Protection of chickens vaccinated with different schemes including the 4/91 IBV vaccine strain against field IBV strain Italy 02: preliminary results

The ability of different vaccine programmes (including the 4/91 vaccine strain) to protect against field infectious bronchitis virus (IBV) strain Italy 02 was investigated using specific pathogen free (SPF) chickens. Protection, as measured by assessing ciliary activity of the tracheal epithelium following challenge, was excellent with all vaccine schedule used in this trial. The data provided by this study also indicates that vaccination programmes induced adequate protection against both challenges at 36 and at 56 days of age.