Skip to main content
. 2023 Jul 3;31(8):2360–2375. doi: 10.1016/j.ymthe.2023.06.017

Figure 4.

Figure 4

Intramuscular injection of repRNA/LION induces a comparable binding antibody response to repRNA/LNP despite lacking systemic innate responses in mice

(A) C57BL/6 mice received an intraperitoneal injection of anti-IFNAR1 Ab (2 mg) or were left untreated. Twenty-four hours later, mice were i.m. injected with 10 μg of repRNA encoding firefly luciferase (Fluc) delivered by LION and LNP. At 24 h after the i.m. injection, luciferase expression was analyzed in vivo by IVIS. The total flux data over the course of in vivo transfection of repRNA are shown as means ± SD (data are the pool of two independent experiments; n = 4). Statistical comparison of mean values between groups at each time point was performed by ordinary two-way ANOVA and Tukey’s multiple comparisons test. The complete list of the results of the statistical test is included in Table S3. (B) The experimental design for analyzing the antigen-specific binding Ab response to SARS-CoV-2 Spike protein. C57BL/6 mice received i.m. injection of repRNA encoding SARS-CoV-2 Spike protein (1 or 10 μg) formulated with LION or LNP at days 0 and 35 (n = 5). The left panel shows the regimen for a 1-μg dose. The right panel shows the regimen for a 10-μg dose. For the 10-μg dose regimen, the mice also received an intraperitoneal injection of isotype IgG or α-IFNAR1 (2 mg) 1 day before immunization. (C) At 14 h, serum IFN-α2 levels were measured by ELISA. Statistical comparison of mean values among groups was performed by multiple unpaired t tests between values in the LION group vs. values in the LNP group at each time point. (D and E) Anti-SARS-CoV-2/Spike protein binding Ab response at day 28 (post-prime) (D) and day 49 (post-boost) (E) determined by ELISA. Statistical comparison of mean values among groups was performed by ordinary two-way ANOVA and Tukey’s multiple comparisons test between the values in each group. Unless otherwise noted, only statistically significant results are shown as asterisks: ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.001, ∗∗∗∗p < 0.0001; ns, not significant.