TOOLS AND RESOURCES NaLi-H1: A universal synthetic library of humanized nanobodies providing highly functional antibodies and intrabodies Sandrine Moutel1,2,3†, Nicolas Bery4,5†, Virginie Bernard1, Laura Keller4,5,6, Emilie Lemesre1,2, Ario de Marco1, Laetitia Ligat7, Jean-Christophe Rain8, Gilles Favre4,5,6, Aure´ lien Olichon4,5*, Franck Perez1,2* 1Institut Curie, PSL Research University, Paris, France; 2CNRS UMR144, Paris, France; 3Translational Research Department, Institut Curie, Paris, France; 4Inserm, UMR 1037-CRCT, Toulouse, France; 5Faculte´ des Sciences Pharmaceutiques, Universite´ Toulouse III-Paul Sabatier, Toulouse, France; 6Institut Claudius Regaud, Toulouse, France; 7Le Poˆle Technologique du Centre de Recherches en Cance´rologie de Toulouse, plateau de prote´omique, Toulouse, France; 8Hybrigenics Service, Paris, France Abstract In vitro selection of antibodies allows to obtain highly functional binders, rapidly and at lower cost. Here, we describe the first fully synthetic phage display library of humanized llama single domain antibody (NaLi-H1: Nanobody Library Humanized 1). Based on a humanized synthetic single domain antibody (hs2dAb) scaffold optimized for intracellular stability, the highly diverse library provides high affinity binders without animal immunization. NaLi-H1 was screened following several selection schemes against various targets (Fluorescent proteins, actin, tubulin, p53, HP1). Conformation antibodies against active RHO GTPase were also obtained. Selected hs2dAb were *For correspondence: aurelien. used in various immunoassays and were often found to be functional intrabodies, enabling tracking
[email protected] (AO); Franck. or inhibition of endogenous targets. Functionalization of intrabodies allowed specific protein
[email protected] (FP) knockdown in living cells. Finally, direct selection against the surface of tumor cells produced hs2dAb directed against tumor-specific antigens further highlighting the potential use of this †These authors contributed library for therapeutic applications.