Neutralisation sensitivity of SARS-CoV-2 lineages EG.5.1 and XBB.2.3.

Viruses belonging to the XBB sublineage of the SARS-CoV-2 omicron variant circulate globally and pose a health threat, particularly to high-risk groups, including patients who are immunocompromised. At present, descendants of the XBB.1.9.2 lineage, EG.5 and EG.5.1 (appendix pp 8–10), are becoming dominant in multiple countries,1Chen C Nadeau S Yared M et al.CoV-Spectrum: analysis of globally shared SARS-CoV-2 data to identify and characterize new variants.Bioinformatics. 2022; 38: 1735-1737Crossref Scopus (82) Google Scholar and the EG.5 lineage has recently been declared a variant of interest by WHO.2WHOEG.5 initial risk evaluation.https://www.who.int/docs/default-source/coronaviruse/09082023eg.5_ire_final.pdf?sfvrsn=2aa2daee_1Date: Aug 9, 2023Date accessed: August 12, 2023Google Scholar Furthermore, infections with another XBB sublineage, XBB.2.3, are on the rise (appendix pp 8–10).1Chen C Nadeau S Yared M et al.CoV-Spectrum: analysis of globally shared SARS-CoV-2 data to identify and characterize new variants.Bioinformatics. 2022; 38: 1735-1737Crossref Scopus (82) Google Scholar The EG.5.1 and XBB.2.3 lineages both harbour unique combinations of spike (S) protein mutations (appendix pp 11–12). Although a preliminary analysis indicated no difference in risk of hospitalisation among XBB subvariants including XBB.2.3,3Pung R Kong XP Cui L et al.Severity of SARS-CoV-2 omicron XBB subvariants in Singapore.Lancet Reg Health West Pac. 2023; 37100849Google Scholar information on key biological properties of these lineages is not available. We investigated cell entry and neutralisation sensitivity of EG.5.1 and XBB.2.3 using pseudotyped particles (pp), which adequately model SARS-CoV-2 cell entry and its neutralisation.4Schmidt F Weisblum Y Muecksch F et al.Measuring SARS-CoV-2 neutralizing antibody activity using pseudotyped and chimeric viruses.J Exp Med. 2020; 217e20201181Crossref Google Scholar Particles bearing S proteins of B.1 (derived from a virus circulating early in the pandemic; B.1pp), XBB.1.5, or XBB.1.16 (XBB1.5pp, XBB.1.16pp) were included for comparison. All particles efficiently entered all cell lines analysed; however, minor differences in entry efficiency were noted. Thus, EG.5.1pp and XBB.2.3pp entered several cell lines with lower efficiency than XBB.1.5pp and XBB.1.16pp (1·5–2·8-fold [293T], 1·3–1·6-fold [Caco-2], and 1·3–2·0-fold [Calu-3] reduction; appendix pp 8–10). In turn, Calu-3 and Caco-2 cell entry of XBB.1.5pp and XBB.1.16pp was 1·8–2·4-fold lower than that measured for B.1pp (appendix pp 8–10), in keeping with published data.5Meng B Abdullahi A Ferreira IATM et al.Altered TMPRSS2 usage by SARS-CoV-2 omicron impacts infectivity and fusogenicity.Nature. 2022; 603: 706-714Crossref PubMed Scopus (432) Google Scholar, 6Willett BJ Grove J MacLean OA et al.SARS-CoV-2 omicron is an immune escape variant with an altered cell entry pathway.Nat Microbiol. 2022; 7: 1161-1179Crossref PubMed Scopus (161) Google Scholar, 7Nehlmeier I Kempf A Arora P et al.Host cell entry and neutralisation sensitivity of the SARS-CoV-2 XBB.1.16 lineage.Cell Mol Immunol. 2023; 20: 969-971Crossref Scopus (3) Google Scholar, 8Hoffmann M Arora P Nehlmeier I et al.Profound neutralization evasion and augmented host cell entry are hallmarks of the fast-spreading SARS-CoV-2 lineage XBB.1.5.Cell Mol Immunol. 2023; 20: 419-422Crossref PubMed Scopus (10) Google Scholar In addition, no differences in ACE2 dependency of XBB.1.5pp, XBB.1.16pp, EG.5.1pp, and XBB.2.3pp were observed when Vero cells were treated with ACE2-blocking antibody before infection (appendix pp 8–10). Next, we assessed EG.5.1pp and XBB.2.3pp neutralisation by therapeutic antibodies. All S protein-bearing particles were efficiently inhibited by sotrovimab (Xevudy, GlaxoSmithKline, London, UK), with inhibition of particles bearing XBB S proteins being less efficient as compared with B.1pp (appendix pp 8–10). In contrast, LY-CoV1404 (Bebtelovimab, Eli Lilly, Indianapolis, IN, USA) as well as a combination of AZD1061 and AZD8895 (also known as cilgavimab and tixagevimab, respectively, and marketed as Evusheld by AstraZeneca, Cambridge, UK) neutralised B.1pp but not particles bearing XBB S proteins (appendix pp 8–10). Finally, we investigated neutralisation by plasma from quadruple vaccinated people collected 2 months (cohort one) or 4–8 (cohort two) months after vaccination, or from people who were vaccinated three to four times with breakthrough infection (cohort three). Particles bearing XBB S proteins were generally less well neutralised as compared with B.1pp (15–194-fold reduction; appendix pp 8–10). No major differences were observed between neutralisation of XBB.1.5pp, XBB.1.16pp, and XBB.2.3pp. However, it is noteworthy that EG.5.1pp evaded neutralisation by plasma collected for cohorts one and three with higher efficiency than XBB.2.3pp, XBB.1.5pp, and XBB.1.16pp. Our results suggest that the rise of EG.5 and EG.5.1, as well as XBB.2.3, infections might not be due to an increased capacity of these viruses to enter target cells; although, our findings await confirmation with authentic virus and primary cells. Of the few therapeutic antibodies still considered useful in the clinic, sotrovimab inhibited both EG.5.1pp and XBB.2.3pp, at least at high concentrations. Finally, we obtained evidence that EG.5.1 evades neutralising antibodies with increased efficiency, at least in the context of the immune background of the plasma donors analysed. AK, IN, SP, and MH did the contract research (testing of vaccinee sera for neutralising activity against SARS-CoV-2) for Valneva, unrelated to this work. GMNB served as an adviser for Moderna, unrelated to this work. SP served as an adviser for BioNTech, unrelated to this work. AD-J served as an adviser for Pfizer, unrelated to this work. All other authors declare no competing interests. SP acknowledges funding by the EU project UNDINE (grant agreement number 101057100), the Ministry for Science and Culture of Lower Saxony (Niedersächsisches Ministerium für Wissenschaft und Kultur; 14-76103-184, COFONI Network, projects 7FF22, 6FF22, 10FF22) and the German Research Foundation (Deutsche Forschungsgemeinschaft; PO 716/11-1). H-MJ received funding from BMBF (01KI2043, NaFoUniMedCovid19-COVIM: 01KX2021), Bavarian State Ministry for Science and the Arts, and Deutsche Forschungsgemeinschaft through the research training groups RTG1660 and TRR130, the Bayerische Forschungsstiftung (Project CORAd) and the Kastner Foundation. GMNB acknowledges funding by German Center for Infection Research (grant 80018019238). GMNB and AD-J acknowledge funding by a European Regional Development Fund (Defeat Corona, ZW7-8515131). The funding sources had no role in the design and execution of the study, the writing of the manuscript, and the decision to submit the manuscript for publication. The authors did not receive payment by a pharmaceutical company or other agency to write the publication. The authors were not precluded from accessing data in the study, and they accept responsibility to submit for publication. Download .pdf (1.62 MB) Help with pdf files Supplementary appendix