Fig. 7
Neutralizing antibody responses were elicited against SARS-CoV-2 isolate Wuhan-Hu-1 and variants, including B.1.351, B.1.617.2, C.37, B.1.1.529, BA.1, BA.2, BA.5, and BQ.1.1 by double-layered N-S1 PNp vaccination in mice. A Representative SPR sensorgram showing binding kinetics of SARS-CoV-2 WT and its four variants S1 protein to immobilized mouse IgG from serum 21 days after boost immunization with N-S1 PNp (n = 8). The actual binding (color) and the optimal fit of data to a 1:1 binding model (black) are displayed, along with corresponding KD values. B The endpoint titers of serum binding to SARS-CoV-2 WT and its four variants of S1 protein were evaluated using indirect ELISA. C The pVNT50 of SARS-CoV-2 spike pseudovirus, including WT, B.1.617.2, B.1.1.529, BA.1, BA.2, BA.5, and BQ.1.1 were measured 3 weeks after the final N-S1 PNp vaccination for serum neutralizing antibody titers. Bars represent the mean ± SD of triplicate assays. Statistical significance was conducted using one-way ANOVA analysis followed by multiple comparisons post hoc tests, with corresponding P values displayed in bar charts. ***p-value < 0.001, **p-value < 0.01, *p-value < 0.05, nsp-value > 0.05