The resistance to reinfection of tracheal organ cultures from chickens previously infected with avian infections bronchitis virus.

Lower titres of avian infectious bronchitis (AIB) virus were found following the infection of tracheal organ cultures prepared from chickens that had been given AIB virus intranasally six weeks previously than were found following the infection of organ cultures prepared from untreated or from passively-immune chickens. No infectious virus was found in the tracheal organ cultures at the time they were prepared.