Cell-envelope proteins of Bordetella pertussis

Cell-envelope polypeptides of eight phase-I and five phase-IV strains of Bordetella pertussis were compared by SDS-polyacrylamide gel electrophoresis. All phase-I strains gave a strikingly similar but complex pattern of protein bands, which did not appear to vary with known differences in heat-labile agglutinogens. Phase-IV strains gave the same pattern as phase-I strains, except that one band was missing and another was either much reduced or absent. Envelopes from phase-I strains grown in Hornibrook medium rich in Mg-2+ ions to produce "antigenically-modulated" C-mode cells gave a pattern of bands indistinguishable from phase-IV strains. A phase-IV strain grown in the high-Mg-2+ medium gave the same pattern of bands as when grown in unmodified Hornibrook medium. We suggest that the two polypeptide bands that show changes may be responsible for one or more of the immunological or physiopathological activities that are lost during phase variation and antigenic modulation in B. pertussis.