title: Meningococcal biofilm growth on an abiotic surface - a model for epithelial colonization?
abstract: Neisseria meningitidis colonizes the human nasopharynx asymptomatically, often for prolonged periods, but occasionally invades from this site to cause life-threatening infection. In the nasopharynx aggregated organisms are closely attached to the epithelial surface, in a state in which the expression of components of the bacterial envelope differs significantly from that found in organisms multiplying exponentially in liquid phase culture or in the blood. We and others have hypothesized that here they are in the biofilm state, and to explore this we have investigated biofilm formation by the serogroup B strain MC58 on an abiotic surface, in a sorbarod system. Transcriptional changes were analysed, focusing on alteration in gene expression relevant to polysaccharide capsulation, lipooligosaccharide and outer-membrane protein synthesis - all phenotypes of importance in epithelial colonization. We report downregulation of genes controlling capsulation and the production of core oligosaccharide, and upregulation of genes encoding a range of outer-membrane components, reflecting phenotypic changes that have been established to occur in the colonizing state. A limited comparison with organisms recovered from an extended period of co-cultivation with epithelial cells suggests that this model system may better mirror natural colonization than do short-term meningococcal/epithelial cell co-cultivation systems. Modelling prolonged meningococcal colonization with a sorbarod system offers insight into gene expression during this important, but experimentally relatively inaccessible, phase of human infection.
authors.affiliation: Molecular Infectious Diseases Group, Department of Paediatrics, Faculty of Medicine, Imperial College London, Wright-Fleming Institute, St Mary's Hospital Campus, Norfolk Place, London W2 1PG, UK.
authors.forename: Clíona A
authors.initials: CA
authors.lastname: O'Dwyer
authors.affiliation: Molecular Infectious Diseases Group, Department of Paediatrics, Faculty of Medicine, Imperial College London, Wright-Fleming Institute, St Mary's Hospital Campus, Norfolk Place, London W2 1PG, UK.
authors.forename: Ming-Shi
authors.initials: MS
authors.lastname: Li
authors.affiliation: Molecular Infectious Diseases Group, Department of Paediatrics, Faculty of Medicine, Imperial College London, Wright-Fleming Institute, St Mary's Hospital Campus, Norfolk Place, London W2 1PG, UK.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Langford
authors.affiliation: Molecular Infectious Diseases Group, Department of Paediatrics, Faculty of Medicine, Imperial College London, Wright-Fleming Institute, St Mary's Hospital Campus, Norfolk Place, London W2 1PG, UK.
authors.forename: J Simon
authors.initials: JS
authors.lastname: Kroll
mesh_terms: D016667:Bacterial Capsules / Q000235:genetics / Q000378:metabolism; D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis / Q000235:genetics; D018441:Biofilms / Q000254:growth & development*; D018929:Cell Culture Techniques; D004847:Epithelial Cells / Q000382:microbiology*; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006801:Humans; D008070:Lipopolysaccharides / Q000096:biosynthesis / Q000235:genetics; D008589:Meningococcal Infections / Q000382:microbiology*; D008954:Models, Biological; D009305:Nasopharynx / Q000166:cytology / Q000382:microbiology; D038541:Neisseria meningitidis, Serogroup B / Q000502:physiology*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D008070:Lipopolysaccharides; C023023:lipid-linked oligosaccharides