Mouse-protecting and histamine-sensitizing activities of pertussigen and fimbrial hemagglutinin from Bordetella pertussis.

We compared the protective activities of fimbrial hemagglutinin (FHA) and pertussigen and their respective antibodies in mice infected intracerebrally with Bordetella pertussis. We found that mice were protected by a 1.7-microgram/mouse dose of pertussigen which was free of detectable FHA and was detoxified by treatment with glutaraldehyde. A pertussigen preparation made from cells grown in shake cultures that did not contain demonstrable FHA protected mice at a dose of 1.4 microgram/mouse. FHA at a dose of 10 microgram/mouse protected mice from intracerebral infection, but it also sensitized mice to histamine at a dose of 2 micrograms/mouse, which indicated that it was contaminated with pertussigen. When FHA was obtained free of demonstrable pertussigen, it failed to sensitize mice to histamine at a dose of 30 micrograms/mouse and to protect mice from infection at a dose of 12 micrograms/mouse (largest doses tested). Passive protection tests with antisera known to contain antibodies to pertussigen protected mice from intracerebral infection, whereas sera lacking anti-pertussigen antibodies but containing high concentrations of anti-FHA antibodies did not protect mice. The most important antigen for the immunization of mice against intracerebral infection with B. pertussis appears to be pertussigen.