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. 2014 Mar 25;22(7):1364–1374. doi: 10.1038/mt.2014.33

Figure 4.

Figure 4

Mucosal antibody responses, IL-6 in BALF, and lung viral titers after boost immunization upon heterosubtypic challenge. Levels of IgG and IgA antibodies were determined from BALF at day 4 postchallenge (N = 4) from the mice after boost vaccination. (a) M2e-specific IgG antibody response. (b) M2e-specific IgA antibody response. IgG or IgA antibody responses were determined by ELISA using human type M2e peptide as a coating antigen (4 µg/ml). Levels of IL-6 cytokine and lung viral titers were determined at day 4 postchallenge (N = 4). (c) IL-6 cytokine in BALF. IL-6 was determined by a cytokine ELISA (N = 4). (d) Lung viral titers. Lung viral titers were determined by an egg inoculation assay day 4 postchallenge (N = 4). P value indicates significant difference between split+M2e5x and split vaccinated or naive groups. Data represent mean ± SEM. BALF, bronchoalveolar lavage fluid; ELISA, enzyme-linked immunosorbent assay; IL, interleukin; M2e, M2 ectodomain; VLP, virus-like particles.