Structure and biological properties of solubilized envelope proteins of Bordetella pertussis

The structure and biological properties of solubilized envelope proteins of Bordetella pertussis have been examined. Several envelope proteins were found to be specific for phase I strains of B. pertussis and could be isolated by selective detergent extraction. These proteins had molecular weights of 90,000, 86,000, 81,000, 33,000, 31,000, and 30,000 and were reduced or absent in envelope preparations from Bordetella bronchiseptica, Bordetella parapertussis, or phase IV strains of B. pertussis. When the envelope preparations from phase I B. pertussis were assayed in the mouse intracerebral protection test they were found to be highly protective, and there was a strong correlation between the protective potency and the lymphocytosis-promoting factor (LPF) content of different preparations. Treatment with glutaraldehyde reduced the LPF activity, toxicity, and protective potency of the envelope extracts. Similarly affinity chromatography of envelope proteins on columns of haptoglobin coupled to Sepharose 4B reduced both the LPF content and the protective potency. The addition of a small amount of purified LPF to the haptoglobin-treated proteins restored the protective potency. The LPF by itself was nonprotective, indicating a potentiating role of LPF in the mouse intracerebral challenge test.