C57BL/6J mice immunosuppressed with anti-IFNAR1 mAb MAR1-5A3 and infected (intraperitoneally [IP] or subcutaneously [SC]) with CCHFV strain IbAr10200 develop severe disease with substantial weight loss (>20% from baseline measured on day 0) resulting in lethality 4 to 8 days post infection (dpi) (3% survival at 14 dpi, n = 5/149) (Figure 1A) [19]. The gene discussed is IFNAR1; the disease is infection.