Just like the parent HEK293T cells, HEK293T/17 (ACE2+, TMPRSS2+, IFNAR1 KO) cells not only constitutively express the SV40 large T antigen (LTag) which is required for SV40 DNA replication, but also have the additional modifications i.e.: (1) IFNAR1 knock out (which is helpful in supporting viral infection and preventing the host cell apoptosis), (2) ACE2 knocked in (being a receptor of SARS-CoV-2, presence of ACE2 is very helpful in continued viral infection after transfection), and (3) TMPRSS2 knocked in (is the serine protease that cleaves the viral spike during infection. This evidence concerns the gene TMPRSS2 and infection.