Description and Nomenclature ofNeisseria meningitidisCapsule Locus

Abstract

Pathogenic Neisseria meningitidis isolates contain a polysaccharide capsule that is the main virulence determinant for this bacterium. Thirteen capsular polysaccharides have been described, and nuclear magnetic resonance spectroscopy has enabled determination of the structure of capsular polysaccharides responsible for serogroup specificity. Molecular mechanisms involved in N. meningitidis capsule biosynthesis have also been identified, and genes involved in this process and in cell surface translocation are clustered at a single chromosomal locus termed cps. The use of multiple names for some of the genes involved in capsule synthesis, combined with the need for rapid diagnosis of serogroups commonly associated with invasive meningococcal disease, prompted a requirement for a consistent approach to the nomenclature of capsule genes. In this report, a comprehensive description of all N. meningitidis serogroups is provided, along with a proposed nomenclature, which was presented at the 2012 XVIIIth International Pathogenic Neisseria Conference.

Lipooligosaccharide Structures of Invasive and Carrier Isolates of Neisseria meningitidis Are Correlated with Pathogenicity and Carriage

“…The dramatic differences in serogroup are in general accord with previous studies of nasopharyngeal carriage during outbreaks of infection in Norway that showed only a few carriers that harbored the prevailing outbreak strain (17,18). The W and Y serogroup capsular polysaccharides are composed of alternating sialic acid moieties linked to D-galactose or D-glucose, respectively (19).…”

Dissection of Hexosyl- and Sialyltransferase Domains in the Bifunctional Capsule Polymerases from Neisseria meningitidis W and Y Defines a New Sialyltransferase Family

“…Group II capsules are characterized by polysaccharides with a high charge density and export via an ATPbinding cassette transporter-dependent system (6). Neisseria meningitidis (also referred to as meningococcus), a group of strictly human pathogens, produce group II capsules and are divided into 12 serogroups based on the chemical properties of the capsular polysaccharides (CPSs) 4 (7). Six of these serogroups (A, B, C, W, X, and Y) are important pathogens (8) (the serogroup nomenclature is simplified according to Harrison et al (7)).…”

Spontaneous point mutations in the capsule synthesis locus leading to structural and functional changes of the capsule in serogroup A meningococcal populations

“…It was also negative in the HPAEC-PAD analysis (Table 1), confirming lack of polysaccharide expression. Equally negative in both assays (Table 1) was isolate 2389 with a stop codon in the csaD gene encoding a protein predicted to be involved in either capsule transport or in cross-linking of the capsule to the meningococcal cell surface [16]. In contrast, isolate 1573 harbouring a non-synonymous mutation in the ctrD gene, encoding an ATP binding protein involved in capsule transport [16], showed no phenotypic changes and a normal amount of capsule (42.2 µg/mL/OD; Table 1).…”

“…The capsular genes are clustered within the cps chromosomal locus and divided into six regions, designated A-D, D’ and E. Genes in region A ( csaABCD ) encode for polysaccharide biosynthesis and polymerization enzymes [16]. Proteins encoded by genes in region B ( ctrE and ctrF ) and C ( ctrABCD ) are involved in translocation of the polysaccharide from the cytoplasm to the cell surface.…”

“…The function of region E is unknown. The serogroup A polysaccharide consists of repeating units of (α1-6)-linked N- acetyl-mannosamine-1-phosphate synthesized by enzymes encoded by genes designated mynA-D or csaA-D [16–18]. The repeating units are O-acetylated mainly at position C3 and sometimes at position C4 [17].…”