Analysis of the expression of outer-membrane proteins in Neisseria meningitidis in iron-replete and iron-deficient media.

A total of 103 Neisseria strains, including 42 carrier and 40 invasive N. meningitidis and 21 commensal species were studied. Outer-membrane proteins from carrier and invasive N. meningitidis showed similar molecular mass distributions (except in the range from 78 to 82 kDa in which 90% of the invasive but only 47.6% of the carrier strains expressed proteins), many strains showing neither class II (41 kDa) nor class III (38 kDa) proteins. When grown in iron-restricted conditions proteins were induced mainly in the ranges from 62 to 92 kDa with no significant differences between groups. Commensal species, both in normal and in iron-restricted conditions, showed outer-membrane protein patterns different from those of N. meningitidis in several molecular mass ranges. Cluster analysis based on expression of principal outer-membrane proteins allowed the differentiation of commensal species and N. meningitidis, although not that of the invasive and carrier groups within the latter.