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Description and Nomenclature of Neisseria meningitidis Capsule Locus - Vol. 19 No. 4 - April 2013 - Emerging Infectious Disease journal - CDC

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Description and Nomenclature of Neisseria meningitidis Capsule Locus - Vol. 19 No. 4 - April 2013 - Emerging Infectious Disease journal - CDC


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Volume 19, Number 4 – April 2013

Volume 19, Number 4—April 2013

Research

Description and Nomenclature of Neisseria meningitidis Capsule Locus

Odile B. Harrison, Heike Claus, Ying Jiang, Julia S. Bennett, Holly B. Bratcher, Keith A. Jolley, Craig Corton, Rory Care, Jan T. Poolman, Wendell D. Zollinger, Carl E. Frasch, David S. Stephens, Ian Feavers, Matthias Frosch, Julian Parkhill, Ulrich Vogel, Michael A. Quail, Stephen D. Bentley, and Martin C.J. Maiden
Author affiliations: University of Oxford, Oxford, UK (O.B. Harrison, J.S. Bennett, H.B. Bratcher, K.A. Jolley, M.C.J. Maiden); University of Würzburg, Würzburg, Germany (H. Claus, M. Frosch, U. Vogel); The Sanger Institute, Cambridge, UK (Y. Jiang, C. Corton, J. Parkhill, M.A. Quail, S.D. Bentley); National Institute for Biological Standards and Control, Potters Bar, UK (R. Care, I. Feavers); Crucell, Leiden, the Netherlands (J.T. Poolman); Walter Reed Army Institute of Research, Silver Spring, Maryland, USA (W.D. Zollinger); Frasch Biologics Consulting, Martinsburg, West Virginia, USA (C.E. Frasch); Emory University, Atlanta, Georgia, USA (D.S. Stephens)
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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.
Thirteen Neisseria meningitidis serogroups have been described on the basis of serologic differences of the capsule; of these 13 serogroups, 6 (A, B, C, W, X, Y) cause invasive meningococcal disease. The polysaccharide capsule is a key virulence determinant, and for serogroups A, C, W, and Y, it forms the basis of polysaccharide conjugate vaccines. In one of the first reports distinguishing N. meningitidis, disease isolates were serologically classified into types I–IV on the basis of agglutination reactions with immune rabbit serum (1). In 1950, the subcommittee on Neisseria of the Nomenclature Committee of the International Association of Microbiologists recommended that types I and III be combined into serogroup A; type II become serogroup B; a type II subgroup, termed type II-α, become serogroup C; and type IV become serogroup D. After the report of a fourth serogroup, Z′ (later shown to be serogroup E), 3 new serogroups (X– Z) were identified by using double agar diffusion (2,3). In 1981, three more serogroups (H, I, K) were proposed, and a fourth (serogroup L) was identified in 1983 (4,5).
Nuclear magnetic resonance spectroscopy enabled determination of the structure of capsular polysaccharides responsible for serogroup specificity, and structures for 12 of the 13 serogroups (all but serogroup D) from N. meningitidis capsular polysaccharides have been reported (615). Molecular mechanisms of capsular polysaccharide synthesis have been elucidated; genes involved in polysaccharide biosynthesis and cell surface translocation are clustered at a single chromosomal locus termed cps. Genes within this locus are divided into 6 regions: A–D, D′, and E (16). Genes in region A encode enzymes for biosynthesis of the capsular polysaccharide, and genes in regions B and C are implicated in the translocation of the high molecular weight polysaccharides to the cell surface.
Complete nucleotide sequences of cps loci encoding serogroups A–C, W, and Y have been elucidated. Serogroup-specific capsule biosynthesis genes located in region A have been published for serogroup X, and nucleotide sequences for serogroups E, L, and Z have been submitted to GenBank (accession nos. AJ576117, AF112478, and AJ744766, respectively) (1719). This study provides a comprehensive description of all N. meningitidis serogroups and presents proposed revisions to the nomenclature.

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