Figure 1.

Beau-R displays an attenuated phenotype in vivo. SPF chickens were inoculated at 7 days of age with 10⁴ PFU of infectious bronchitis virus (IBV) strain Beau-R, M41-CK or PBS for mock infection. The birds were assessed from 2 to 7 dpi for the presence of clinical signs. (a) The average number of snicks per bird was calculated and (b) the percentage of birds exhibiting rales. Only birds infected with M41-CK displayed clinical signs. (c) Ciliary activity was measured in trachea harvested from six randomly selected birds (n = 6) at 4 and 6 dpi. The average percentage for each group is displayed with error bars representing standard error of the mean (SEM). Statistical differences were assessed using a two-way ANOVA followed by Tukey analysis for multiple comparisons and are represented by **** (p < 0.0001).