Fig. 5

RBD-PP has excellent in vivo safety. A Body weight and (B) body temperature throughout the immunization program using 50 μg of RBD-PP (n = 3). C ELISA of the levels of the serum inflammatory cytokines IFN-γ and IL-6 2 h and 24 h after subcutaneous injection of 50 µg of RBD-PP (n = 3). D Representative images of HE-stained mouse tissue sections after the immunization program was completed. E Analysis of metabolic biochemical markers in serum. 6 h and 7 days after the mice were subcutaneously injected with RBD-PP (50 μg), the serum levels of ALP, ALT, AST, and BUN were detected (n = 3). The gray area represents the fluctuation range of the normal level. Data are shown as the mean ± SD. Statistical significance was calculated via Student’s t test (C, E): ns no significance