IL4 and infection: Evidence of Th2 cytokine skewing also occurs during bRSV infection, as cells and lymph fluid from bRSV infected calves showed enhanced IL-4 and IL-13 production in the serum and tissues as early as day 4 post-infection, as well as increased IgE levels, eosinophilia, and lower IFNγ at 6 days post-infection [26,115,116,117,118].