Fig. 4.

Protection of mRNA-A-LNP and mRNA-B-LNP against VACV Challenge in Mice. a, b Thirty days after initial immunization, mice (n = 5) were s.c. challenged with VACV (4 × 10⁵ TCID₅₀). The viral load of mice was measured by bioluminescence imaging, and the bioluminescence signal of mice was measured 24 h after the challenge. c, d In vitro serum protection. Serum (13 μl) and virus (4 × 10³ TCID₅₀) were mixed for 1 h before the i.v. and i.p. challenges of the 4-week-old nude mice (n = 3). Bioluminescent signal measurements were taken 6 h after the viral challenge. e, f In vivo serum protection. Serum (50 μl) was first injected intravenously into the 4-week-old nude mice (n = 3), followed 1 h later by s.c. challenge with VACV (2.5 × 10⁵ TCID₅₀). Bioluminescent signal measurements were taken 24 h after the viral challenge. Data are shown as mean ± SEM. Significance was calculated using one-way ANOVA with multiple comparison tests (**p < 0.01, ****p < 0.0001)