New SARS-CoV-2 variants are spreading rapidly, and there are fears that Covid vaccines won’t protect against them. The latest structural studies of the SARS-CoV-2 variants spike protein, led by Bing Chen, Ph.D., at Boston Children’s Hospital, says new properties of the Alpha and Beta variants. It also suggests that the current vaccines may be less effective against the Beta variant.
On the surface of SARS, CoV-2 spike protein enables the virus to attach to and enter our cells. All the current vaccines are directed against them. On June 24, the new study published in Science used cryoelectron microscopy to compare the spike protein from the original virus with the Alpha and Beta variants. At a specific location, the structural findings indicate that mutations in the Beta variant change the shape of the spike surface. As a result, neutralizing antibodies induced by current vaccines cannot bind to the Beta virus, which may allow it to avoid the immune system even when people are vaccinated.
According to Chen, from the Molecular Medicine Division at Boston Children’s, “The mutations make antibodies stimulated by the current vaccine less effective. The Beta variant is somewhat resistant to the current vaccines, and we think a booster with the new genetic sequence can be beneficial for protecting against this variant.”
The study also found that that mutation in the Beta variant makes the spikeless effective in binding to ACE2. This suggests that this variant is less transmissible than the Alpha variant. The study confirms that the Alpha variant genetic change in the spike helps the virus bind better to ACE2 receptors and makes it more infectious. It is indicated by testing that antibodies elicited by existing vaccines can still neutralize this variant.
According to the researcher, to be a heightened threat, a SARS-CoV-2 variant would need to do three things: cause more severe disease, evade the immune system in vaccinated people or those previously exposed to Covid, spread more quickly. The Beta and Alpha variants do not meet all these criteria.