Polyvalent Nanobody Structure Designed for Boosting SARS-CoV-2 Inhibition

Area of Science:

• Biotechnology
• Nanotechnology
• Virology

Background:

• Coronavirus (SARS-CoV-2) mutations present ongoing challenges for pandemic control and antiviral drug development.
• Developing effective antiviral therapies for viral neutralization remains a critical need.

Purpose of the Study:

• To create a novel polyvalent nanobody (Nb) structure for enhanced inhibition of SARS-CoV-2 infections.
• To investigate a new DNA-protein conjugation strategy for developing potent virus inhibitors.

Main Methods:

• Conjugation of single-stranded DNA (ssDNA) with receptor-binding domain (RBD)-targeting Nbs.
• Assembly of ssDNA-Nb conjugates around gold nanoparticles (AuNPs) via DNA hybridization to form polyvalent nanobody structures (PNS).
• Characterization of PNS binding affinity using surface plasmon resonance (SPR) and evaluation of viral entry inhibition against SARS-CoV-2 strains and variants.

Main Results:

• The developed PNS demonstrated a ~1000-fold improvement in binding affinity to SARS-CoV-2 trimeric spike proteins compared to monomeric Nbs.
• PNS exhibited over a 400-fold enhancement in viral inhibition against SARS-CoV-2 WA/2020, BQ1.1, and XBB variants compared to free Nbs.
• The strategy allows for controlled Nb density on the nanoparticle, facilitating spatial pattern-matching with spike protein binding sites.

Conclusions:

• The novel PNS strategy offers a facile and robust approach for developing effective antiviral agents.
• This DNA-protein conjugation chemistry provides a versatile platform for creating nanobody-based inhibitors against emerging viral threats.
• The enhanced binding affinity and viral inhibition underscore the potential of polyvalent nanobodies in combating viral infections.