SARS-CoV-2 Vaccine CD8+ and CD4+ T-cell Responses

Example 12

CD8+activation by both S and N: CD80+splenocytes from hAd5 S-Fusion+N-ETSD vaccinated mice exposed to S peptide pool 1 (containing RBD and 51) show IFN-γ expression that is significantly higher compared to hAd5 null mice (FIG. 13a); splenocytes from these mice also expressed intracellular IFN-γ in response to the N peptide pool. Evaluation of simultaneous IFN-γ/TNF-α expression from CD8β+splenocytes (FIG. 13c) mirrored those for IFN-γ expression alone. These results indicate that both S and N activate CD8+ T cells.

CD4+activation by N: Although CD8+ cytotoxic T cells mediate killing of virus infected cells, CD4+ T cells are required for sustained cytotoxic T lymphocyte (CTL) activity. Thus, CD4+ T cells in the vaccinated animals was evaluated. In contrast to CD8β+splenocytes, only the N peptide pool stimulated CD4+splenocytes from hAd5 S-Fusion+N-ETSD-inoculated mice to express IFN-γ (FIG. 13b) or IFN-γ/TNF-α (FIG. 13d) at levels that were substantially higher than hAd5 Null control. The contribution by N of CD4+ T-cell responses is vital to an effective immune response to the candidate vaccine.