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The safety and immunogenicity of an acellular pertussis vaccine containing the genetically detoxified pertussis toxin PT-9K/129G, filamentous hemagglutinin, and pertactin, together with diphtheria and tetanus toxoids, were compared with those of a whole-cell pertussis component-diphtheria-tetanus vaccine. Four hundred eighty infants were enrolled into this prospective, multicenter, double-blind study. Each infant was randomly given three doses of one of the two vaccines at 2, 4, and 6 months of age. Both local and systemic adverse reactions, reported within 48 hours and 7 days of each injection, were less frequent after the acellular vaccine than after the whole-cell vaccine. The enzyme-linked immunosorbent assay titers to pertussis toxin, filamentous hemagglutinin, and pertactin, as well as the pertussis toxin-neutralizing titer measured by the Chinese hamster ovary cell assay, were significantly higher after the acellular vaccine was given. Both vaccines induced adequate levels of anti-diphtheria and anti-tetanus antibodies. We conclude that the recombinant acellular pertussis vaccine produces fewer reactions than the whole-cell vaccine and provides a high antibody response against the antigens of Bordetella pertussis involved in bacterial adhesion and systemic toxic effects.

We studied the immunogenicity of an acellular pertussis vaccine composed of genetically detoxified pertussis toxin (PT-9K/129G), filamentous haemagglutinin, and a 69-kilodalton protein, pertactin, in 30 children aged 12 to 24 months and in 80 infants aged 2 to 4 months. A significant increase of the neutralizing titer and of the titers against pertussis toxin, filamentous hemagglutinin, and pertactin, as determined by enzyme-linked immunosorbent assay, was achieved after three doses of vaccine in all the children; a significant increase of these antibody titers was obtained in 100%, 96.1%, 93.5%, and 98.7% of the infants, respectively.

To determine whether a nontoxic derivative of pertussis toxin obtained by recombinant DNA technology, PT-9K/129G, is a good candidate for a new pertussis vaccine, we examined the safety and the immunogenicity in children of a vaccine containing 15 micrograms of PT-9K/129G protein and 0.5 mg of aluminum hydroxide per dose. Fifty-three children 12 to 24 months of age and 21 infants aged 2 to 4 months were injected with two and three doses, respectively. The vaccine did not induce significant local or systemic reactions and elicited an increase of antibody titer in more than 98% of the children. The geometric mean of the toxin-neutralizing titers increased after each dose and was 85 units in children given two doses and 196 units in those given three doses. Two children who had detectable antibody levels before the first immunization had a high response (greater than 320 units) to the first vaccine dose. The findings suggest that PT-9K/129G is a promising antigen to be included in the development of acellular pertussis vaccines.