Protection against intranasal infection of mice with Bordetella pertussis.

Mice have been infected by intranasal instillation of Bordetella pertussis and the infection monitored by determining numbers of bacteria isolated from the lungs. Outer membrane proteins, filamentous hemagglutinin, toxoided-lymphocytosis promoting factor and agglutinogens (fimbriae) actively protect mice against intranasal infection and antibodies of the antigens neutralize infectivity. The neutralization of infection by agglutinins is serospecific. In general, antigens that actively protect mice against intracerebral infections also protect against intranasal infections but some antigens, such as filamentous hemagglutinin and agglutinogens, protect only against intranasal infections. The intranasal protective potency of antigens can be enhanced by including low levels of active lymphocytosis promoting factor in the preparations. The relevance of the intranasal test to the potency testing of pertussis vaccines is discussed.