To evaluate the specificity with which our bioengineered cotton bound SARS-CoV-2 virus, we repeated the above in vitro infection experiment using a different human coronavirus NL63 strain, HCoV-NL63, which only shares 17% similarity with the SARS-CoV-2 RBD36 despite also binding to the ACE2 cell receptor. This evidence concerns the gene ACE2 and infection.