Among the effectors that promote bacterial reduction, early secretion of interferon-gamma (INF-γ) by NK cells, DC, and Th1 cells greatly enhance macrophage-mediated killing of B. pertussis; mice lacking INF-γ developed a lethal infection after challenge with B. pertussis (Mahon and Mills, 1999; Higgins et al., 2006). This evidence concerns the gene IFNG and infection.