Filenews 18 March 2021
Neutralising antibodies produced after receiving mRNA vaccines for the new coronavirus appear to be less effective against mutated strains of SARS-CoV-2 and specifically against the Brazilian and South African strains of the virus. This alarming conclusion was reached by experts from the Ragon Institute at Massachusetts General Hospital, the Massachusetts Institute of Technology (MIT) and Harvard University, as reported in a publication in the journal Cell.
Up to 40 times more resistant to antibodies
The researchers, led by Dr. Alejandro Balac from the Ragon Institute who is also an assistant professor of Medicine at Harvard Medical School and a physician-researcher at Massachusetts General Hospital, used the experience they have gained on research into neutralizing antibodies against HIV in AIDS to analise how well antibodies work against the original strain of the new coronavirus and its new mutant strains. "When we checked the new strains against the neutralizing antibodies produced after vaccination, we discovered that three new strains first described in South Africa were 20-40 times more resistant to neutralizing antibodies. Two strains first described in Brazil and Japan were five to seven times more resistant than the original SARS–CoV-2 strain," noted Dr. Balach.
The key and the lock
The researcher explained that debilitating antibodies act by tying up the virus and blocking it from entering human cells. Antibodies and virus resemble the key and lock, the shapes of which must fit perfectly so that there is the perfect "bond" between them. If the shape of the virus changes to the point where the antibody is joined to it – in our case this point is the virus spike protein – then the antibody may no longer be able to recognize and neutralize the virus.
The RBD area
Scientists even saw, as Described by Wilfrido Garcia-Beltran from the Department of Pathology of Massachusetts General Hospital who was the first author of the new study, that mutations in a specific area of SARS-CoV-2's spike protein called the receptor tethering area (RBD) were more likely to help the virus be resistant to neutralizing antibodies. All three South African strains, which were also the most resistant to antibodies, shared three mutations in the RBD region. This may have contributed to the great resilience these strains show in neutralizing antibodies, the researchers noted.
The effectiveness of vaccines is not eliminated
They added, however, that although some mutated strains of the virus appear to be resistant to neutralising antibodies produced after vaccination, this does not mean that in practice vaccines will not be effective. "The body has other ways of immunoprotection than antibodies," Dr. Balats explained, adding: "Our findings do not necessarily mean that vaccines will not prevent COVID-19, but that the antibody-related immuno-response part may be an issue in identifying some of the new variants."
Valuable knowledge for the development of the new generation of vaccines
As with all viruses, SARS-CoV-2 is expected to continue to mutate as it spreads. Understanding which mutations are most likely to allow him to escape the immunity caused by vaccines will significantly help in the development of the new generation of vaccines that will protect against the new variant strains of the virus. It will also contribute to research into the development of vaccines that will in future offer broad protection against many strains of the virus, regardless of the mutations they will exhibit.
Source: news.in.gr
