Previously we reported that administration of WT mice with M-CSF or IL-4, or their infection with a recombinant HSV-1 expressing IL-4 (HSV-IL-4), pushes macrophages toward an M2 response, whereas injection of mice with IFN-γ or their infection with an IFN-γ expressing recombinant virus (HSV-IFN-γ) enhances an M1 response [57,58]. The gene discussed is IL4; the disease is infection.