Figure 4.

Serological binding and neutralizing capacity against SARS‐CoV and SARS‐CoV‐2 by NTD protein immunization (A) Binding of plasma from SARS‐CoV‐2 NTD protein immunized mice, SARS‐CoV NTD protein immunized mice, live SARS‐CoV‐2 immunized mice and live SARS‐CoV immunized mice against SARS‐CoV and SARS‐CoV‐2 NTD protein were measured by ELISA assay. The mean OD₄₅₀ values calculated after detecting each plasma sample in duplicate are shown. (B) Neutralization activities of plasma from mice immunized with SARS‐CoV‐2 NTD protein, SARS‐CoV NTD protein, live SARS‐CoV‐2 and live SARS‐CoV were measured. The value from each dot in the figure was tested by the means of two replicates in the same assay. (C) Binding of plasma from SARS‐CoV and SARS‐CoV‐2 NTD protein immunized mice against the full spike of SARS‐CoV‐2 or SARS‐CoV. (D) Binding of plasma from SARS‐CoV and SARS‐CoV‐2 NTD protein immunized mice against NL63‐Spike, 229E‐Spike, HKU1‐Spike and OC43‐Spike protein were tested by ELISA assay. The OD₄₅₀ value from each dot in the figure was taken by means of two replicates in the same experiment. p‐Values were caluated using two‐tailed t‐test. Error bars represent standard deviation. Each sample was tested as duplicates in each assay and the results were confirmed by two independent experiments.