virus shedding after h9n2 strain challenge of spf chickens immunized by an experimental nano-adjuvant and commercial oil emulsion avian influenza (h9n2) vaccines

abstract background and aims: vaccination of poultry has a major impact on the prevention and control of avian influenza viruses. nanobiotechnology techniques provide a new approach for improvement of influenza vaccine efficacy. in this study, efficacy of an inactivated nano-adjuvant vaccine developed based on an endemic h9n2 virus was evaluated in spf chickens. materials and methods: in each three trial 40 specific pathogen free (spf) white leghorn chickens were used in four groups. chickens from treatment groups (n= 10) via subcutaneous route received a single dose of the nano-adjuvant or the oil emulsion razi® h9n2 vaccines. chickens in the control group c received antigen only. all the birds were challenged with h9n2 strain on day 21 post-vaccination. cloacal and tracheal swabs were taken at 1-10 days post-challenge and viral shedding was examined using inoculation of spf embryonated eggs. results: both vaccinated spf chicken groups induced complete protection against clinical signs. viral shedding in the nano-adjuvant h9n2 vaccinated chickens was completely blocked after challenge with a homologous h9n2 virus. statistical analysis based on the protection effects of the chickens immunized with nano-adjuvant and the razi® h9n2 vaccine showed no significant difference, but there was a significant difference to un-vaccinated group. conclusions: the results of this study indicated that the nano-adjuvant vaccine was efficacious in protection of spf chickens over h9n2 infection. further field experiments are needed to demonstrate the efficacy of the vaccines under field conditions.