Vaccination for fowl plague

Influenza A/turkey/Oregon/71 virus has antigenic characteristics of fowl plague virus but is avirulent for chickens. The virus was inoculated intratracheally in chickens at several dosage levels and resulted in the formation of antibody and immunity against fowl plague. The avirulent virus replicated in chickens and was recoverable by tracheal swab specimens up to 4 days after inoculation. Although the virus was transmitted to contact controls at the time when their cagemates were inoculated, it was not transmitted to contact controls placed with chickens inoculated 24 hours earlier. After 10 passages in chickens, the virus remained avirulent for chickens and turkeys.