Effect of H7N1 vaccination on highly pathogenic avian influenza H7N7 virus transmission in turkeys

This study describes the results of a transmission experiment with highly pathogenic avian influenza (HPAI) H7N7 virus in 12-week-old turkeys. Cloacal and tracheal swabs as well as serum samples were taken to monitor the infection both in inoculated and in susceptible contact turkeys, which were all either unvaccinated, vaccinated once or vaccinated twice with H7N1. Swabs were tested by real-time RT-PCR and serum samples with hemagglutination inhibition test (HI). Unvaccinated contact birds had a mean infectious period of 6.2 days, and an estimated transmission rate parameter of 1.26 per infectious bird per day. However, no virus shedding was found in inoculated vaccinated turkeys and thus we concluded that vaccination with H7N1 protected against challenge with HPAI H7N7 virus.