Virological characterization of XBB.1.16

In a recent study posted on Bio Rxiv* In a preprint server, researchers perform a large multiscale survey to investigate the virological characterization of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron XBB subvariant, XBB.1.16 To do.

study: Virological characterization of the SARS-CoV-2 Omicron XBB.1.16 variant. Image Credit: Limbitech / Shutterstock.com

*Important Notices: Bio Rxiv We publish a non-peer-reviewed, preliminary scientific report and should not be taken as conclusive, to guide clinical practice/health-related actions, or to be treated as established information.

Background

The SARS-CoV-2 XBB.1.16 variant has 1.27-fold and 1.17-fold higher effective reproductive numbers (R_e) demonstrating the ability of this new Omicron variant to spread rapidly compared to the XBB.1 and XBB.1.5 subvariants, respectively.

As a result of this increased infectivity, the World Health Organization (WHO) began monitoring XBB.1.16 on 30 March 2023 after it was detected in several countries, including India. Previously, SARS-CoV-2 Omicron XBB subvariants with the F486P substitution in the spike (S) protein were widely distributed worldwide, including XBB.1.5 and XBB.1.9.

Investigation result

The current analysis shows that, compared with its predecessor mutant, XBB.1.16 has two S substitutions in the N-terminal domain (NTD) and receptor binding domain (RBD), including E180V and T478R, respectively. was shown. Furthermore, the dissociation constant (K_D.) XBB.1.16 RBD of the host receptor angiotensin-converting enzyme 2 (ACE2) was 2.4-fold higher than XBB.1.5. However, her K_D. The values ​​are significantly lower than those of XBB.1, reflecting the binding affinity of this new subvariant.

fake virus Assays showed that the infectivity of XBB.1.16 was comparable to that of XBB.1, but unlike XBB.1.5, the latter was more infectious than the parental XBB.1 mutant. Note that the S: T478R and S: E180V substitution mutations greatly affect the infectivity of this virus mutant. The S: T478R mutation increases the infectivity of XBB.1.16, whereas the S: E180V substitution significantly reduced its viral infectivity.

XBB.1.16 may have acquired these two S protein mutations simultaneously as a strategy to evolve. This behavior has been previously observed in other Omicron subvariants such as BA.5 and XBB.1. In fact, XBB.1.16 follows the evolutionary path of previously emerged Omicron subvariants.

Regarding susceptibility to sera, neutralization assays showed that XBB.1.16 was highly resistant to sera from individuals reinfected with Omicron BA.2/BA.5, 18 more than Omicron B.1.1/B.1.1. It was shown to be 3-fold and 37-fold resistant. However, the susceptibility of this variant to convalescent sera from XBB.1-infected hamsters was similar to the XBB.1/XBB.1.5 mutant.

XBB.1.16 was highly resistant to all six clinically available monoclonal antibodies against SARS-CoV-2. Only sotrovimab showed antiviral activity against his XBB.1.16. However, this effect was weak. Finally, antigen mapping showed that XBB.1.16 has similar antigenicity to her XBB.1. However, this trait is quite different from that associated with his XBB.1.5.

Conclusion

Overall, the current extensive exploratory analysis indicates that the SARS-CoV-2 Omicron XBB.1.16 subvariant has the potential to spread and infect a wider population worldwide than the XBB.1 and XBB.1.5 subvariants. turned out to be very high. Furthermore, XBB.1.16 exhibits a high immune evasion capacity similar to XBB.1 and XBB.1.5.

The authors reasoned that XBB.1.16 enjoyed higher fitness and growth advantages due to a different antigenicity than XBB.1.5. In addition, mutations in non-S SARS-CoV-2 proteins may also contribute to their high fitness.

*Important Notices: Bio Rxiv We publish a non-peer-reviewed, preliminary scientific report and should not be taken as conclusive, to guide clinical practice/health-related actions, or to be treated as established information.