Fig. 1

Humoral and cellular immune responses in ARCoV-immunized cynomolgus macaques. Cynomolgus macaques were immunized i.m. with 50 μg (n = 3) or 200 μg (n = 4) of ARCoV or a Placebo (n = 3) and boosted with the same dose on day 14 after first vaccination. a Schematic diagram of vaccination, sampling, and viral challenge in cynomolgus macaques. b SARS-CoV-2 RBD-specific IgG antibody titers of the immunized animals were determined by ELISA. c, d The NT₅₀ and PRNT₅₀ titers of the immunized animals were detected using VSV-based pseudovirus and live SARS-CoV-2, respectively. The dashed lines indicate the detection limit of the assay. Data are shown as mean with floating bars (min to max). Symbols represent individual animals. Statistical significance was calculated using a Student’s t test (n.s. not significant; *p < 0.05, **p < 0.01, ****p < 0.0001). e, f Serum cross-neutralization assays against SARS-CoV-2 epidemic strains and variants of concern in animals immunized with 200 μg of ARCoV. PRNT₅₀ were performed using animal sera collected on day 28 after the first vaccination. The data were analyzed by a Paired t-test. g, h ELISpot assays for IFN-γ and IL-4 in PBMCs of the ARCoV-immunized cynomolgus macaques. Data are shown as mean ± SEM. Significance was calculated using a Student’s t test (*p < 0.05, ****p < 0.0001)