Protective activities of the filamentous hemagglutinin and the lymphocytosis-promoting factor of Bordetella pertussis in mice.

Protective activities of the filamentous hemagglutinin (FHA) and the lymphocytosis-promoting factor (LPF) of Bordetella pertussis were compared by active and passive protection tests with intracerebral or respiratory challenge in mice. Mice immunized twice by intraperitoneal injection of 8 micrograms of FHA or glutaraldehyde-inactivated LPF were protected after aerosol challenge. One intraperitoneal injection of inactivated LPF also protected mice from intracerebral challenge; the dose protecting 50% of the mice was 8.5 micrograms. However, one intraperitoneal injection of 48 micrograms of FHA or two weekly intraperitoneal injections of 20 micrograms did not protect mice from death after intracerebral challenge. Injection of affinity-purified antibody to LPF from mouse hybridomas or from goats gave a dose-dependent protection against aerosol challenge. The smallest dose giving protection was 80-90 micrograms. Polyclonal or monoclonal antibody to FHA at doses of 1,440 micrograms or 360 micrograms, respectively, gave very little protection from disease after respiratory challenge. These data indicate that active immunization of mice followed by respiratory challenge with B. pertussis is a useful model to identify protective antigens.