Figure 6.

RSV-neutralizing antibodies induced by immunization with VSV-GP-F_syn are long-lasting. BALB/c mice (n = 5) were immunized in weeks 0 and 4 intramuscularly with 10⁷ TCID₅₀ VSV-GP-F_syn, VSV-GP or 10⁶ FI-RSV, intranasally with 10⁷ VSV-GP-F_syn or first intramuscularly followed by intranasally with 10⁷ VSV-GP-F_syn. One group received a single intranasal immunization with 10⁷ VSV-GP-F_syn in week 4. (A) EDTA plasma was collected 20 weeks after boost and analyzed for the titer of RSV neutralizing antibodies; (B) in week 20 after boost, mice were infected with 10⁶ PFU of replication competent RSV. On day 5 after infection, mice were sacrificed, and lungs were analyzed for the titer of RSV by qPCR. Statistical significances were determined in a one-way analysis of variance (Kruskal–Wallis test) followed by Dunn’s Multiple Comparison Test (*, p ≤ 0.05; **, p ≤ 0.01). Geometric mean is indicated; the dotted lines indicate the detection limits of the assays.