Discovery and Characterization of a Novel CD4-Binding Adnectin with Potent Anti-HIV Activity

Antimicrob Agents Chemother. 2017 Jul 25;61(8):e00508-17. doi: 10.1128/AAC.00508-17. Print 2017 Aug.

Abstract

A novel fibronectin-based protein (Adnectin) HIV-1 inhibitor was generated using in vitro selection. This inhibitor binds to human CD4 with a high affinity (3.9 nM) and inhibits viral entry at a step after CD4 engagement and preceding membrane fusion. The progenitor sequence of this novel inhibitor was selected from a library of trillions of Adnectin variants using mRNA display and then further optimized for improved antiviral and physical properties. The final optimized inhibitor exhibited full potency against a panel of 124 envelope (gp160) proteins spanning 11 subtypes, indicating broad-spectrum activity. Resistance profiling studies showed that this inhibitor required 30 passages (151 days) in culture to acquire sufficient resistance to result in viral titer breakthrough. Resistance mapped to the loss of multiple potential N-linked glycosylation sites in gp120, suggesting that inhibition is due to steric hindrance of CD4-binding-induced conformational changes.

Keywords: Adnectin; CD4; HIV inhibitor; N17; gp41; human immunodeficiency virus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-HIV Agents / metabolism*
  • CD4 Antigens / metabolism*
  • Cell Line
  • Cell Surface Display Techniques
  • Epitopes / metabolism
  • Fibronectins / metabolism*
  • Glycosylation
  • HEK293 Cells
  • HIV Envelope Protein gp120 / metabolism*
  • HIV Envelope Protein gp160 / antagonists & inhibitors*
  • HIV-1 / drug effects*
  • Humans
  • Protein Binding

Substances

  • Anti-HIV Agents
  • CD4 Antigens
  • Epitopes
  • Fibronectins
  • HIV Envelope Protein gp120
  • HIV Envelope Protein gp160
  • gp160 protein, Human immunodeficiency virus 1