Fig. 4: Trivalent circRNA vaccine induced a balanced immune response against N1, N2, and influenza B NA.
a Trivalent circRNA vaccine immunization and challenge regimen. Mice received a prime-boost immunization program with 4 weeks intervals, 4 weeks after boost vaccination mice were challenged with 5 × LD50 or 1 × LD50 influenza virus. Body weight and survival rate were monitored for 14 days. Some mice were euthanized, and lungs were collected at 4 dpi. A blank LNP group was used as a control. The figure was created by the author using Adobe Illustrator 2020. ELISA was used to measure the binding antibody titers against Mich15 (b), SL32 (c), and BCOL17 (d) in the serum samples from the trivalent vaccine group. e The binding breadth of trivalent vaccine immune sera after boost vaccination. The radar diagram shows each group’s geometric mean titer (GMT) (n = 5). The abbreviation of the virus strain was the same as in Fig. S1. NAI titer of trivalent immune sera. NA inhibition antibody titers against Mich15 (f), SL32 (g), and BCOL17 (h) were detected by ELLA. Neutralization titer of boost immune sera for trivalent vaccine. Microneutralization titers against CA09 (i), SL32 (j), and BCOL17 (k) virus were detected by microneutralization assay. Data are presented as the mean ± SD (n = 5), and each symbol represents one animal. The dashed lines correspond to the lowest initial dilution. Statistical significance was performed by One-way ANOVA; Unpaired Student’s t tests were used to compare antibody titers between prime and boost sera within the same dosage group of mice; *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001. ns, not significant.
