Fig 4. A non-RBD epitope neutralizes the cell entry of SARS-CoV-2 Omicron variant.

(A) Pseudovirus entry assay shows that Nanosota-5-Fc neutralizes the cell entry of three Omicron subvariants. Error bars represent SEM (n = 4). IC₅₀ values were calculated for each of the three Omicron subvariants. (B) Cell-cell fusion assay shows that Nanosota-5-Fc decreases XBB.1.5-spike-mediated cell-cell fusion (left), but increases prototypic-spike-mediated cell-cell fusion (right). Spike-expressing cells and ACE2-expressing cells were incubated together for fusion in the presence of various concentrations of Nanosota-5-Fc. Comparisons of cell-cell fusion between the negative control (PBS buffer) and various concentrations of Nanosota-5-Fc were performed using an unpaired two-tailed Student’s t-test. Error bars represent SEM (n = 4). ***p<0.001; **p<0.01. **p<0.05. NS: not statistically significant. (C) Nanosota-5-Fc neutralizes cell infection by live Omicron subvariants. The efficacy of Nanosota-5-Fc against Omicron subvariants was calculated and expressed as the concentration capable of maintaining the cell viability by 50% (IC₅₀) compared to control virus. Error bars represent SEM (n = 4).