A vaccine prepared from a non-pathogenic H5N1 influenza virus strain from the influenza virus library conferred protective immunity to chickens against the challenge with antigenically drifted highly pathogenic avian influenza virus.

The article presents a study which examines the efficacy of non-pathogenic influenza virus strain Hokkaido/Vac-1/2004 (H5N1) against the challenge with antigenically drifted highly pathogenic avian influenza virus (HPAIV). The study has collected tracheal and cloacal swabs of dead or sacrificed chicken and determined virus infectivity titers using plaque assays. The result showed increased hemagglutination inhibition (HI) antibody titers of about 2⁴ fold in all vaccinated chickens.