Figure 1.

Construction and characterization of dimeric and trimeric nanobodies (Nbs) targeting the Middle East respiratory syndrome (MERS) coronavirus (MERS-CoV). (A) Heavy chain-only antibody (HcAb) consists of two constant heavy domains (CH2 and CH3) and heavy chain variable domains (VHHs). Monomeric Nb (Mono-Nb) was constructed previously by linking a MERS-CoV receptor-binding domain (RBD)-specific VHH and a C-terminal His₆, and dimeric Nb (Di-Nb) and trimeric Nb (Tri-Nb) were constructed by linking two or three Mono-Nbs with GGGGS linkers and a C-terminal His₆ tag for easy purification. (B) SDS-PAGE (left) and Western blot (right) analysis of MERS-CoV RBD-specific Nbs. The molecular weight marker (in kDa) is shown on the left. MERS-CoV RBD-targeting Mono-Nb was included as comparison, and MERS-CoV RBD-specific mAb (MERS mAb) and SARS-CoV RBD-specific mAb (SARS mAb) were used as controls. Anti-llama antibody was used for Western blot analysis.