Protection and humoral immune responses against Bordetella pertussis infection in mice immunized with acellular or cellular pertussis immunogens

In the present study, protection against Bordetella pertussis infection and humoral immunological responses in mice has been assessed upon immunizatio n with custom-made acellular pertussis vaccines (ACVs) and whole-cell pertu ssis vaccine (WCV). Mice were immunized, next intranasally infected with B. pertussis and during 14 days the number of bacteria in the trachea and lun gs and the level of serum antibodies were determined. ACV contained five im munogens, filamentous hemagglutinin, pertactin, fimbriae serotypes 2 and 3, and chemically detoxified pertussis toxin (PMC-5), or three immunogens, fi lamentous hemagglutinin, pertactin, and genetically detoxified (BC-3) or ch emically detoxified pertussis toxin (SKB-3). Immunization with a high or lo w dose of ACV or WCV resulted in significant protection against B. pertussi s, with differences in the degree of protection between the vaccines. The l owest protection was found with a low dose of SKB-3 and WCV. The pattern of cytokine production by spleen cells of immunized, non-infected, mice indic ated that T-helper 1 cells are activated by vaccination with WCV, and T-hel per 1 and T-helper 2 cells are involved in the immune response upon vaccina tion with ACVs. Each vaccine stimulated the production of IgG, but not IgA, antibodies. In mice immunized with ACV, elimination of B. pertussis from t rachea and lungs correlated significantly with the titre of IgG1, but not I gG2a, antibodies. (C) 2000 Elsevier Science Ltd. All rights reserved.