Fig. 2.

Schematic diagram of camelid antibodies (a, b) and different Single-domain antibody fragment (VHH) constructions (c). a The common structure of conventional antibodies: The antigen-binding fragment (Fab) consisting of Variable Light (VL), Variable Heavy (VH), Constant Light (CL) and Constant Heavy 1 (CH1) domains. b The structure of homodimeric camelid antibody: The antigen-binding fragment lack the VL, CL and CH1 domains and named Single-domain antibody fragment (VHH). c Different VHH constructions (adapted from Smolarek et al. 2012)