It has been reported that in cattle experimentally infected with M. bovis the expression of IFN-γ, TNF-α, iNOS and IL-4 by PBMCs increase in response to infection, andthat animals with high pathology express more IFN-γ, TNF-α, iNOS and IL-4 than animals with low pathology [33]. The gene discussed is TNF; the disease is infection.