Construction and next-generation sequencing analysis of a large phage-displayed V(NAR) single-domain antibody library from six naïve nurse sharks

Feng, Mingqian; Bian, Hejiao; Wu, Xiaolin; Fu, Tianyun; Fu, Ying; Hong, Jessica; Fleming, Bryan D; Flajnik, Martin F; Ho, Mitchell

Classical immunoglobin G (IgG) is widely used in many biotechnologies and therapeutics [1] . IgG is best described as a heterodimeric homodimer, consisting of two copies of disulfide-bonded heavy (H) and light (L) chains. The H and L chain variable (V) domains (VH and VL, respectively) combine to form the antigen-binding region. When these two V domains are synthesized as a dual-domain singlechain V fragment (scFv), the minimum size of the fragment is 25-30 kDa. In recent years, single-domain immunoglobulins such as the shark V NAR (new antigen receptor variable domain) and the camelid heavy-chain variable domain (V H H) antibodies have been explored, both of which can be isolated as soluble, stable, monomeric binding domains [2] [3] [4] . These V NAR and V H H domain antibodies range from 12 to 15 kDa in size, roughly half the size of a scFv binding domain.