Small But Mighty

SARS-CoV-2 infects human cells using its surface spike proteins (one shown here, coloured blue). Neutralising antibodies – either produced naturally during infection, induced by vaccination, or lab-generated as monoclonal antibody (mAb) treatments – typically target this protein’s large, outermost S1 domain, rather than the small, less accessible S2 domain tucked behind. The S1 region is highly mutable, however, which partly explains why vaccines provide reduced protection over time and why existing mAbs have become largely ineffective. Now, there’s a new mAb (red) in the works – one that targets the far less mutable S2 region. To generate this mAb, scientists turned to llamas, which, like all camelids and unlike other mammals, produce tiny single-domain antibodies, or nanobodies, that can squeeze into places other antibodies can’t. Encouragingly, this new nanobody mAb had strong potency in culture against multiple variants of SARS-CoV-2 as well as SARS-CoV-1, and could significantly reduce viral load in SARS-CoV-2-infected rodents.

Written by Ruth Williams

Ruth Williams

Writer

Ruth is a freelance science journalist based in the US. She's a regular correspondent for The Scientist, and her work has appeared in The Lancet, Nature, Scientific American Mind, BBC Focus and elsewhere. Twitter @rooph

Website

• Image from the Vlaams Instituut voor Biotechnologie; relating to work by Sieglinde De Cae et al
• VIB Center for Medical Biotechnology, VIB, Ghent, Belgium
• Image in the public domain
• Research published in Nature Communications, May 2025