IFNG and infection: Furthermore, MAP infections depend on several factors including the infectious dose, the long incubation period of MAP, which is longer than 2 years in vivo, the protective Th1 cell response, and IFN-γ release followed by the activation of antimicrobial mechanisms; however, 10–15% of infected cattle will develop clinical signs of PTB [22], which results in MAP carriers not being detectable at the subclinical stage of the disease.