Effect of incubation temperature on infectivity titration of mouse brain-passaged avian infectious bronchitis virus in laboratory host systems.

Mouse brain-passaged infectious bronchitis virus (IBV) could not be assayed for its infectivity at 39.5 degrees C, but could be so at 37 degrees C and 39.5 degrees C. Antigen accumulation was not detected by immunofluorescence in CEK cells infected with mouse brain-passaged IBV at 39.5 degrees C, perhaps due to the difference in the cellular environments.