title: Comparative Genome Sequencing Reveals Within-Host Genetic Changes in Neisseria meningitidis during Invasive Disease.
abstract: Some members of the physiological human microbiome occasionally cause life-threatening disease even in immunocompetent individuals. A prime example of such a commensal pathogen is Neisseria meningitidis, which normally resides in the human nasopharynx but is also a leading cause of sepsis and epidemic meningitis. Using N. meningitidis as model organism, we tested the hypothesis that virulence of commensal pathogens is a consequence of within host evolution and selection of invasive variants due to mutations at contingency genes, a mechanism called phase variation. In line with the hypothesis that phase variation evolved as an adaptation to colonize diverse hosts, computational comparisons of all 27 to date completely sequenced and annotated meningococcal genomes retrieved from public databases showed that contingency genes are indeed enriched for genes involved in host interactions. To assess within-host genetic changes in meningococci, we further used ultra-deep whole-genome sequencing of throat-blood strain pairs isolated from four patients suffering from invasive meningococcal disease. We detected up to three mutations per strain pair, affecting predominantly contingency genes involved in type IV pilus biogenesis. However, there was not a single (set) of mutation(s) that could invariably be found in all four pairs of strains. Phenotypic assays further showed that these genetic changes were generally not associated with increased serum resistance, higher fitness in human blood ex vivo or differences in the interaction with human epithelial and endothelial cells in vitro. In conclusion, we hypothesize that virulence of meningococci results from accidental emergence of invasive variants during carriage and without within host evolution of invasive phenotypes during disease progression in vivo.
authors.affiliation: CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria.|Institute for Hygiene and Microbiology, University of Würzburg, Würzburg, Germany.
authors.forename: Johanna
authors.initials: J
authors.lastname: Klughammer
authors.affiliation: Department of Bioinformatics, Biocenter, University of Würzburg, Würzburg, Germany.|Institute of Human Genetics, Biocenter, University of Würzburg, Würzburg, Germany.
authors.forename: Marcus
authors.initials: M
authors.lastname: Dittrich
authors.affiliation: Institute for Bioinformatics and Systems Biology, Justus Liebig University Giessen, Giessen, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Blom
authors.affiliation: Institute for Hygiene and Microbiology, University of Würzburg, Würzburg, Germany.
authors.forename: Vera
authors.initials: V
authors.lastname: Mitesser
authors.affiliation: Institute for Hygiene and Microbiology, University of Würzburg, Würzburg, Germany.|Research Center for Infectious Diseases, University of Würzburg, Würzburg, Germany.|German Reference Laboratory for Meningococci and Haemophilus influenzae, Institute for Hygiene and Microbiology, University of Würzburg, Würzburg, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Vogel
authors.affiliation: Institute for Hygiene and Microbiology, University of Würzburg, Würzburg, Germany.|Research Center for Infectious Diseases, University of Würzburg, Würzburg, Germany.|German Reference Laboratory for Meningococci and Haemophilus influenzae, Institute for Hygiene and Microbiology, University of Würzburg, Würzburg, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Frosch
authors.affiliation: Institute for Bioinformatics and Systems Biology, Justus Liebig University Giessen, Giessen, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Goesmann
authors.affiliation: Department of Bioinformatics, Biocenter, University of Würzburg, Würzburg, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Müller
authors.affiliation: Institute for Hygiene and Microbiology, University of Würzburg, Würzburg, Germany.|Research Center for Infectious Diseases, University of Würzburg, Würzburg, Germany.
authors.forename: Christoph
authors.identifier: http://orcid.org/0000-0003-2222-1085
authors.initials: C
authors.lastname: Schoen
mesh_terms: D002460:Cell Line; D019143:Evolution, Molecular; D005260:Female; D016680:Genome, Bacterial; D059014:High-Throughput Nucleotide Sequencing; D054884:Host-Pathogen Interactions / Q000235:genetics*; D006801:Humans; D008297:Male; D008589:Meningococcal Infections / Q000235:genetics*; D009154:Mutation; D009345:Neisseria meningitidis / Q000472:pathogenicity / Q000502:physiology