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Fig. 1 | Virology Journal

Fig. 1

From: Sequential immunization with SARS-CoV-2 RBD vaccine induces potent and broad neutralization against variants in mice

Fig. 1

Potent and broad neutralization against SARS-CoV-2 variants elicited by sequential immunization with a wild-type inactivated vaccine and a mutant RBD subunit vaccine in mice. a Schematic diagram of the RBD dimer vaccine named I-P-R-F [6]. The structural elements show IFNα, Pan-DR epitope (PADRE), RBD, and immunoglobulin Fc fragment. The RBD regions of three kinds of I-P-R-F, including WT and Beta and Delta variants, are shown on the right, and mutations are labeled as sticks. b Schematic representation of the immunization schedule and blood sample collection of mice in 8 groups (Groups A-H, n = 10 in each group). c Schematic representation of mutations located in viral spike proteins of the Beta, Delta, Alpha, Iota, Kappa, and A.23.1 variants. d Neutralization titers against SARS-CoV-2 WT and variants of vaccine-elicited mouse serum. The data are shown for different pseudoviruses. e Neutralization titers against SARS-CoV-2 WT and variants of vaccine-elicited mouse serum. The data are shown for different groups and all comparisons are made to the WT readings. Geometric mean titers, in ID50 values, were calculated and are written in each column. The error bars are standard deviations, and the symbols represent individual mice. The dotted line indicates the limit of detection (1:40 dilution) for the assay. Non-neutralizing serum was assigned a value of one-half of the limit of detection for visualization (1:20 dilution). Statistical analysis was performed with paired or unpaired t tests using GraphPad Prism 8.0 software. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001

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