Fig 7. NAb induction of pre-F and post-F formulations in aged seropositive mice.

12 months old mice were i.n. immunized with RSV A2 (10⁶ PFU) at day 0 and RSV B (10⁵ PFU) at day 60. Aged seropositive mice were then immunized i.m. at day 176 (18 months old) with buffer alone, post-F or pre-F (0.3 μg) +/- GLA-SE (2.5 μg/2%) adjuvant. (A) Bleeds were collected at day 50, 120, and 174 to assess the levels of RSV A2 neutralizing antibodies in seropositive animals prior to immunization (baseline). Data is presented as the log₂ dilution of serum that provides 50% reduction in viral entry with a LLOD of 4 indicated by a dashed line. (B) 14 days post immunization, RSV A2 neutralization titers were evaluated. Group means ± SD of individual mice are shown. For statistical analyses, multiplicity adjusted ANOVA test was performed against baseline as a control group, followed by pairwise testing of post-F versus pre-F, * for P<0.05.