Instead, we found that the fitness advantage of IFNAR1-disrupted cells during SARS-COV-2 infection was mediated by an increase in cell proliferation between days 4 and 8 post-infection (Fig 4A, 4C), a finding that was mirrored by the antiproliferative response of uninfected cells to exogenous β-IFN treatment (Fig 6G). This evidence concerns the gene IFNAR1 and infection.