Superimmunity by pan-sarbecovirus nanobodies

Area of Science:

• Immunology
• Virology
• Structural Biology

Background:

• Vaccine boosters and infection enhance SARS-CoV-2 antibody potency and breadth.
• Camelids can develop potent antibody responses to viral antigens.

Purpose of the Study:

• To isolate and characterize ultra-high-affinity nanobodies with broad activity against sarbecoviruses.
• To investigate the structural basis for the broad neutralization activity of these nanobodies.

Main Methods:

• Integrative proteomics to isolate nanobodies from an immunized camelid.
• In vitro neutralization assays against SARS-CoV, SARS-CoV-2, and variants.
• Structural determination of nanobody-RBD/spike complexes.

Main Results:

• Isolation of a large repertoire of ultra-high-affinity pan-sarbecovirus nanobodies (psNbs).
• psNbs demonstrated high efficacy against SARS-CoV, SARS-CoV-2, and Omicron variants, with median neutralization potency in the single-digit nanograms per milliliter.
• Development of an inhalable, bispecific psNb (PiN-31).
• Structural analysis revealed five epitope classes targeting conserved, flexible regions of the RBD.

Conclusions:

• Camelid-derived nanobodies can provide broad and potent protection against sarbecoviruses.
• Targeting conserved RBD epitopes is a promising strategy for developing universal coronavirus therapeutics.
• The structural insights provide a foundation for designing next-generation antiviral agents.