Here, productive infection by B.1 and VOC Alpha was completely abolished by the ACE2 knock-out in a multicycle assay, reflected by absence of both secreted genomic RNA (S8F Fig) and infectivity (Fig 7E), and reconstitution of knock-out cells with ACE2 expression in trans, as opposed to an empty vector, rescued infection (S8G Fig). The gene discussed is ACE2; the disease is infection.