Severe histopathology is associated with formalin-inactivated RSV (FI-RSV) vaccination, but not NE-RSV.

<p>Mice were vaccinated with NE-RSV or FI-RSV, as described, and challenged with live RSV. (A) Representative lung histology (Periodic Acid Schiff's, PAS) from unvaccinated control, NE-RSV vaccinated, and FI-RSV vaccinated mice at day 8 post-infection. In (B), the absolute number of eosinophils (Eos), neutrophils (NEUT), small mononuclear cells (MONO), and macrophages (MAC) in the BALs of unvaccinated, NE-RSV vaccinated, and FI-RSV vaccinated mice at day 8 post-infection were determined via hemocytometer and differential staining. * = p<0.05, as assessed by ANOVA followed by Tukey's multiple comparison test. All other pairwise comparisons were not statistically significant.