The Pan-VHH ELISA kit is designed for the detection and quantification of VHHs displayed on the surface of lentiviral vectors (LVVs) or lipid nanoparticles (LNPs). This assay is broadly compatible with VHHs derived from different species including alpaca- and llama-derived VHHs, as well as humanized VHHs. It can be used with VHHs targeting a wide range of antigens, including but not limited to CD3, CD5, CD7, CD8, and CD47.