The Th1 immune response, in which cytokines like IFN-γ, TNF-α, and IL-2 play important roles, is necessary for plague prevention (Nakajima and Brubaker, 1993; Atreya et al., 2000; Brubaker, 2003; Elvin and Williamson, 2004; Nakayama et al., 2017). The gene discussed is IL2; the disease is plague.