Fig. 1.

Immune responses to the RSV F nanoparticle vaccine. Cotton rats (n = 8) were immunized on day 0 and 28 with FI-RSV, RSV-A2, or RSV-F nanoparticle vaccine with and without AdjuPhos. An additional group received palivizumab 15 mg/kg intramuscularly on day 48, one day prior to challenge. A placebo group served as a negative control. Sera were obtained from all the groups on day 49, prior to challenge. Panel A. RSV F IgG responses as determined by ELISA; expressed as log₁₀ of the GMT with 95% CI. Panel B. Palivizumab competing antibody (PCA) were reported as the μg/ml (log₂) antibodies required for 50% inhibition of binding of palivizumab to RSV F. Panel C. Neutralizing antibody titers against RSV-A2 providing 60% inhibition of CPE (log₂). GMT for each group is shown with the 95% CI. *p values <0.01; NS: not significant compared with RSV-infection group by two-tailed Student t-test; LOD is the lower limit of detection.