Mucosal immunization with filamentous hemagglutinin protects against Bordetella pertussis respiratory infection.

Mucosal immunization of mice with purified Bordetella pertussis filamentous hemagglutinin (FHA), by either the respiratory or the gut route, was found to protect against B. pertussis infection of the trachea and lungs. Intranasal immunization of BALB/c and (C57BL/6 x C3H/HeN)F1 adult female mice with FHA prior to B. pertussis aerosol challenge resulted in a 2 to 3 log reduction in number of bacteria recovered from the lungs and the tracheas of immunized mice in comparison to unimmunized controls. Intraduodenal immunization of adult mice with FHA before infection also resulted in approximately a 2 log reduction in the recovery of bacteria from the lungs and the tracheas of immunized mice in comparison to unimmunized controls. Immunoglobulin A and immunoglobulin G anti-FHA were both detected in bronchoalveolar lavage fluids of mucosally immunized mice. Limiting dilution analysis revealed a 60-fold increase in the frequency of FHA-specific B cells isolated from the lungs of mice immunized intranasally with FHA in comparison to unimmunized control mice. These data suggest that both gut and respiratory mucosal immunization with a major adhesin of B. pertussis generates a specific immune response in the respiratory tract that may serve as one means of mitigating subsequent B. pertussis respiratory infection.