IFNG and infection: In contrast, the IFN-γ responses against the PPD-Bs in the transgenic cattle were significantly lower than those of the control group after infection (nine weeks: transgenic 0.40 ± 0.13 versus control 1.29 ± 0.12, P = 0.000; 12 weeks: transgenic 0.36 ± 0.14 versus control 1.45 ± 0.09, P = 0.000).