IFN-γ is the major Th1 cytokine and is considered to be a correlate of immunity to infection with Bp (Santanirand et al., 1999; Ketheesan et al., 2002; Tippayawat et al., 2009; Silva and Dow, 2013; Jenjaroen et al., 2015; Dunachie et al., 2017; Burtnick et al., 2018; Sengyee et al., 2021). The gene discussed is IFNG; the disease is infection.