Structural and antigenic analysis of meningococcal piliation.

Pilin with an Mr of 16,500 was purified to homogeneity from Neisseria meningitidis SP3428. Procedures which provided useful separation during purification included high-pressure liquid chromatography with a TSK size exclusion column, Sephacryl S-200 column chromatography, ion-exchange chromatography with SP-Sephadex, and preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The amino acid composition of this pilin was similar to that previously reported for this species. The sequence of N-terminal 51 amino acids was also determined. The protein lacked a modified phenylalanine at the amino terminus and displayed six residues which were different from Neisseria gonorrhoeae in that region of the molecule determined to be the lectin-binding domain. Monoclonal antibody raised to this pilin was employed, along with a monoclonal antibody to an epitope common to all gonococcal pilins, to analyze the intra- and interstrain heterogeneity of meningococcal piliation. The results indicate that N. meningitidis displays considerable intra- and interstrain heterogeneity with respect to both pilus subunit size and antigenicity. The Mr of subunits ranged from 13,000 to 20,000.