FIG 3.

Intranasal administration of HA-CoPoP/PHAD induces IgA and IgG in the respiratory tract. Mice were vaccinated with 100 ng of HA trimers from A/Ca/Illinois/11613/2015 H3N2 bound to CoPoP/PHAD liposomes via the indicated route (IN, intranasal; IM, intramuscular; No HA, untreated). Following primary vaccination on day 0 and booster vaccination on day 14, serum, nasal lavage, and lung tissue were collected. IgA antibody titers measured in blood serum, nasal lavage fluid, and homogenized lung tissues (A to C) were compared against IgG antibody titers in the same tissues (D to F). Error bars indicate standard deviation. Statistical analysis was performed with one-way ANOVA with Tukey’s multiple comparisons. *, P < 0.05; **, P < 0.01; ***, P < 0.005; and ****, P < 0.001.