Inter-strain Homology of Pilin Gene Sequences in Neisseria meningitidis Isolates That Express Markedly Different Antigenic Pilus Types

Abstract

Neisseria meningitidis isolates examined in this study elaborated one of two pilus types that were antigenically markedly different. Each pilus type reacted either with S M l , a monoclonal antibody that recognizes an epitope common to all gonococcal pili, or with a polyclonal antiserum raised against meningococcal pili that did not react with SM 1, but not both. Total genomic DNA from all N. meningitidis isolates analysed, irrespective of pilus type, contained at least one region with extensive homology to a gonococcal pilE probe. Different N . meningitidis strains possessed one of several configurations of genomic pilE-homologous segments. Chromosomal rearrangement of pilE-homologous sequences was associated with P+ to P-pilus phase transition in the strains examined. The arrangement ofpilE-homologous segments in total genomic DNA from N. meningitidis isolated from the blood and cerebro-spinal fluid of the same patient was apparently identical.

Shared themes of antigenic variation and virulence in bacterial, protozoal, and fungal infections.

“…Mature pili mediate adherence to a number of different eukaryotic cell types and affect interactions with epithelia, endothelia, and phagocytes (80,177). Analysis of different pilin sequences has shown that they comprise constant, semivariable, and hypervariable regions (52,127), allowing them to be grouped into two general molecular categories, class I and class II. In different clinical isolates, the hypervariable region accounts for most of the variations in size, isoelectric point, and amino acid composition of the pilins (89,128) and is an important determinant of the antigenicity of the bacteria and their binding affinities to human cells (127,177).…”

“…Analysis of different pilin sequences has shown that they comprise constant, semivariable, and hypervariable regions (52,127), allowing them to be grouped into two general molecular categories, class I and class II. In different clinical isolates, the hypervariable region accounts for most of the variations in size, isoelectric point, and amino acid composition of the pilins (89,128) and is an important determinant of the antigenicity of the bacteria and their binding affinities to human cells (127,177). Antigenic variation of pilins may involve posttranslational modifications of the subunits as well.…”

The Biology of Neisseria Adhesins

“…Antigenic variation of Tfp expression, which results from both inter- and intra-genomically non-reciprocal DNA recombination between pilS (silent) genes and pilE genes [41,47,48,49,50] is known to contribute to evasion mechanisms employed by pathogenic Neisseria [51]. Furthermore, pili from different infection sites of the same patient with meningococcal disease can be antigenically diverse [52].…”