VIRULENCE OF BORDETELLA-BRONCHISEPTICA - ROLE OF ADENYLATE CYCLASE-HEMOLYSIN

Bordetella bronchiseptica is a pathogen of laboratory, domestic, and w ild animals and sometimes of humans. In the present study some charact eristics of the virulence of B. bronchiseptica isolates of different o rigin were studied. All isolates had similar phenotypes, similar bacte riological characters, and synthesized adenylate cyclase-hemolysin, fi lamentous hemagglutinin and pertactin but not pertussis toxin. These i solates, however, differed in their ability to express dermonecrotic t oxin and to cause a lethal infection, but no correlation was found wit h the human or animal origin of the isolates. The fact that the most v irulent isolate did not express dermonecrotic toxin suggests that this toxin does not play an important role in the virulence of the bacteri a in the murine model. After infection with virulent B. bronchiseptica a very early synthesis and a persistence of anti-adenylate cyclase-he molysin and anti-filamentous hemagglutinin antibodies were observed in the sera of infected mice, suggesting a persistence of the bacteria o r of its antigens. B. bronchiseptica adenylate cyclase-hemolysin was p urified and was shown to be a major protective antigen against B. bron chiseptica infection. Furthermore, we showed that its immunological an d protective properties were different from that of B. pertussis adeny late cyclase-hemolysin, confirming that Bordetella species are immunol ogically different.