Research press release



SARS-CoV-2: B.1.351 and B.1.1.7 variants more resistant to antibody neutralization in the laboratory

重症急性呼吸器症候群コロナウイルス2(SARS-CoV-2)のB.1.351変異株(南アフリカ共和国で最初に検出された)とB.1.1.7変異株(英国で最初に検出された)は、抗体による中和に対する抵抗性が高まっていることが実験室での実験によって明らかになった。この知見は、現在の抗体療法とワクチンの効果が、SARS-CoV-2の変異株の一部に対して弱い可能性を示唆している。この研究結果を報告する論文が、Nature に掲載される。


今回、David Hoたちは、30種類のモノクローナル抗体、COVID-19から回復した20人の患者の血漿、ワクチン接種を受けた22人の血清を調べて、これらがSARS-CoV-2の変異株(B.1.351変異株とB.1.1.7変異株)を中和する能力を評価した。その結果、B.1.1.7変異株は、スパイクタンパク質のN末端ドメインを標的とするモノクローナル抗体による中和に対して抵抗性を示し、受容体結合ドメインを標的とする一部の抗体に対する抵抗性は比較的に高かったが、COVID-19から回復した患者の血漿とワクチン接種を受けた患者の血清には抵抗性を示さないことが分かった。Hoたちは、B.1.1.7が現在の治療法やワクチンに顕著な影響を及ぼさないだろうと示唆している。



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:

doi: 10.1038/s41586-021-03398-2

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