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. 2023 Mar 5;26(4):106335. doi: 10.1016/j.isci.2023.106335

Figure 5.

Figure 5

Use of nucleoprotein as an antigen and test for the requirement of signal peptides

(A) A schematic drawing of antigen structure. EXG-5004: c-srRNA3 encodes the nucleoprotein (N) protein of SARS-CoV-2 (original strain). EXG-5005: c-srRNA3 encodes a fusion protein of signal peptide sequence of the human CD5 protein and the nucleoprotein (N) protein of SARS-CoV-2 (original strain).

(B–G) Cellular immunity by ELISpot assays, showing the frequency of IFN-γ spot-forming cells (SFC) or IL-4 SFC in 1 × 10ˆ6 splenocytes obtained from CD-1 outbred mice or BALB/c inbred mice that were immunized by a single intradermal injection of 100 μL solution containing either 5 μg or 25 μg of EXG-5004, EXG-5005, or a placebo (PBO: buffer only). The splenocytes were restimulated by culturing in the presence and absence of a pool of 15mer peptides for nucleoprotein of SARS-CoV-2 (original strain). The frequency obtained in the presence of peptides is plotted in the graph after subtracting the frequency obtained in the absence of peptides (background). The average and standard deviation (error bars) of five mice (n = 5) are shown for each group. (B) CD-1 mouse, EXG-5004, IFN-γ. (C) CD-1 mouse, EXG-5004, IL-4. (D) CD-1 mouse, EXG-5005, IFN-γ. (E) CD-1 mouse, EXG-5005, IL-4. (F) BALB/c mouse, EXG-5005, IFN-γ. (G) BALB/c mouse, EXG-5005, IL-4.