Fig. 1
Host cell entry and neutralization sensitivity of the SARS-CoV-2 XBB.1.5 lineage. a Relative frequency of SARS-CoV-2 lineages BA.5* (without BQ.1*), BA.2.75*, BQ.1*, XBB* (without XBB.1.5*), and XBB.1.5* in selected countries (graphs are based on data retrieved from https://cov-spectrum.org/). b Mutations in the S proteins of SARS-CoV-2 lineages B.1, BA.4-5, BQ.1.1, XBB.1 and XBB.1.5 compared to the S protein of the Wuhan-Hu-01 isolate. The mutation highlighted in pink indicates the unique S protein mutation of the XBB.1.5 lineage that is not present in the S protein of the parental XBB.1 lineage. S protein mutations that are identical for all Omicron sublineages under study are indicated. NTD N-terminal domain, RBD receptor-binding domain, pre-S1/S2 region between RBD and the border between S1 and S2 subunits. c Cell line tropism and entry efficiency of the SARS-CoV-2 XBB.1.5 lineage. Identical volumes of pseudotype particles (pp) harboring the indicated SARS-CoV-2 S proteins were inoculated onto the indicated cell lines and pseudovirus entry was analyzed at 16–18 h postinoculation by measuring the activity of virus-encoded luciferase in cell lysates. Data represent the mean of six biological replicates (each performed with four technical replicates) and entry was normalized against B.1pp (=1; indicated by dashed line). Error bars indicate the standard error of the mean (SEM). Statistical significance was analyzed by two-tailed Student’s t-tests with Welch correction (not significant [ns], p > 0.05; *p ≤ 0.05; **p ≤ 0.01; ***p ≤ 0.001). Please also see Supplementary Fig. S1. d Impact of antibody-mediated ACE2 blockade on host cell entry of the SARS-CoV-2 XBB.1.5 lineage. Pseudotype particles harboring the indicated SARS-CoV-2 S proteins or VSV-G (control) were inoculated onto Vero cells that had been preincubated with ACE2-blocking anti-ACE2 antibody. At 16–18 h postinoculation, pseudovirus entry was analyzed and normalized against samples without antibody (=0% inhibition). Data represent the mean of three biological replicates (performed with four technical replicates). Error bars indicate the SEM. The top graph shows dose-dependent inhibition of pseudovirus entry, while the bottom graph shows area under the curve (AUC) data. Statistical significance was analyzed by two-tailed Student’s t-tests with Welch correction (not significant [ns], p > 0.05; *p ≤ 0.05; **p ≤ 0.01; ***p ≤ 0.001). e Sensitivity of the SARS-CoV-2 XBB.1.5 lineage to neutralization by monoclonal antibodies (mAb). Pseudotype particles harboring the indicated SARS-CoV-2 S proteins were preincubated with individual mAb or mAb cocktails, and subsequently inoculated onto Vero cells. At 16–18 h postinoculation, pseudovirus entry was analyzed and normalized against samples without mAb (=0% inhibition). Data represent the mean of three biological replicates (performed with four technical replicates). Error bars indicate the SEM. f Sensitivity of the SARS-CoV-2 XBB.1.5 lineage to neutralization by antibodies induced by vaccination or vaccination plus breakthrough infection (BTI). Pseudotype particles harboring the indicated SARS-CoV-2 S proteins were preincubated with plasma from (i) three-times vaccinated individuals with BTI during the BA.5 wave in Germany (n = 13), (ii) four-times vaccinated individuals that received the monovalent BNT162b2/Comirnaty vaccine booster (n = 10), or (iii) four-times vaccinated individuals that received the bivalent BNT162b2/Comirnaty Original/Omicron BA.4-5 vaccine booster (n = 13). Following incubation, the samples were inoculated onto Vero cells. At 16–18 h postinoculation, pseudovirus entry was analyzed, normalized against samples without plasma (=0% inhibition), and the neutralizing titer 50 (NT50), indicating the plasma dilution resulting in half-maximal inhibition, was calculated. Data represent geometric mean NT50 values (geometric mean titers, GMT) from a single biological replicate (conducted with four technical replicates). Information above the graphs indicates responder rates (=proportion of plasma samples with detectable neutralizing activity), GMT, and the fold change in GMT for BA.4-5pp, BQ.1.1pp, XBB.1pp, or XBB.1.5pp against B.1pp. Statistical significance was assessed by the Wilcoxon matched-pairs signed rank test (ns, p > 0.05; *p ≤ 0.05; **p ≤ 0.01; ***p ≤ 0.001). Please also see Supplementary Table S1 and Supplementary Fig. S2
