title: A basis for vaccine development: Comparative characterization of Haemophilus influenzae outer membrane vesicles.
abstract: Outer membrane vesicles (OMVs) are spherical and bilayered particles that are naturally released from the outer membrane (OM) of Gram-negative bacteria. They have been proposed to possess several biological roles in pathogenesis and interbacterial interactions. Additionally, OMVs have been suggested as potential vaccine candidates against infections caused by pathogenic bacteria like Haemophilus influenzae, a human pathogen of the respiratory tract. Unfortunately, there is still a lack of fundamental knowledge regarding OMV biogenesis, protein sorting into OMVs, OMV size and quantity, as well as OMV composition in H. influenzae. Thus, this study comprehensively characterized and compared OMVs and OMs derived from heterologous encapsulated as well as nonencapsulated H. influenzae strains. Semiquantitative immunoblot analysis revealed that certain OM proteins are enriched or excluded in OMVs suggesting the presence of regulated protein sorting mechanisms into OMVs as well as interconnected OMV biogenesis mechanisms in H. influenzae. Nanoparticle tracking analysis, transmission electron microscopy, as well as protein and lipooligosaccharide quantifications demonstrated that heterologous H. influenzae strains differ in their OMV size and quantity. Lipidomic analyses identified palmitic acid as the most abundant fatty acid, while phosphatidylethanolamine was found to be the most dominant phospholipid present in OMVs and the OM of all strains tested. Proteomic analysis confirmed that H. influenzae OMVs contain vaccine candidate proteins as well as important virulence factors. These findings contribute to the understanding of OMV biogenesis as well as biological roles of OMVs and, in addition, may be important for the future development of OMV based vaccines against H. influenzae infections.
authors.affiliation: Institute of Molecular Biosciences, University of Graz, NAWI Graz, BioTechMed-Graz, Humboldtstraße 50, A-8010 Graz, Austria.
authors.forename: Sandro
authors.initials: S
authors.lastname: Roier
authors.affiliation: Institute of Molecular Biosciences, University of Graz, NAWI Graz, BioTechMed-Graz, Humboldtstraße 50, A-8010 Graz, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Blume
authors.affiliation: Institute of Biochemistry, Graz University of Technology, NAWI Graz, BioTechMed-Graz, Petersgasse 12/2, A-8010 Graz, Austria.
authors.forename: Lisa
authors.initials: L
authors.lastname: Klug
authors.affiliation: Institute of Chemistry/Organic and Bioorganic Chemistry, University of Graz, NAWI Graz, BioTechMed-Graz, Heinrichstraße 28, A-8010 Graz, Austria.
authors.forename: Gabriel E
authors.initials: GE
authors.lastname: Wagner
authors.affiliation: Alberta Glycomics Centre, Department of Biological Sciences, University of Alberta, CW405 Biological Sciences Building, Edmonton, AB, Canada T6G 2E9.
authors.forename: Wael
authors.initials: W
authors.lastname: Elhenawy
authors.affiliation: Institute of Chemistry/Organic and Bioorganic Chemistry, University of Graz, NAWI Graz, BioTechMed-Graz, Heinrichstraße 28, A-8010 Graz, Austria.
authors.forename: Klaus
authors.initials: K
authors.lastname: Zangger
authors.affiliation: Institute of Biophysics, Medical University of Graz, BioTechMed-Graz, Harrachgasse 21, A-8010 Graz, Austria.
authors.forename: Ruth
authors.initials: R
authors.lastname: Prassl
authors.affiliation: Institute of Molecular Biosciences, University of Graz, NAWI Graz, BioTechMed-Graz, Humboldtstraße 50, A-8010 Graz, Austria.
authors.forename: Joachim
authors.initials: J
authors.lastname: Reidl
authors.affiliation: Institute of Biochemistry, Graz University of Technology, NAWI Graz, BioTechMed-Graz, Petersgasse 12/2, A-8010 Graz, Austria.
authors.forename: Günther
authors.initials: G
authors.lastname: Daum
authors.affiliation: Alberta Glycomics Centre, Department of Biological Sciences, University of Alberta, CW405 Biological Sciences Building, Edmonton, AB, Canada T6G 2E9.
authors.forename: Mario F
authors.initials: MF
authors.lastname: Feldman
authors.affiliation: Institute of Molecular Biosciences, University of Graz, NAWI Graz, BioTechMed-Graz, Humboldtstraße 50, A-8010 Graz, Austria. Electronic address: stefan.schild@uni-graz.at.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schild
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000032:analysis* / Q000276:immunology; D001428:Bacterial Vaccines / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D055354:Exosomes / Q000737:chemistry* / Q000648:ultrastructure; D006193:Haemophilus influenzae / Q000737:chemistry* / Q000648:ultrastructure; D008055:Lipids / Q000032:analysis; D008070:Lipopolysaccharides / Q000032:analysis; D008807:Mice, Inbred BALB C; D020543:Proteome / Q000032:analysis* / Q000276:immunology
chemical_list: D000942:Antigens, Bacterial; D001428:Bacterial Vaccines; D008055:Lipids; D008070:Lipopolysaccharides; D020543:Proteome; C023023:lipid-linked oligosaccharides
keywords: Hib; Lipidome; NTHi; OMV; Protein sorting; Proteome