Vaccine protection of chickens against antigenically diverse H5 highly pathogenic avian influenza isolates with a live HVT vector vaccine expressing the influenza hemagglutinin gene derived from a clade 2.2 avian influenza virus.

•A recombinant HVT vaccine expressing a H5 HA gene provided homologous and heterologous protection.•Antibodies exhibited high levels of reaction against homologous but not heterologous H5 virus.•Lymphocytes from vaccinated chickens recognized target cells infected with H5, H6, H7, or H9 AI.•Live recombinant vaccines induce humoral and cellular immunity which contribute to protection.