We found that ∆IMD mutant flies were somewhat susceptible to the four viruses DCV, FHV, DXV, and IIV6, but not SINV, agreeing with previous studies showing a reduction in lifespan of 1–2 days for Rel mutant flies after viral infection (Costa et al., 2009; Goto et al., 2018; Sansone et al., 2015). The gene discussed is REL; the disease is viral infectious disease.