Inferior immunogenicity and efficacy of respiratory syncytial virus fusion protein-based subunit vaccine candidates in aged versus young mice
Fig 2
Lung T cell profile after RSV challenge in young and aged seronegative mice immunized with post-RSV F formulations.
Young (7 weeks old) and aged (18 months old) BALB/c mice (n = 4 to 7 per group) were immunized i.m. at day 0 and day 21 with buffer alone, post-F (0.3 μg) +/- GLA-SE (2.5 μg/2%) adjuvant. A control group for natural infection was immunized i.n. with live RSV (106 PFU) at day 0. At day 35, animals were challenged i.n. with 106 PFU of wt RSV A2. 4 days post-challenge (day 39), lung cells were isolated and stimulated with RSV F peptide pool to evaluate intracellular cytokine expression by flow cytometry. Cells were surface stained for CD3 and CD8, intracellularly stained for IFNγ, TNFα, and IL-2, and analyzed on an LSR II for the frequency of responding (A) CD4+ and (B) CD8+ T cells. (C) The percentage of F85-93-pentamer+ CD8 T cells was determined by flow cytometry. (D) The percentage of lung eosinophils was determined by flow cytometry. For (C) and (D), the mean of individual values +/- SD is shown. For statistical analyses, aged and young mice were compared. *, P<0.05.