‘The Great Escape’ by SARS-CoV-2 XBB.1

In a recent article published in lancet microbe, Dutch and British researchers quantify the antigenic diversity of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) subvariants, BQ.1.1, BM.1.1.1, and XBB.1 Did. These are all variant derivatives. Omicron (VOC) emerging in late 2022.

correspondence: Antigen mapping of novel SARS-CoV-2 omicron variants BM.1.1.1, BQ.1.1 and XBB.1Image Credit: NIAID

Background

It is of great concern that new subvariants of Omicron are emerging at an alarming rate, even though large segments of the world’s population have been vaccinated and acquired immunity induced by previous infections.

About research

In the present study, researchers used antigenic mapping to simultaneously quantify and visualize the antigenic properties of SARS-CoV-2 variants.Researchers use this multidimensional scaling method extensively to confirm antigen Position relative to antiserum sample, both directly correspond Neutralizing antibody titer.

They used the SARS-CoV-2 hamster model for their experiments. First, they infected test animals with an Omicron BA.5 subvariant that is genetically close to Omicron BA.2, but differed by his two deletions and three substitutions in the spike (S) amino acid sequence. . They then assessed neutralizing antibody titers for all serum samples and variants, including Omicron BA.5, BM.1.1.1, BQ.1.1, and XBB.1.

Results and conclusions

The updated antigen map so generated shows that all omicron subvariants are spaced apart from pleomicron subvariants, with one antigen unit reflecting a two-fold decrease in neutralization titer. is showing. Specifically, only homologous variants, BA.5 and BA.2, retained antigenic positions within one antigenic unit of his, whereas the remaining Omicron subvariants were 2.3–7 antigenic units apart from each other. retained the same antigenic position.

Furthermore, the study data revealed that Omicron BA.5 antiserum samples substantially neutralized BA.2 and BQ.1.1, but not Omicron BM.1.1.1. Surprisingly, none of the serum samples effectively neutralized Omicron XBB.1. In both two-dimensional (2D) and three-dimensional (3D) maps, Omicron XBB.1, BM.1.1.1, and BQ.1.1 are the most distant from all previous variants and have higher dimensionality. no significant improvement was observed. The researchers observed a correlation between antigen map distances and antibody neutralization titers, showing remarkable accuracy in localizing antigen and serum samples. Also, BQ.1.1, XBB.1, and BM.1.1.1 had the lowest neutralization titers, followed by he Omicron BA.5 and BA.1/BA.2, which are ancestral SARS-CoV I also noted the reduction compared to the D614G. -2 Strain.

In conclusion, none of the new omicron subvariants clustered close to each other on the antigen map. Thus, despite the antigenic similarity between BQ.1.1 and BA.5, immunological imprinting may prevent her from neutralizing BQ.1.1 with a BA.5-based bivalent vaccine. I have. In addition, vaccines based on any of the Omicron subvariants may weakly cross-neutralize SARS-CoV-2 variants that have not yet emerged, and they may be antigenically equivalent or more distant. . Therefore, it is important to continuously map new SARS-CoV-2 variants and understand their evolutionary trajectory to inform the development of future he COVID-19 vaccine candidates.

Antigenic distance mapping of XBB.1 (among other things):
“We observed that post-vaccination human neutralization titers reflected the antigenic map as the greatest reduction in neutralization titers compared to the D614G variant.” https://t.co/epa5txNqqw @LancetMicrobe @bart_haagmans pic.twitter.com/oEIeUKt8HR

— Eric Topol (@EricTopol) January 17, 2023

The Great Escape by XBB.1

Research from the Erasmus Medical Center in Rotterdam

Shows how new versions of the virus evade antibodies produced by previous versions and vaccines

Graph shows accumulated mutations in different parts spike protein

1/3 https://t.co/T9aRY0NYBE pic.twitter.com/eM9nWPY8R5

— Rajeev Jayadevan (@RajeevJayadevan) January 17, 2023