Figure 2.

Humoral immune responses after RABV mRNA vaccination. (A) Schematic of the immunization, rabies virus challenge, and sampling strategy. Six- to eight-week-old female BALB/c mice were immunized intramuscularly twice at day 0 and 14 with RABV G, tG-MTQ, preG, VLP, and VLP/N mRNA vaccine, respectively, followed by virus challenge and tissue sample collection. (B to E) RABV-specific IgG and IgG antibody isotype (IgG1, IgG2a, and IgG2b) titres were quantified by ELISA, respectively, from serum samples collected on day 28 (n = 6). (F) The ratio of IgG2a/IgG1 and IgG2b/IgG1 were determined from the absorbance values of 100-fold diluted serum at day 28 measured at 450 nm. (G and H) Neutralizing antibody (Nab) titres of serum collected at day 14 and 28 were analyzed by Rapid Fluorescent Focus Inhibition Test (RFFIT) assay (n = 6). The dashed line at 0.5 IU/mL represents a protective titre for RABV Nab titre. (I) Spearman correlation of (B) RABV-specific IgG titres and (H) Nab titres. (J) Kinetic of Nab in mice immunized with RABV mRNA vaccines or inactivated vaccines after a single vaccination (n = 3). * P < 0.05; ** P < 0.01; *** P < 0.001; **** P < 0.0001; ns, no significant difference. Data represent mean ± SEM.