10.3389/fimmu.2018.03037.s002 Starlynn C. Clarke Starlynn C. Clarke Biao Ma Biao Ma Nathan D. Trinklein Nathan D. Trinklein Ute Schellenberger Ute Schellenberger Michael J. Osborn Michael J. Osborn Laure-Hélène Ouisse Laure-Hélène Ouisse Andrew Boudreau Andrew Boudreau Laura M. Davison Laura M. Davison Katherine E. Harris Katherine E. Harris Harshad S. Ugamraj Harshad S. Ugamraj Aarti Balasubramani Aarti Balasubramani Kevin H. Dang Kevin H. Dang Brett Jorgensen Brett Jorgensen Heather Anne N. Ogana Heather Anne N. Ogana Duy T. Pham Duy T. Pham Payal P. Pratap Payal P. Pratap Preethi Sankaran Preethi Sankaran Ignacio Anegon Ignacio Anegon Wim C. van Schooten Wim C. van Schooten Marianne Brüggemann Marianne Brüggemann Roland Buelow Roland Buelow Shelley Force Aldred Shelley Force Aldred Image_1_Multispecific Antibody Development Platform Based on Human Heavy Chain Antibodies.pdf Frontiers 2019 heavy chain antibodies VH domains domain antibodies antibody discovery platform next-generation sequencing repertoire sequencing transgenic rats B cell development 2019-01-07 04:15:01 Figure https://frontiersin.figshare.com/articles/figure/Image_1_Multispecific_Antibody_Development_Platform_Based_on_Human_Heavy_Chain_Antibodies_pdf/7552370 <p>Heavy chain-only antibodies (HCAbs) do not associate with light chains and their V<sub>H</sub> regions are functional as single domains, forming the smallest active antibody fragment. These V<sub>H</sub> regions are ideal building blocks for a variety of antibody-based biologics because they tolerate fusion to other molecules and may also be attached in series to construct multispecific antibodies without the need for protein engineering to ensure proper heavy and light chain pairing. Production of human HCAbs has been impeded by the fact that natural human V<sub>H</sub> regions require light chain association and display poor biophysical characteristics when expressed in the absence of light chains. Here, we present an innovative platform for the rapid development of diverse sets of human HCAbs that have been selected in vivo. Our unique approach combines antibody repertoire analysis with immunization of transgenic rats, called UniRats, that produce chimeric HCAbs with fully human V<sub>H</sub> domains in response to an antigen challenge. UniRats express HCAbs from large transgenic loci representing the entire productive human heavy chain V(D)J repertoire, mount robust immune responses to a wide array of antigens, exhibit diverse V gene usage and generate large panels of stable, high affinity, antigen-specific molecules.</p>