Mucosal vaccination against highly pathogenic avian influenza (HPAI) is potentially superior to conventional parenteral vaccination because it is expected to induce mucosal antibody responses in the respiratory tract. We tested whether intraocular vaccination with an inactivated HPAI virus induced protective antibody responses in chickens. Chickens were inoculated intraocularly twice with 104 hemagglutination units of an inactivated H5N1 HPAI virus. Four weeks after the second vaccination, the chickens were challenged with a lethal dose of the homologous H5N1 HPAI virus. The results showed that most of the vaccinated chickens mounted positive antibody responses. The median serum hemagglutination inhibition titer was 1:80. The addition of CpG oligodeoxynucleotide or cholera toxin to the vaccine did not enhance serum antibody titers. Anti-hemagglutinin immunoglobulin G, but not immunoglobulin A, was detected in oropharyngeal secretions. In accordance with these antibody results, most of the vaccinated chickens survived lethal challenge with H5N1 HPAI virus and did not shed the challenge virus in respiratory or digestive tract secretions. Our results show that intraocular vaccination with an inactivated HPAI virus induces not only systemic but also mucosal antibody responses and confers protection against HPAI in chickens.
(Viral Disease and Epidemiology Research Division)
Hikono H. et al (2011) patent pending: intraocular vaccination to avian influenza; PCT/JP2012/63604