SARS-CoV-1 monoclonal Spike S1 VHH neutralizing antibody, a.a. 1-127(full length), with C-terminal Avi-Tag fused to the Fc portion of Human IgG1, expressed in a HEK293 cell expression system. MW = 43 kDa. This protein runs at a higher M.W. by SDS-PAGE due to glycosylation. This protein is enzymatically biotinylated using Avi-Tag™ technology. Biotinylation is confirmed to be ≥90%. VHHs are single-domain antibodies from camelids.