Single-domain antibodies tackle COVID variants

[...]there are strong arguments in favour of developing alternative, nanobody-based therapeutics in response to evolving human respiratory viruses such as SARS-CoV-2. Since the virus began infecting people more than a year ago, the collective human neutralizing-antibody response generated against SARS-CoV-2 has applied a strong selection pressure on the spike-protein RBD. [...]only two or three amino-acid-residue changes in versions of the virus that became dominant during the second and third waves of the pandemic were enough to render those versions substantially more resistant to neutralization by antibodies generated during the first wave - as assessed by tests on blood samples, known as convalescent serum, from individuals who have had COVID-19 (ref. 7). The authors' evidence indicates that these engineered antibodies could potently neutralize all of the tested SARS-CoV-2 variants of concern (viruses with RBD mutations and which were associated with the second and third waves of the pandemic). [...]the proteins from nanomice recognized evolutionarily conserved epitopes on the RBD that do not overlap with regions commonly recognized by human antibodies.