PROS1 and viral infectious disease: More importantly, S2-4D, S2-5D, S2-8D, S2-4A and the antisera obtained by immunization of mice with sfGFP-S(1127-1167) (Fig. 4), which carries the defined 13-residue epitope, can inhibit the S protein-mediated membrane fusion and SARS-CoV-2 infection, indicating that these antibodies neutralized virus infection through blocking the key step of virus–host cell membrane fusion.