Characteristics of a live avian influenza virus

Two avian influenza viruses were employed; a virulent wild-type (WT) parent and the cold variant (CV) which was an attenuated virus derived by genetic recombination at 25 C. The attenuated virus grows in embryonated eggs and chicken tracheal organ cultures. Infectious virus could be recovered from lung and turbinate. Infection with attenuated virus provided protection against infection with wild virus.