Fig. 1

Long-term memory immunity induced by inactivated EV-A71 or EV-D68 mucosal vaccines in mice. Mice were intranasally immunized with PBS, formalin-inactivated EV-A71 (2.5 μg/mouse), or EV-D68 (2.5 μg/mouse) thrice at 3-week intervals. a Immunization schedules for the EV-A71 mucosal vaccine. Serum and faecal samples were collected from immunized mice at weeks 8, 11, 14, 22, and 24. The levels of EV-A71-specific IgG and IgA in the serum (b, c) and feces (d, e) were measured using ELISA. f Neutralization titre against EV-A71 C2 infection in the serum of immunized mice. g Immunization schedules for the EV-D68 mucosal vaccine. Serum, feces, and saliva samples were collected from immunized mice at weeks 8, 11, 14, 25, and 27. The levels of EV-D68-specific IgG and IgA in the serum (h, i), feces (j, k), and saliva (l, m) were measured using ELISA. n Neutralization titre against EV-D68 1788 infection in the serum of immunized mice. *p < 0.05; **p < 0.01; ***p < 0.001