Susceptibility was based not only on the expression of physiologically relevant receptors ACE2 and TMPRSS215, but also on the selection of a clone that has revealed – by substantial dose-dependent CPE accumulating after 8 h post infection (Supplementary Video 1) and after 3 d in culture – sensitivities in viral detection/isolation approaching that of diagnostic PCR (Supplementary Figs. 1 and 2). The gene discussed is ACE2; the disease is infection.