MX1 and infection: This advance was inspired by elegant forward genetic studies in plants and mice, from 1986 onward, leading to the identification of Mx as a key influenza susceptibility locus in mice (SI Appendix, Fig. S1), and of Nramp1 as a key mycobacterial susceptibility locus in mice (SI Appendix, Fig. S1), as well as the discovery of the first loci conferring susceptibility to infection in plants (SI Appendix, Fig. S1).