FIG. 3.
Virulence in chickens. Survival and disease after oculonasal inoculation with PBS (mock), DkUkr63-Wt, DkUkr63-It98HACS, DkUkr63-Hk220HACS, or DkUkr63-R28HACS. The birds were observed for 10 days for clinical signs and classified as healthy (0), slightly ill (0.5), or ill (1); the daily clinical index (DCI) was calculated from the sum of individual clinical scores from all birds divided by the number of animals per group (10 chickens). Chickens 3 and 9 from the group infected with DkUkr63-It98HACS developed central nervous symptoms.