The B.1.351 and B.1.1.7 SARS-CoV-2 variants (first detected in South Africa and the UK, respectively) show increased resistance to antibody neutralization in laboratory experiments, a Nature study reveals. The findings suggest that current antibody therapies and vaccines may be less effective against some variants of the virus.
Monoclonal antibodies, which target specific sites on the SARS-CoV-2 virus, are being used in hospitals to treat COVID-19. However, these therapeutics were designed to work against the initial variant of SARS-CoV-2, which emerged in 2019.
David Ho and colleagues assessed the ability of 30 monoclonal antibodies, along with plasma from 20 patients who recovered from COVID-19 and sera from 22 people who have been vaccinated, to neutralize the B.1.351 and B.1.1.7 variants of SARS-CoV-2. The authors found that the B.1.1.7 variant was resistant to neutralization by monoclonal antibodies that target the N-terminal domain of the spike protein and was relatively resistant to some antibodies that target the receptor-binding domain. However, it was not resistant to plasma from patients who had recovered from COVID-19 and sera from individuals who were vaccinated, and the authors suggest that this variant will not have a marked impact on current therapies or vaccines.
However, in addition to resistance to neutralization by antibodies to the N-terminal domain, the B.1.351 variant was found to be resistant to a group of monoclonal antibodies that is currently used in therapies that target the receptor-binding motif of the spike protein, which was primarily attributed to the E484K mutation. The neutralizing activity of plasma from patients who had recovered from COVID-19 and sera from people who had been vaccinated was reduced by approximately 9- and 10–12-fold, respectively, against this variant.
The variant discovered in Brazil, known as P.1 or 501Y.V3, shares key mutations with B.1.351 and, although it was not included in this study, the authors suggest that it may show a similar pattern of resistance to the B.1.351 variant. They argue that SARS-CoV-2 is mutating in a direction that may cause it to evade current interventions that are directed against the viral spike protein; in which case, revised therapeutics would be needed. They conclude that these considerations underscore the need to stop virus transmission as quickly as possible, by redoubling mitigation measures and expediting vaccine rollout.
The paper is available at the following link: https://www.nature.com/articles/s41586-021-03398-2
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