2659
pISSN - 1750-2640
DOI - 10.1111/irv.12290
Subject(s) - biology , virology , vaccination , influenza a virus subtype h5n1 , subclade , hemagglutination assay , virus , clade , hemagglutinin (influenza) , antigenic variation , antigenic drift , microbiology and biotechnology , titer , phylogenetics , gene , genetics
Background Highly pathogenic ( HP ) H 5 N 1 avian influenza virus ( AIV ) was introduced to E gyptian poultry in 2006 and has since become enzootic. Vaccination has been utilized as a control tool combined with other control methods, but for a variety of reasons, the disease has not been eradicated. In 2007, an antigenically divergent hemagglutinin subclade, 2.2.1.1, emerged from the original clade 2.2.1 viruses. Objectives The objective was to evaluate four diverse AIV isolates for use as vaccines in chickens, including two commercial vaccines and two additional contemporary isolates, against challenge with numerous clade 2.2.1 and clade 2.2.1.1 H 5 N 1 HPAIV E gyptian isolates to assess the variation in protection among different vaccine and challenge virus combinations. Methods Vaccination‐challenge studies with four vaccines and up to eight challenge strains with each vaccine for a total of 25 vaccination‐challenge groups were conducted with chickens. An additional eight groups served as sham‐vaccinated controls. Mortality, mean death time, morbidity, virus, and pre‐challenge antibodies were evaluated as metrics of protection. Hemagglutination inhibition data were used to visualize the antigenic relatedness of the isolates. Results and conclusions Although all but one vaccine‐challenge virus combination significantly reduced shed and mortality as compared to sham vaccinates, there were differences in protection among the vaccines relative to one another based on challenge virus. This emphasizes the difficulty in vaccinating against diverse, evolving virus populations, and the importance of selecting optimal vaccine seed strains for successful HPAIV control.