Fig. 2.
Liposome presentation of HA trimers improves delivery to macrophages in vitro and outcomes of heterologous H3N2 influenza virus challenge following murine immunization. (A) Fluorescently labeled A/canine/Illinois/11613/2015 HA trimers were incubated with murine macrophages (1 μg/mL, 4 h, 37 °C) and subjected to flow cytometry to assess cellular uptake. Data show mean ± SD for n = 3 replicates. ICR mice were vaccinated intramuscularly with 100 ng A/canine/Illinois/11613/2015 (H3N2) HA trimers on days 0 and 21, prior to collecting sera and subjecting mice to challenge. (B) Day 42 Sera were assessed for HAI titer against heterologous A/Hong Kong/1/1968 (H3N2). Data show mean titer ± SD for n = 5 mice per group. Mice were challenged on day 60 with 2.5 × LD50 of mouse-adapted A/Hong Kong/1/1968 (H3N2) and euthanized 8 d postchallenge with analysis of (C) bodyweight, (D) viral titers in lung homogenates, and (E) white blood cell counts within lung tissue. Data show mean ± SEM for n = 8 mice per group. Statistical analysis was performed in B and C with one-way ANOVA and Dunnett’s comparison against alum and in D and E with one-way ANOVA with Tukey’s multiple comparisons. *P < 0.05, **P < 0.01.