Figure 9. UB-612–induced long-lasting, robust Th1-predominant cell response measured by IFN-γ and IL-4 ELISpot after restimulation of PBMCs with designer peptide antigens.
In the 196-day phase I trial with 2 UB-612 doses on days 0 and 28, vaccine-induced T cell responses were measured by IFN-γ ELISpot with PBMCs from young adults (20–55 years old) in (A) 10, (B) 30, or (C) 100 μg dose group (n = 20 each). In the phase II trial study, participants (younger adults, 18–65 years old) received 2 doses of UB-612 at 100 μg (n = 88) or saline placebo (n = 12), and T cell responses in PBMCs of vaccinees on day 57 restimulated with designer antigen protein/peptides were measured by (D) IFN-γ and (E) IL-4 ELISpot. Shown are spot-forming units (SFU) per 1 × 106 PBMCs producing IFN-γ and IL-4 after stimulation with S1-RBD plus Th/CTL peptide pool, Th/CTL peptide pool, or SARS-CoV-2 T peptides (Th/CTL peptide pool without UBITh1a). Statistical analysis was performed with the use of the 2-sample t test. ****P < 0.0001.