Growth kinetic studies of avian infectious bronchitis virus in tracheal organ cultures.

An egg-adapted vaccine strain (H120) and an organ culture-passaged field strain (HV-10) of avian infectious bronchitis (AIB) virus were propagated in tracheal organ cultures and their growth kinetics examined using nine-day-old embryonated fowl eggs and chick tracheal explants for virus assay. When the H120 strain was assayed in embryonated eggs, titres were approximately log10 2-0 ID50 (50 per cent infectious dose) per ml higher than when assays were performed in tracheal explants. The HV-10 strain, assayed in tracheal explants, yielded higher titres than did the H120 strain, but when assayed in embryonated eggs, yielded only minimal and variable virus titres.