Generation of camelid VHH bispecific constructs via in-cell intein-mediated protein trans-splicing.

: Production of various combinations of bispecific variable domain of heavy chain of heavy chain-only antibody (VHH) constructs to evaluate their therapeutic potential usually requires several gene-engineering steps. Here, we present an alternative method of creating bispecific VHH constructs in vivo through protein trans-splicing (PTS) reaction; this method may reduce the number of gene manipulation steps required. As a proof-of-concept, we constructed a bispecific antibody (bsAb) containing an anti-epidermal growth factor receptor VHH and anti-green fluorescent protein VHH, and we evaluated and confirmed its bispecificity. We also tested antibody labeling by fluorescent protein tagging using the PTS reaction. Compared with the conventional gene construction method, bsAb construction via PTS is a promising alternative approach for generating multiple bsAb combinations.