Viral loads at 7, 14, 18, 22, and 26 dpi in the oral and cloacal swabs of chickens infected with the recombinant rH120, rIBYZ, and rH120-S1/YZ strains. All data are presented as the mean ± standard error of the mean (SEM); ***Indicates an extremely significant difference at P ≤ 0.001; **Indicates a highly significant difference at 0.001 < P ≤ 0.01; *Indicates significant difference at 0.01 < P ≤ 0.05.