Fig. 3: Subcutaneous Ad26.RSV.preF immunization induces durable humoral responses in neonatal mice.

Pups were subcutaneously immunized at Day 4–5 after birth, and boosted 3 or 6 weeks later with 10¹⁰ vp Ad26.RSV.preF in the immunization regimens displayed (n = 12 per group). Control groups received no immunization (indicated with - or sham), or FI-RSV (n = 6). a Prefusion (upper rows) or postfusion (middle rows) RSV F-binding antibody titers were determined by ELISA in serum at 3 weeks (left panels), 6 weeks (middle panels), and 9 weeks (left panels) after prime immunization. RSV CL57 VNA titers (lower row) in sera were determined 6 and 9 weeks after prime immunization. The lower limit of quantification of the assays are indicated with dashed lines, and horizontal bars represent the mean response per group. b Mice were followed for 25 weeks post-prime immunization, and RSV CL57 VNA titers were assayed in sera obtained 6, 9 (n = 12 per group), 13, 17, 21, and 25 (n = 6 per group) weeks after prime immunization. Data are presented as mean ± s.d. per group. ELISA titers are given as the log₁₀ value of relative potency, and VNA titers as the log₂ value of the IC90. NA not analyzed. Statistical analysis was performed with Wilcoxon Rank Sum test and Bonferroni correction, or Tobit regression and Tukey or Tukey–Kramer correction.