Figure 7.

The SΔ19 Rep (R682G-S813Y) mutant stimulates robust neutralizing antibodies and Th1 immune response in hamsters. (A) Experimental design of a single dose vaccination with VSVΔG/G (control virus), SΔ19 Rep-R682G and SΔ19 Rep-R682G-S813Y in hamster (i.n.; 1×10⁶ pfu or ffu/hamster; n=4). The serum, spleen, and lung of the vaccinated hamsters were collected 2 weeks post-vaccination. Serum samples were subjected to anti-S_FL (B) and anti-S2_ECD (C) IgG ELISA, the RBD-hACE2 interaction competition assay (D), and the neutralization assay with the VSVΔG-based S pseudotyped virus (E) and SARS-CoV-2 virus (F). The anti-S_FL IgA expression in the lung homogenates was measured by ELISA (G). The isolated hamster splenocytes were stimulated with or without trimeric-S protein (5 μg/ml) for 72 hrs, and subjected to detect the TNF-α, IL-2, IL-6, IFN-γ and IL-12 mRNA expression by qRT-PCR (H). *P < 0.05; **P < 0.01.