Identification, Characterization and Immunogenicity of an O-Antigen Capsular Polysaccharide of Francisella tularensis

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Title Identification, Characterization and Immunogenicity of an O-Antigen Capsular Polysaccharide of Francisella tularensis
Author Apicella, Michael A.; Post, Deborah M. B.; Fowler, Andrew C.; Jones, Bradley D.; Rasmussen, Jed A.; Hunt, Jason R.; Imagawa, Sayaka; Choudhury, Biswa; Inzana, Thomas J.; Maier, Tamara M.; Frank, Dara W.; Zahrt, Thomas C.; Chaloner, Kathryn; Jennings, Michael Paul; McLendon, Molly K.; Gibson, Bradford W.
Journal Name PLoS ONE
Year Published 2010
Place of publication United States
Publisher Public Library of Science
Abstract Capsular polysaccharides are important factors in bacterial pathogenesis and have been the target of a number of successful vaccines. Francisella tularensis has been considered to express a capsular antigen but none has been isolated or characterized. We have developed a monoclonal antibody, 11B7, which recognizes the capsular polysaccharide of F. tularensis migrating on Western blot as a diffuse band between 100 kDa and 250 kDa. The capsule stains poorly on SDS-PAGE with silver stain but can be visualized using ProQ Emerald glycoprotein stain. The capsule appears to be highly conserved among strains of F. tularensis as antibody 11B7 bound to the capsule of 14 of 14 F. tularensis type A and B strains on Western blot. The capsular material can be isolated essentially free of LPS, is phenol and proteinase K resistant, ethanol precipitable and does not dissociate in sodium dodecyl sulfate. Immunoelectron microscopy with colloidal gold demonstrates 11B7 circumferentially staining the surface of F. tularensis which is typical of a polysaccharide capsule. Mass spectrometry, compositional analysis and NMR indicate that the capsule is composed of a polymer of the tetrasaccharide repeat, 4)-α-D-GalNAcAN-(1->4)-α-D-GalNAcAN-(1->​3)-β-D-QuiNAc-(1->2)-β-D-Qui4NFm-(1-,which is identical to the previously described F. tularensis O-antigen subunit. This indicates that the F. tularensis capsule can be classified as an O-antigen capsular polysaccharide. Our studies indicate that F. tularensis O-antigen glycosyltransferase mutants do not make a capsule. An F. tularensis acyltransferase and an O-antigen polymerase mutant had no evidence of an O-antigen but expressed a capsular antigen. Passive immunization of BALB/c mice with 75 µg of 11B7 protected against a 150 fold lethal challenge of F. tularensis LVS. Active immunization of BALB/c mice with 10 µg of capsule showed a similar level of protection. These studies demonstrate that F. tularensis produces an O-antigen capsule that may be the basis of a future vaccine
Peer Reviewed Yes
Published Yes
Alternative URI http://dx.doi.org/10.1371/journal.pone.0011060
Copyright Statement Copyright 2010 Apicella et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution License CCAL. (http://www.plos.org/journals/license.html)
Volume 5
Issue Number 7
Page from 1
Page to 18
ISSN 1932-6203
Date Accessioned 2010-11-26
Language en_AU
Research Centre Institute for Glycomics
Faculty Faculty of Science, Environment, Engineering and Technology
Subject Medical and Health Sciences
URI http://hdl.handle.net/10072/36904
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1

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