BA.2.75 について

最近になって新たに出現した変異株 BA.2.75 にギリシャ神話から採った

抗体治療薬 bebtelovimab ――日本はキープできてんのかな?

Evasion of neutralizing antibodies by Omicron sublineage BA.2.75【bioRxiv 2022年7月20日】


Towards the end of 2021, SARS-CoV-2 vaccine effectiveness was threatened by the emergence of the Omicron clade (B.1.1.529), with more than 30 mutations in spike. Recently, several sublineages of Omicron, including BA.2.12.1, BA.4, and BA.5, have demonstrated even greater immune evasion, and are driving waves of infections across the globe.

One emerging sublineage, BA.2.75, is increasing in frequency in India and has been detected in at least 15 countries as of 19 July 2022. Relative to BA.2, BA.2.75 carries nine additional mutations in spike. Here we report the sensitivity of the BA.2.75 spike to neutralization by a panel of clinically-relevant and pre-clinical monoclonal antibodies, as well as by serum from blood donated in Stockholm, Sweden, before and after the BA.1/BA.2 infection wave.

BA.2.75 does not show greater immune evasion than the currently-dominating BA.5 in our set of serum samples, and exhibits moderate susceptibility to tixagevimab and cilgavimab that form a widely used monoclonal antibody cocktail (Evusheld).

Neutralization sensitivity of Omicron BA.2.75 to therapeutic monoclonal antibodies【bioRxiv 2022年7月15日】


Since the end of 2021, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant outcompeted other variants and took over the world. After the emergence of original Omicron BA.1, Omicron BA.2 subvariant emerged and outcompeted BA.1. As of July 2022, some BA.2 subvariants, including BA.2.12.1, BA.4 and BA.5, emerged in multiple countries and begun outcompeting original BA.2. Moreover, a novel BA.2 subvariant, BA.2.75, was detected in eight countries including India at the end of June 2022, and preliminary investigations suggest that BA.2.75 is more transmissible over the other BA.2 subvariants. On July 7, 2022, the WHO classified BA.2.75 as a variant-of-concern lineage under monitoring. We have recently demonstrated that BA.4/5 is highly resistant to a therapeutic monoclonal antibody, cilgavimab, than BA.2. The resistance of SARS-CoV-2 variants to therapeutic antibodies can be attributed to the mutations in the viral spike protein. Compared to the BA.2 spike, BA.2.12.1 and BA.4/5 respectively bear two and four mutations in their spike proteins. On the other hand, the majority of BA.2.75 spike bears nine substitutions. The fact that the mutation number in the BA.2.75 spike is larger than those in the BA.4/5 spike raises the possibility that the BA.2.75 spike significantly reduces sensitivity towards therapeutic monoclonal antibodies than BA.2 and BA.4/5. In this study, we generated pseudoviruses harboring the spike proteins of BA.2.75, BA.4/5 and BA.2 and evaluated the efficacy of ten therapeutic monoclonal antibodies and three antibody cocktails against BA.2.75.

Neutralizing antibody evasion and receptor binding features of SARS-CoV-2 Omicron BA.2.75【bioRxiv 2022年7月19日】


The Omicron subvariants BA.2.75 is rapidly raising in India. BA.2.75 also shows a local growth advantage compared to BA.2.38 and BA.4/BA.5. Its immune evasion capability and receptor binding affinity is unclear and requires investigation. Here, we show that BA.2.75 is more neutralization evasive than BA.2.12.1 against the plasma from post-vaccination BA.2 infection, but less compared to BA.4/BA.5. However, as shown in a small sample of plasma from post-vaccination Delta infection, BA.2.75 seems to be more immune evasive than BA.4/BA.5 in Delta-stimulated immune background, which may explain BA. 2.75’s growth advantage over BA.4/BA.5 in India. The additional N460K, G446S, D339H and R493Q mutations carried by BA.2.75 allows it to escape BA.2-effective neutralizing antibodies of different RBD epitopes, and BA.2.75 has a distinct antibody escaping profile from BA.4/BA.5. Compared to BA.2, REGN10933 and COV2-2196 partially recovered neutralization against BA.2.75 due to R493Q reversion. However, the efficacy of their corresponding cocktail was not significantly changed, since REGN10987 and COV2-2130 showed reduced neutralizing activity due to G446S. BA.2.75 exhibits higher ACE2-binding affinity than BA.4/BA.5, which should be contributed by R493Q and N460K, according to deep mutational scanning (DMS) results. This affinity-strengthening feature is being further examined and verified, which will be updated soon.