Rapid isolation of IgNAR variable single-domain antibody fragments from a shark synthetic library

Cuiying Shao, Christopher John Secombes, Andrew Justin Radcliffe Porter

Research output: Contribution to journalArticlepeer-review

53 Citations (Scopus)


The immunoglobulin isotype IgNAR (Novel Antigen Receptor) was discovered in the serum of the nurse shark (Ginglymostoma cirratum) and wobbegong shark (Orectolobus maculates) as a homodimer of two protein chains, each composed of a single variable domain (V) domain and five constant domains. The IgNAR variable domain contains an intact antigen-binding site and functions as an independent domain able to react to antigen with both high specificity and affinity. Here we describe the successful construction of a synthetic phage-displayed library based upon a single anti-lysozyme clone HEL-5A7 scaffold, which was previously selected from an immune IgNAR variable domain library. The complementarity-determining region 3 (CDR3) loop of this clone was varied in both length and composition and the derived library was used to pan against two model proteins, lysozyme and leptin. A single anti-lysozyme clone (Ly-X20) and anti-leptin clone (Lep-12E1) were selected for further study. Both clones were shown to be functionally expressed in Escherichia coli, extremely thermostable and bind to corresponding antigens specifically. The results here demonstrate that a synthetic IgNAR variable domain library based on a single framework scaffold can be used as a route to generate antigen binders quickly, easily and without the need of immunization.

Original languageEnglish
Pages (from-to)656-665
Number of pages10
JournalMolecular Immunology
Issue number4
Early online date24 Feb 2006
Publication statusPublished - Jan 2007


  • novel antigen receptor
  • shark
  • synthetic phage-displayed library
  • CDR3
  • heavy-chain antibodies
  • receptor gene nar
  • antigen receptor
  • phage display
  • light-chains
  • nurse shark
  • somatic hypermutation
  • structural-analysis
  • escherichia-coli
  • selection


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