FIG 5.

Disruption of nasal bacteria or intranasal administration of cultured oral bacteria induces the HA-specific antibody responses in a MyD88-dependent manner. (A to D) WT and MyD88-deficient mice were immunized intranasally with a quadrivalent HA vaccine with or without cultured oral bacteria from a healthy volunteer (A and B) or lysozyme (C and D) twice in a 3-week interval. Two weeks later, the nasal washes and sera were collected and the HA-specific nasal IgA and serum IgG titers were determined by ELISA. (E and F) MyD88-deficient mice were inoculated intranasally with an antibiotic cocktail (Abx) for 5 consecutive days. Two days later, mice were intranasally infected with 1,000 PFU of A/PR8 virus. The nasal washes and sera were collected at 4 weeks p.i., and the virus-specific nasal IgA and serum IgG titers were determined by ELISA. Open circles indicate values for individual mice. The data are from two independent experiments (mean ± SEM). ***, P < 0.001; n.s., not significant (one-way ANOVA and Tukey’s test).