Fig. 2 | Cellular & Molecular Immunology

Fig. 2

From: Key residues of the receptor binding motif in the spike protein of SARS-CoV-2 that interact with ACE2 and neutralizing antibodies

Fig. 2

The antibody response induced by recombinant RBD of SARS-CoV and SARS-CoV-2 in mice. a Schematic of the vaccine regimen. Five C57BL/6 mice per group were immunized two times (2–3 weeks apart) intramuscularly with 25 µg of the SARS CoV-2 RBD-hFc or SARS CoV RBD-hFc protein in combination with quick adjuvant. Mice immunized without the RBD protein but with hIgG were included as controls. Mice were sacrificed on day 35 after immunization, and antisera were collected for subsequent tests. b Cross-reactivity of SARS-CoV-2-RBD- or SARS-CoV-RBD-specific mouse sera against the SARS-CoV RBD or SARS-CoV-2 RBD as determined by ELISA. Mouse antisera were serially diluted three-fold and tested for binding to the SARS-CoV RBD or SARS-CoV-2 RBD. The IgG antibody (Ab) titres of SARS-CoV-2 antisera (red), SARS-CoV antisera (blue) and control antisera (black) were calculated at the endpoint dilution that remained positively detectable for the SARS-CoV-2 RBD or SARS-CoV RBD. The data are presented as the mean A450 ± s.e.m. (n = 5). c Cross-competition of SARS-CoV-2-RBD- or SARS-CoV-RBD-specific mouse sera and hACE2 with the SARS-CoV RBD or SARS-CoV-2 RBD as determined by ELISA. The data are presented as the mean blocking (%) ± s.e.m. (n = 5). Fifty percent blocking antibody titres (BT50) against the SARS-CoV pseudo-typed virus or SARS-CoV pseudo-typed virus were calculated. d Cross-neutralization of SARS-CoV-2-RBD- or SARS-CoV-RBD-specific mouse sera against SARS-CoV-2 or SARS-CoV pseudo-typed virus entry, measured by pseudo-typed virus neutralization assay. The data are presented as the mean neutralization (%) ± s.e.m. (n = 5). Fifty percent neutralizing antibody titres (NT50) against the SARS-CoV-2 or SARS-CoV pseudo-typed virus were calculated

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