Biological and protective activities of outer membrane proteins from Bordetella

In this work the biological properties and the capability of the outer membrane proteins (OMPs) from different strains of Bordetella to induce protection against challenge with B. pertussis 18323 were examined. The OMPs from each strain were isolated using Schnaitmann's method. Two OMPs (30 and 32 kDa) were found to be specific for the vaccine strains of B. pertussis and were absent in the OMPs preparation from both B. parapertussis and B. bronchiseptica. When the OMPs from the vaccine strains of B. pertussis were assayed in the mouse intracerebral protection test, they were found to be highly protective (75%-88%) against a challenge with 250 50% lethal doses (LD50) of B. pertussis 18323. However, no correlation was observed between the protective activity and the lymphocytosis-promoting factor (LPF) content of different preparations. Moreover, neither LPF activity or histamine-sensitizing activity (HSA) were found in any of the OMPs assayed. Our results show that OMPs from B. pertussis vaccine strains play a key role in the induction of protective immunity against B. pertussis 18323 in mice, making them excellent candidates to be used in further studies for the development of a pertussis vaccine for humans.