Biologic and protective properties of the 69-kDa outer membrane protein of Bordetella pertussis: a novel formulation for an acellular pertussis vaccine.

A combination of the 69-kDa outer membrane protein and filamentous hemagglutinin (FHA), both isolated from lymphocytosis promoting factor (LPF; pertussis toxin) minus mutants of Bordetella pertussis, is protective in the mouse intracerebral challenge potency (Kendrick) test. A combination of the same 69-kDa protein and LPF is approximately 15 times less effective. These data suggest that, surprisingly, the 69-kDa protein in tandem with FHA is the most relevant combination for mouse protection; consequently such a combination may be a more suitable acellular pertussis vaccine candidate than the LPF/FHA combinations, which have never been satisfactorily protective in the mouse test. Preparation of samples of the 69-kDa protein of acceptable protective quality remains difficult. Attempts were made to screen the most suitable batches of the preparations by exploiting some recently discovered properties of the 69-kDa protein: the characteristic chromatofocusing pattern of the protein, the affinity for lymphocytes, and the ability to bind to nicotinamide adenine dinucleotide. None of these tests was able to replace the mouse intracerebral challenge potency test for final quality assessment.