Development of a pertussis component vaccine in Japan.

Antibodies against two physicochemically purified haemagglutinins (HAs) of Bordetella pertussis (filamentous HA and leucocytosis-promoting-factor HA) protect laboratory animals from pertussis. A vaccine containing these two HAs was prepared and tested in trials involving about 5000 children. Culture supernatant of Bordetella pertussis, phase I, was treated with ammonium sulphate, and a crude extract of the HAs was extracted from the precipitate by the use of concentrated sodium chloride. This crude extract was fractionated by sucrose density gradient centrifugation to obtain an HA preparation practically free of endotoxin. The HA preparation was treated with formalin to destroy its ability to induce leucocytosis and to cause histamine sensitisation. Aluminium hydroxide was added to the preparation as an adjuvant. The component vaccine is not only potent as judged by the mouse test but is also less than one-tenth as toxic as whole-cell vaccine as judged by leucocytosis promotion, histamine sensitisation, and endotoxicity tests. Field trials showed that component vaccine was as effective as and produced less side-effects than did conventional whole-cell vaccine. The vaccine has been used for mass immunisation in Japan since the autumn of 1981.