Cross-clade protection against H5N1 HPAI strains recently isolated from commercial poultry in Egypt with a single dose of a baculovirus based vaccine

The current avian influenza epidemic in Egypt caused by circulation of genetically and antigenically diverse H5N1 HPAI viruses in poultry is controlled by applying vaccination among other measures. In this context, the use of a DIVA (differentiating infected from vaccinated animals) vaccination strategy utilizing a vaccine capable of inducing protection against multiple antigenic variants may result as an additional control tool to the existing ones. In this study the efficacy of a single-shot recombinant baculovirus-based vaccine in specific-pathogen-free chickens was tested by experimental challenge with genetically and antigenically diverse H5N1 HPAI viruses belonging to clades 2.2.1 and 2.2.1.1, which have been circulating in Egypt since 2010. A single dose of vaccine, administration at 10 days of age, was shown to confer 100% clinical protection, with a decrease or suppression of virus shedding.