Fig. 3: Immunogenicity of S-Trimer in mice.
From: S-Trimer, a COVID-19 subunit vaccine candidate, induces protective immunity in nonhuman primates
BALB/c mice (n = 7–8/group) were immunized with various doses of S-Trimer that was non-adjuvanted or adjuvanted with 25 µL AS03, 10 µg CpG 1018, or 10 µg CpG 1018 plus 50 µg alum twice on Day 0 and Day 21. The humoral immune responses on Day 35 were analyzed and compared with a human convalescent sera (HCS) panel (n = 41), based on a S-Trimer binding antibody ELISA titers, n = 7–8, b ACE2-competitive ELISA titers, n = 7–8, and c SARS-CoV-2 pseudovirus neutralization titers, n = 7–8. After necropsy, splenocytes were harvested from mice and stimulated with S-Trimer antigen, followed by d detection of Th1 (IL-2, IFNγ) and Th2 (IL-4, IL-5) cytokines by ELISpot. ELISpot data shown represents pooled data across S-Trimer doses (S-Trimer group, n = 6; S-Trimer+AS03 group, n = 9; S-Trimer+CpG group, n = 9; S-Trimer+alum+CpG group, n = 18; and Blank mouse group, n = 3–4). Points represent individual animals or humans; horizontal lines indicate geometric mean titers (GMT) for antibody assays and mean values for ELISpot assay for each group ±SEM. For statistical analysis of antibody titers, all comparisons were made against HCS sera using Kruskal–Wallis ANOVA with Dunn’s multiple comparisons tests. In the ELISpot assays, for all cytokines, the comparisons were compared to blank mouse control with Two-tailed Mann–Whitney tests. P values < 0.05 were considered significant.
