Figure 3.

Lung samples (n = 3) were collected from challenge-infected mice, and antibody inductions were evaluated. (A–C) IgG, IgG1, and IgG2a responses of mice infected with 10 LD₅₀ influenza virus were determined by ELISA. (D–F) Antibody levels in the lungs of 2 LD₅₀ virus-infected mice were assessed. Data are presented as median ± SD (* p < 0.05, ** p < 0.01) and are representative of the two independent immunization studies conducted on mice. Abbreviations: Naïve + cha—unimmunized infection control; HA VLPs—virus-like particles (VLPs) expressing hemagglutinin (HA) antigen only; NA VLPs—VLPs expressing neuraminidase (NA) antigen only; HANA VLPs—VLPs expressing both HA and NA antigens; M1 VLPs—VLPs expressing only M1 antigen.