ACE2 and severe acute respiratory syndrome: Moreover, 80R IgG1 inhibits syncytial formation between cells expressing S protein and cells expressing ACE2.13 In a further study, 80R IgG1 could efficiently protect mice from SARS-CoV infection, noting that the core of its target is aa 324 to 503 in the S protein of SARS-CoV.14 This is also the first effective antibody against SARS-CoV screened from an antibody library.