The Shark Strikes Twice: Hypervariable Loop 2 of Shark IgNAR Antibody Variable Domains and Its Potential to Function as an Autonomous Paratope

Mar Biotechnol (NY). 2015 Aug;17(4):386-92. doi: 10.1007/s10126-015-9642-z. Epub 2015 May 24.

Abstract

In this present study, we engineered hypervariable loop 2 (HV2) of the IgNAR variable domain in a way that it solely facilitates antigen binding, potentially functioning as an autonomous paratope. For this, the surface-exposed loop corresponding to HV2 was diversified and antigen-specific variable domain of IgNAR antibody (vNAR) molecules were isolated by library screening using yeast surface display (YSD) as platform technology. An epithelial cell adhesion molecule (EpCAM)-specific vNAR was used as starting material, and nine residues in HV2 were randomized. Target-specific clones comprising a new HV2-mediated paratope were isolated against cluster of differentiation 3ε (CD3ε) and human Fcγ while retaining high affinity for EpCAM. Essentially, we demonstrate that a new paratope comprising moderate affinities against a given target molecule can be engineered into the vNAR scaffold that acts independent of the original antigen-binding site, composed of complementarity-determining region 3 (CDR3) and CDR1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Binding Sites / genetics
  • Binding Sites, Antibody / genetics
  • Flow Cytometry
  • Gene Library
  • Humans
  • Immunoglobulin Heavy Chains / chemistry
  • Immunoglobulin Heavy Chains / genetics*
  • Models, Molecular*
  • Protein Structure, Tertiary
  • Sharks / genetics*
  • Sharks / immunology*

Substances

  • Immunoglobulin Heavy Chains