FIG 8.
Determination of HA-specific antibodies and neutralizing antibodies. The HA-specific serum IgG titer (a) and the fecal (b) and BALF (c) IgA antibody titers were detected by indirect ELISA. Purified HA protein was used as the plate-coating antigen. Endpoint titers (log2) were calculated in accordance with the dilution of the serum, feces, and BALF by indirect ELISA. (d) Neutralizing antibody levels were detected in 10-day-old embryonated SPF eggs. Neutralizing antibody titers (log10) were calculated by the Reed and Muench method (39). The statistical significance was calculated using one-way ANOVA (**, P < 0.01; ***, P < 0.001).