Notwithstanding the role of type I interferons, the strong antiviral effect of IFN-γ was demonstrated early on for HCMV in vivo, and a polymorphism in the IFN-γ gene was correlated with susceptibility to HCMV infection in kidney transplant recipients [24, 39, 40]. The gene discussed is IFNG; the disease is cytomegalovirus infection.