However, LCMV by itself induces profound CD8+ T cell proliferation and activation, even in wild-type animals and immune defenses against this virus have been shown to rely on IFN-γ produced by CD8+ T cells as well as perforin-mediated CD8+ T cell cytotoxicity, independently of HLH occurrence (Kägi et al., 1994; Badovinac et al., 2003). The gene discussed is PRF1; the disease is hemophagocytic syndrome.