- Academic Editor
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Background: Outbreaks of highly pathogenic avian influenza viruses
cause huge economic losses to the poultry industry worldwide. Vaccines that can
protect chickens from infections caused by various variants of highly pathogenic
H5Nx avian influenza viruses are needed owing to the continuous emergence of new
variants. We previously showed that vaccines containing the H5 cleavage-site
peptide from clade 2.3.4.4. H5N6 avian influenza virus protects chickens from
infection with homologous clade 2.3.4.4. H5N6 avian influenza virus, but not from
infection with the heterologous clade 1 H5N1 avian influenza virus. Therefore, we
developed bivalent peptide vaccines containing H5 cleavage sites of viruses from
both clades to protect chickens from both H5N1 and H5N6 avian influenza viruses.
Methods: Chickens were vaccinated with two doses of a combined peptide
vaccine containing cleavage-site peptides from clade 1 and clade 2.3.4.4. highly
pathogenic H5N1 and H5N6 avian influenza viruses and then challenged with both
viruses. The infected chickens were monitored for survival and their tracheae and
cloacae were sampled to check for viral shedding based on the median tissue
culture infectious dose of 50 (log