3.3.2  Antibody response
Antibodies against the IBVs were measured using an ELISA (Fig. 7C). None of the birds in the rH120 or rH120-S1/YZ groups showed a positive antibody response at 7 dpv, whereas 100% of the birds had an antibody response detectable at 14 dpv, with the antibody level gradually increasing during the observation period. However, there was no significant difference in the level of serum antibodies between rH120-vaccinated chickens and rH120-S1/YZ-vaccinated chickens. No positive serum antibody response was detected in the non-vaccinated controls.