Selection and Characterization of Specific Nanobody Against Human Immunoglobulin G

Nanobodies (or VHHs) are the smallest antigen-binding domain of heavy chain antibodies, which naturally occur in camelidae. The small size, monomeric nature, low immunogenicity, high solubility and stability, as well as high affinity to target in nanomolar range, makes nanobodies a promising tool for diagnostic and therapeutic application. In the present study, we developed and identified the nanobody against human IgG from an immune library using phage display technique. For this goal, we performed four rounds of selection procedures on immobilized human IgG through biopanning. A clone named R1Nb was selected and expressed as His-tagged protein, and purified by nickel affinity chromatography. In addition, R1Nb was further characterized for binding specificity and affinity. Results demonstrated that R1Nb was highly specific for human IgG and its constant affinity was about 7.5 nM. Taken together, our achieved results indicate the potential of R1Nb as a promising tool in research and may be used for therapeutic purposes as a fusion part of target-specific nanobody.