The novel coronavirus has caused a global COVID-19 disease pandemic. COVID-19 virus is part of the betacoronavirus genus, which includes SARS-CoV and MERS-CoV. Scientists have now discovered a pair of neutralizing antibodies from a patient who recovered from COVID-19. Neutralizing antibodies bind to the SARS-CoV-2 spike protein, which blocks the protein’s ability to bind to the ACE2 receptor and allow the virus access to host cells.
Preliminary tests of the antibodies in mice showed a reduction of virus titers, which means that the antibodies may have therapeutic benefits and could also provide the building blocks for a COVID-19 vaccine. Yan Wu and his colleagues named the antibodies B38 and H4, and these antibodies can simultaneously bind to different epitopes (the part of an antigen to which the antibody attaches) on the spike protein’s Receptor Binding Domain (RBD). This suggests that when combined, the antibodies have a stronger neutralizing effect on the virus than either antibody by itself.
This discovery also suggests that if one of the viral epitopes mutates in a way that prevents the antibody's ability to bind, it may not affect the neutralizing ability. Wu and the team imaged the spike protein’s structure and confirmed that B38 binds to a subset of amino acids bound by ACE2 in the RBD. The study authors theorize that a mix of both antibodies could directly benefit COVID-19 patients, and the new information about the spike epitopes could lead to a SARS-CoV-2 vaccine.