Fig. 3: Cell-mediated immune responses and virus-neutralization (VN) titers in mice immunized with different HAd vector formulations.

Seven-week-old BALB/c mice (3 males + 3 females per group) were intranasally (i.n.) mock-inoculated, or inoculated with 5 × 10⁷ plaque-forming units (PFU) of HAd-ΔE1E3, HAd-S, HAd-S/C5, HAd-M, HAd-M/C5, HAd-N, HAd-N/C5, HAd-S + HAd-M, HAd-S/C5 + HAd-M/C5, HAd-S + HAd-N, HAd-S/C5 + HAd-N/C5, HAd-M + HAd-N, HAd-M/C5 + HAd-N/C5, HAd-S + HAd-M + HAd-N, or HAd-S/C5 + HAd-M/C5 + HAd-N/C5 twice at four weeks interval. Four weeks post-booster inoculation, splenocytes (A–C) and lung mononuclear cells (D–F) were collected and analyzed for S- (A, D), N- (B, E), or M-specific (C, F) T cell-mediated immune responses by ELISpot assay. The numbers of IFN-γ-secreting cells per 10⁶ splenocytes (A–C) or 10⁵ lung mononuclear cells (D–F) are presented. Statistical analysis was performed using U-test Mann-Whitney for non-parametric data. Significance levels were set at *p < 0.05; and **p < 0.01. VN titers against SARS-CoV-2 variants in sera of mice immunized with different HAd vector formulations. Four weeks post-booster inoculation, the serum samples were collected and used to study the development of VN titers against SARS-CoV-2 variants: hCoV-19/USA-WA1/2020 (Wuhan) (G), hCoV-19/USA/PHC658/2021 (B.1.617.2, Delta) (H), or hCoV-19/USA/GR484A/2021 (B.1.1.529, Omicron) (I) by VN assay.