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1.
Int J Oral Sci ; 16(1): 37, 2024 May 11.
Article in English | MEDLINE | ID: mdl-38734663

ABSTRACT

Emerging regenerative cell therapies for alveolar bone loss have begun to explore the use of cell laden hydrogels for minimally invasive surgery to treat small and spatially complex maxilla-oral defects. However, the oral cavity presents a unique and challenging environment for in vivo bone tissue engineering, exhibiting both hard and soft periodontal tissue as well as acting as key biocenosis for many distinct microbial communities that interact with both the external environment and internal body systems, which will impact on cell fate and subsequent treatment efficacy. Herein, we design and bioprint a facile 3D in vitro model of a human dentine interface to probe the effect of the dentine surface on human mesenchymal stem cells (hMSCs) encapsulated in a microporous hydrogel bioink. We demonstrate that the dentine substrate induces osteogenic differentiation of encapsulated hMSCs, and that both dentine and ß-tricalcium phosphate substrates stimulate extracellular matrix production and maturation at the gel-media interface, which is distal to the gel-substrate interface. Our findings demonstrate the potential for long-range effects on stem cells by mineralized surfaces during bone tissue engineering and provide a framework for the rapid development of 3D dentine-bone interface models.


Subject(s)
Cell Differentiation , Dentin , Mesenchymal Stem Cells , Osteogenesis , Tissue Engineering , Humans , Osteogenesis/physiology , Tissue Engineering/methods , Calcium Phosphates , Hydrogels , In Vitro Techniques , Bioprinting , Tissue Scaffolds , Surface Properties , Extracellular Matrix , Cells, Cultured
2.
Macromol Rapid Commun ; : e2400345, 2024 May 17.
Article in English | MEDLINE | ID: mdl-38760014

ABSTRACT

The need for wound closure or surgical procedures has been commonly met by application of sutures. Unfortunately, these are often invasive or subject to contamination (and consequent infection and negative impact on patients). Alternative solutions are offered by surgical adhesives that can be applied and set without major disruption; a new class of supramolecular-based adhesives provide potential solutions to some of these challenges. In this study a series of polymers utilising dopamine as a self-assembling unit were synthesized. It was found that these motifs act as extremely effective adhesives, with control over the mechanical strength of the adhesion and materials' tensile properties enabled by changing monomer feed ratios and levels of crosslinking. These materials significantly outperform commercially available bio-adhesives, showing yield strengths after adhesion at least 2 times higher than that of BioGlue and Tisseel, as well as the ability to re-adhere with significant recovery of adhesion strength. Promisingly, the materials were shown to be non-cytotoxic, with cell viability > 90%, and able to perform in aqueous environments without significant loss in strength. Finally, the removal of the materials, after use as an adhesive, was possible using benign organic solvents such as ethanol, ensuring recyclability. These properties all demonstrate the effectiveness of the materials as potential bio-adhesives, with potential advantages for use in surgery. This article is protected by copyright. All rights reserved.

3.
Nat Commun ; 15(1): 3487, 2024 Apr 25.
Article in English | MEDLINE | ID: mdl-38664424

ABSTRACT

An improved understanding of the underlying physicochemical properties of respiratory aerosol that influence viral infectivity may open new avenues to mitigate the transmission of respiratory diseases such as COVID-19. Previous studies have shown that an increase in the pH of respiratory aerosols following generation due to changes in the gas-particle partitioning of pH buffering bicarbonate ions and carbon dioxide is a significant factor in reducing SARS-CoV-2 infectivity. We show here that a significant increase in SARS-CoV-2 aerostability results from a moderate increase in the atmospheric carbon dioxide concentration (e.g. 800 ppm), an effect that is more marked than that observed for changes in relative humidity. We model the likelihood of COVID-19 transmission on the ambient concentration of CO2, concluding that even this moderate increase in CO2 concentration results in a significant increase in overall risk. These observations confirm the critical importance of ventilation and maintaining low CO2 concentrations in indoor environments for mitigating disease transmission. Moreover, the correlation of increased CO2 concentration with viral aerostability need to be better understood when considering the consequences of increases in ambient CO2 levels in our atmosphere.


Subject(s)
COVID-19 , Carbon Dioxide , SARS-CoV-2 , Carbon Dioxide/metabolism , Carbon Dioxide/analysis , COVID-19/transmission , COVID-19/virology , Humans , Hydrogen-Ion Concentration , Aerosols , Humidity , Ventilation , Respiratory Aerosols and Droplets/metabolism , Respiratory Aerosols and Droplets/virology , Atmosphere/chemistry
4.
J R Soc Interface ; 20(203): 20230062, 2023 06.
Article in English | MEDLINE | ID: mdl-37340783

ABSTRACT

The mechanistic factors hypothesized to be key drivers for the loss of infectivity of viruses in the aerosol phase often remain speculative. Using a next-generation bioaerosol technology, we report measurements of the aero-stability of several SARS-CoV-2 variants of concern in aerosol droplets of well-defined size and composition at high (90%) and low (40%) relative humidity (RH) upwards of 40 min. When compared with the ancestral virus, the infectivity of the Delta variant displayed different decay profiles. At low RH, a loss of viral infectivity of approximately 55% was observed over the initial 5 s for both variants. Regardless of RH and variant, greater than 95% of the viral infectivity was lost after 40 min of being aerosolized. Aero-stability of the variants correlate with their sensitivities to alkaline pH. Removal of all acidic vapours dramatically increased the rate of infectivity decay, with 90% loss after 2 min, while the addition of nitric acid vapour improved aero-stability. Similar aero-stability in droplets of artificial saliva and growth medium was observed. A model to predict loss of viral infectivity is proposed: at high RH, the high pH of exhaled aerosol drives viral infectivity loss; at low RH, high salt content limits the loss of viral infectivity.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , SARS-CoV-2/genetics , COVID-19/epidemiology , Respiratory Aerosols and Droplets
5.
Viruses ; 14(9)2022 08 24.
Article in English | MEDLINE | ID: mdl-36146663

ABSTRACT

Respiratory pathogens can be spread though the transmission of aerosolised expiratory secretions in the form of droplets or particulates. Understanding the fundamental aerosol parameters that govern how such pathogens survive whilst airborne is essential to understanding and developing methods of restricting their dissemination. Pathogen viability measurements made using Controlled Electrodynamic Levitation and Extraction of Bioaerosol onto Substrate (CELEBS) in tandem with a comparative kinetics electrodynamic balance (CKEDB) measurements allow for a direct comparison between viral viability and evaporation kinetics of the aerosol with a time resolution of seconds. Here, we report the airborne survival of mouse hepatitis virus (MHV) and determine a comparable loss of infectivity in the aerosol phase to our previous observations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Through the addition of clinically relevant concentrations of mucin to the bioaerosol, there is a transient mitigation of the loss of viral infectivity at 40% RH. Increased concentrations of mucin promoted heterogenous phase change during aerosol evaporation, characterised as the formation of inclusions within the host droplet. This research demonstrates the role of mucus in the aerosol phase and its influence on short-term airborne viral stability.


Subject(s)
COVID-19 , SARS-CoV-2 , Animals , Mice , Microbial Viability , Mucins , Respiratory Aerosols and Droplets
7.
Microbiology (Reading) ; 168(8)2022 08.
Article in English | MEDLINE | ID: mdl-35920810

ABSTRACT

Neisseria gonorrhoeae, the causative agent of gonorrhoea, is a major burden on global healthcare systems, with an estimated ~80-90 million new global cases annually. This burden is exacerbated by increasing levels of antimicrobial resistance, which has greatly limited viable antimicrobial therapies. Decreasing gonococcal drug susceptibility has been driven largely by accumulation of chromosomal resistance determinants, which can be acquired through natural transformation, whereby DNA in the extracellular milieu is imported into cells and incorporated into the genome by homologous recombination. N. gonorrhoeae possesses a specialized system for DNA uptake, which strongly biases transformation in favour of DNA from closely related bacteria by recognizing a 10-12 bp DNA uptake sequence (DUS) motif, which is highly overrepresented in their chromosomal DNA. This process relies on numerous proteins, including the DUS-specific receptor ComP, which assemble retractile protein filaments termed type IV pili (T4P) extending from the cell surface, and one model for neisserial DNA uptake proposes that these filaments bind DNA in a DUS-dependent manner before retracting to transport DNA into the periplasm. However, conflicting evidence indicates that elongated pilus filaments may not have such a direct role in DNA binding uptake as this model suggests. Here, we quantitatively measured DNA binding to gonococcal T4P fibres by directly visualizing binding complexes with confocal fluorescence microscopy in order to confirm the sequence-specific, comP-dependent DNA binding capacity of elongated T4P fibres. This supports the idea that pilus filaments could be responsible for initially capturing DNA in the first step of sequence-specific DNA uptake.


Subject(s)
Gonorrhea , Transformation, Bacterial , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , DNA, Bacterial/genetics , DNA, Bacterial/metabolism , Fimbriae Proteins/genetics , Fimbriae Proteins/metabolism , Fimbriae, Bacterial/genetics , Fimbriae, Bacterial/metabolism , Gonorrhea/metabolism , Humans , Neisseria gonorrhoeae/genetics , Neisseria gonorrhoeae/metabolism
8.
Front Cell Infect Microbiol ; 12: 920447, 2022.
Article in English | MEDLINE | ID: mdl-35873173

ABSTRACT

The rapid spread of antimicrobial resistant Neisseria gonorrhoeae continues to pose a serious threat to global health. To successfully treat and control gonococcal infections, rapid diagnosis is critical. Currently, nucleic acid amplification tests are the recommended diagnostic, however, these are both technically demanding and time consuming, making them unsuitable for resource-poor clinics. Consequently, there is a substantial need for an affordable, point-of-care diagnostic to use in these settings. In this study, DNA-functionalised gold nanoparticles (gold nanoprobes), with the ability to specifically detect the DNA Uptake Sequence (DUS) of Neisseria gonorrhoeae, were prepared. Using complementary annealing, the gold nanoprobes were shown to hybridise to genomic gonococcal DNA, causing a significant shift in their salt stability. By exploiting the shift in nanoprobe stability under the presence of target DNA, a solution-based colorimetric diagnostic for gonococcal DNA was prepared. Detection of purified genomic DNA was achieved in under 30 minutes, with a detection limit of 15.0 ng. Significantly, testing with DNA extracted from an off-target control organism suggested specificity for Neisseria. These results highlight the potential of DUS-specific gold nanoprobes in the rapid point-of-care diagnosis of gonococcal infections.


Subject(s)
Gonorrhea , Metal Nanoparticles , Anti-Bacterial Agents/pharmacology , DNA , Drug Resistance, Bacterial , Genomics , Gold , Gonorrhea/diagnosis , Humans , Microbial Sensitivity Tests , Neisseria gonorrhoeae/genetics
9.
Proc Natl Acad Sci U S A ; 119(27): e2200109119, 2022 07 05.
Article in English | MEDLINE | ID: mdl-35763573

ABSTRACT

Understanding the factors that influence the airborne survival of viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in aerosols is important for identifying routes of transmission and the value of various mitigation strategies for preventing transmission. We present measurements of the stability of SARS-CoV-2 in aerosol droplets (∼5 to 10 µm equilibrated radius) over timescales spanning 5 s to 20 min using an instrument to probe survival in a small population of droplets (typically 5 to 10) containing ∼1 virus/droplet. Measurements of airborne infectivity change are coupled with a detailed physicochemical analysis of the airborne droplets containing the virus. A decrease in infectivity to ∼10% of the starting value was observable for SARS-CoV-2 over 20 min, with a large proportion of the loss occurring within the first 5 min after aerosolization. The initial rate of infectivity loss was found to correlate with physical transformation of the equilibrating droplet; salts within the droplets crystallize at relative humidities (RHs) below 50%, leading to a near-instant loss of infectivity in 50 to 60% of the virus. However, at 90% RH, the droplet remains homogenous and aqueous, and the viral stability is sustained for the first 2 min, beyond which it decays to only 10% remaining infectious after 10 min. The loss of infectivity at high RH is consistent with an elevation in the pH of the droplets, caused by volatilization of CO2 from bicarbonate buffer within the droplet. Four different variants of SARS-CoV-2 were compared and found to have a similar degree of airborne stability at both high and low RH.


Subject(s)
Aerosolized Particles and Droplets , COVID-19 , SARS-CoV-2 , Aerosolized Particles and Droplets/chemistry , Aerosolized Particles and Droplets/isolation & purification , COVID-19/transmission , Humans , Humidity , Hydrogen-Ion Concentration , SARS-CoV-2/isolation & purification , SARS-CoV-2/pathogenicity
10.
Clin Sci (Lond) ; 135(24): 2667-2689, 2021 12 22.
Article in English | MEDLINE | ID: mdl-34807265

ABSTRACT

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes a broad range of clinical responses including prominent microvascular damage. The capacity of SARS-CoV-2 to infect vascular cells is still debated. Additionally, the SARS-CoV-2 Spike (S) protein may act as a ligand to induce non-infective cellular stress. We tested this hypothesis in pericytes (PCs), which are reportedly reduced in the heart of patients with severe coronavirus disease-2019 (COVID-19). Here we newly show that the in vitro exposure of primary human cardiac PCs to the SARS-CoV-2 wildtype strain or the α and δ variants caused rare infection events. Exposure to the recombinant S protein alone elicited signalling and functional alterations, including: (1) increased migration, (2) reduced ability to support endothelial cell (EC) network formation on Matrigel, (3) secretion of pro-inflammatory molecules typically involved in the cytokine storm, and (4) production of pro-apoptotic factors causing EC death. Next, adopting a blocking strategy against the S protein receptors angiotensin-converting enzyme 2 (ACE2) and CD147, we discovered that the S protein stimulates the phosphorylation/activation of the extracellular signal-regulated kinase 1/2 (ERK1/2) through the CD147 receptor, but not ACE2, in PCs. The neutralisation of CD147, either using a blocking antibody or mRNA silencing, reduced ERK1/2 activation, and rescued PC function in the presence of the S protein. Immunoreactive S protein was detected in the peripheral blood of infected patients. In conclusion, our findings suggest that the S protein may prompt PC dysfunction, potentially contributing to microvascular injury. This mechanism may have clinical and therapeutic implications.


Subject(s)
Angiotensin-Converting Enzyme 2/metabolism , Basigin/metabolism , Myocardium/enzymology , Pericytes/enzymology , SARS-CoV-2/physiology , Spike Glycoprotein, Coronavirus/blood , Adolescent , Adult , Aged , Aged, 80 and over , COVID-19/blood , Caco-2 Cells , Cell Death , Child , Child, Preschool , Cytokines/metabolism , Female , Host-Pathogen Interactions , Humans , Infant , Infant, Newborn , Male , Middle Aged , Myocardium/cytology , Pericytes/virology , Primary Cell Culture , Young Adult
11.
Microb Genom ; 6(5)2020 05.
Article in English | MEDLINE | ID: mdl-32375974

ABSTRACT

Mobile genetic elements (MGEs) are key factors responsible for dissemination of virulence determinants and antimicrobial-resistance genes amongst pathogenic bacteria. Conjugative MGEs are notable for their high gene loads donated per transfer event, broad host ranges and phylogenetic ubiquity amongst prokaryotes, with the subclass of chromosomally inserted integrative and conjugative elements (ICEs) being particularly abundant. The focus on a small number of model systems has biased the study of ICEs towards those conferring readily selectable phenotypes to host cells, whereas the identification and characterization of integrated cryptic elements remains challenging. Even though antimicrobial resistance and horizontally acquired virulence genes are major factors aggravating neisserial infection, conjugative MGEs of Neisseria gonorrhoeae and Neisseria meningitidis remain poorly characterized. Using a phenotype-independent approach based on atypical distributions of DNA uptake sequences (DUSs) in MGEs relative to the chromosomal background, we have identified two groups of chromosomally integrated conjugative elements in Neisseria: one found almost exclusively in pathogenic species possibly deriving from the genus Kingella, the other belonging to a group of Neisseria mucosa-like commensals. The former element appears to enable transfer of traditionally gonococcal-specific loci such as the virulence-associated toxin-antitoxin system fitAB to N. meningitidis chromosomes, whilst the circular form of the latter possesses a unique attachment site (attP) sequence seemingly adapted to exploit DUS motifs as chromosomal integration sites. In addition to validating the use of DUS distributions in Neisseriaceae MGE identification, the >170 identified ICE sequences provide a valuable resource for future studies of ICE evolution and host adaptation.


Subject(s)
Chromosomes, Bacterial/genetics , DNA Transposable Elements , Neisseriaceae/classification , Plasmids/genetics , Sequence Analysis, DNA/methods , Conjugation, Genetic , Drug Resistance, Multiple, Bacterial , Evolution, Molecular , Gene Transfer, Horizontal , High-Throughput Nucleotide Sequencing , Neisseriaceae/genetics , Neisseriaceae/isolation & purification , Neisseriaceae/pathogenicity , Phenotype , Phylogeny , Symbiosis , Virulence Factors/genetics , Vocabulary
12.
Sex Health ; 16(5): 514-522, 2019 09.
Article in English | MEDLINE | ID: mdl-31476277

ABSTRACT

Background Antimicrobial-resistant (AMR) gonorrhoea is a global public health threat. Discriminatory point-of-care tests (POCT) to detect drug sensitivity are under development, enabling individualised resistance-guided therapy. METHODS: An individual-based dynamic transmission model of gonorrhoea infection in MSM living in London has been developed, incorporating ciprofloxacin-sensitive and resistant strains. The time-dependent sexual contact network is captured by periodically restructuring active connections to reflect the transience of contacts. Different strategies to improve treatment selection were explored, including discriminatory POCT and selecting partner treatment based on either the index case or partner susceptibility. Outcomes included population prevalence of gonorrhoea and drug dose counts. RESULTS: It is shown that using POCT to detect ciprofloxacin-sensitive infections could result in a large decrease in ceftriaxone doses (by 70% compared with the reference case in the simulations of this study). It also suggests that ceftriaxone use can be reduced with existing technologies, albeit to a lesser degree; either using index case sensitivity profiles to direct treatment of partners, or testing notified partners with strain discriminatory laboratory tests before treatment, reduced ceftriaxone use in our model (by 27% and 47% respectively). CONCLUSIONS: POCT to detect ciprofloxacin-sensitive gonorrhoea are likely to dramatically reduce reliance on ceftriaxone, but requires the implementation of new technology. In the meantime, the proportion of unnecessary ceftriaxone treatment by testing partners before treatment could be reduced significantly. Alternatively, index case sensitivity profiles could be used to select effective treatments for partners.


Subject(s)
Anti-Bacterial Agents/therapeutic use , Gonorrhea/transmission , Homosexuality, Male/statistics & numerical data , Neisseria gonorrhoeae/drug effects , Ceftriaxone/therapeutic use , Ciprofloxacin/therapeutic use , Drug Resistance, Bacterial , Gonorrhea/diagnosis , Gonorrhea/drug therapy , Homosexuality, Male/psychology , Humans , London/epidemiology , Male , Models, Statistical , Point-of-Care Testing
13.
J Oral Microbiol ; 11(1): 1565043, 2019.
Article in English | MEDLINE | ID: mdl-30719234

ABSTRACT

Neisseria meningitidis, Haemophilus influenzae, and Moraxella catarrhalis are pathogenic bacteria adapted to reside on human respiratory mucosal epithelia. One common feature of these species is their ability to target members of the carcinoembryonic antigen-related cell adhesion molecule (CEACAM) family, especially CEACAM1, which is achieved via structurally distinct ligands expressed by each species. Beside respiratory epithelial cells, cells at the dentogingival junction express high levels of CEACAM1. It is possible that bacterial species resident within the oral cavity also utilise CEACAM1 for colonisation and invasion of gingival tissues. From a screen of 59 isolates from the human oral cavity representing 49 bacterial species, we identified strains from Fusobacterium bound to CEACAM1. Of the Fusobacterium species tested, the CEACAM1-binding property was exhibited by F. nucleatum (Fn) and F. vincentii (Fv) but not F. polymorphum (Fp) or F. animalis (Fa) strains tested. These studies identified that CEACAM adhesion was mediated using a trimeric autotransporter adhesin (TAA) for which no function has thus far been defined. We therefore propose the name CEACAM binding protein of Fusobacterium (CbpF). CbpF was identified to be present in the majority of unspeciated Fusobacterium isolates confirming a subset of Fusobacterium spp. are able to target human CEACAM1.

14.
PLoS One ; 13(3): e0193940, 2018.
Article in English | MEDLINE | ID: mdl-29547646

ABSTRACT

Neisseria meningitidis is an antigenically and genetically variable Gram-negative bacterium and a causative agent of meningococcal meningitis and septicaemia. Meningococci encode many outer membrane proteins, including Opa, Opc, Msf, fHbp and NadA, identified as being involved in colonisation of the host and evasion of the immune response. Although vaccines are available for the prevention of some types of meningococcal disease, none currently offer universal protection. We have used sequences within the Neisseria PubMLST database to determine the variability of msf and opc in 6,500 isolates. In-silico analysis revealed that although opc is highly conserved, it is not present in all isolates, with most isolates in clonal complex ST-11 lacking a functional opc. In comparison, msf is found in all meningococcal isolates, and displays diversity in the N-terminal domain. We identified 20 distinct Msf sequence variants (Msf SV), associated with differences in number of residues within the putative Vn binding motifs. Moreover, we showed distinct correlations with certain Msf SVs and isolates associated with either hyperinvasive lineages or those clonal complexes associated with a carriage state. We have demonstrated differences in Vn binding between three Msf SVs and generated a cross reactive Msf polyclonal antibody. Our study has highlighted the importance of using large datasets to inform vaccine development and provide further information on the antigenic diversity exhibited by N. meningitidis.


Subject(s)
Antigens, Bacterial/genetics , Bacterial Outer Membrane Proteins/genetics , Meningococcal Vaccines/genetics , Neisseria meningitidis/genetics , Adhesins, Bacterial/genetics , Amino Acid Sequence , Antigenic Variation/genetics , Computational Biology/methods , Genetic Variation/genetics , Humans , Meningitis, Meningococcal/immunology , Sequence Alignment
16.
Nat Microbiol ; 2: 16189, 2016 Oct 17.
Article in English | MEDLINE | ID: mdl-27748768

ABSTRACT

Helicobacter pylori specifically colonizes the human gastric epithelium and is the major causative agent for ulcer disease and gastric cancer development. Here, we identify members of the carcinoembryonic antigen-related cell adhesion molecule (CEACAM) family as receptors of H. pylori and show that HopQ is the surface-exposed adhesin that specifically binds human CEACAM1, CEACAM3, CEACAM5 and CEACAM6. HopQ-CEACAM binding is glycan-independent and targeted to the N-domain. H. pylori binding induces CEACAM1-mediated signalling, and the HopQ-CEACAM1 interaction enables translocation of the virulence factor CagA into host cells and enhances the release of pro-inflammatory mediators such as interleukin-8. Based on the crystal structure of HopQ, we found that a ß-hairpin insertion (HopQ-ID) in HopQ's extracellular 3+4 helix bundle domain is important for CEACAM binding. A peptide derived from this domain competitively inhibits HopQ-mediated activation of the Cag virulence pathway, as genetic or antibody-mediated abrogation of the HopQ function shows. Together, our data suggest the HopQ-CEACAM1 interaction to be a potentially promising novel therapeutic target to combat H. pylori-associated diseases.


Subject(s)
Adhesins, Bacterial/metabolism , Bacterial Adhesion , Cell Adhesion Molecules/metabolism , Helicobacter pylori/physiology , Helicobacter pylori/pathogenicity , Host-Pathogen Interactions , Adhesins, Bacterial/chemistry , Antigens, Bacterial/metabolism , Bacterial Proteins/metabolism , Cell Line , Crystallography, X-Ray , Humans , Interleukin-8/metabolism , Protein Binding , Protein Conformation , Protein Transport , Virulence
17.
Genome Biol Evol ; 8(4): 955-74, 2016 Apr 06.
Article in English | MEDLINE | ID: mdl-26912404

ABSTRACT

The bacterial speciesMoraxella catarrhalishas been hypothesized as being composed of two distinct lineages (referred to as the seroresistant [SR] and serosensitive [SS]) with separate evolutionary histories based on several molecular typing methods, whereas 16S ribotyping has suggested an additional split within the SS lineage. Previously, we characterized whole-genome sequences of 12 SR-lineage isolates, which revealed a relatively small supragenome when compared with other opportunistic nasopharyngeal pathogens, suggestive of a relatively short evolutionary history. Here, we performed whole-genome sequencing on 18 strains from both ribotypes of the SS lineage, an additional SR strain, as well as four previously identified highly divergent strains based on multilocus sequence typing analyses. All 35 strains were subjected to a battery of comparative genomic analyses which clearly show that there are three lineages-the SR, SS, and the divergent. The SR and SS lineages are closely related, but distinct from each other based on three different methods of comparison: Allelic differences observed among core genes; possession of lineage-specific sets of core and distributed genes; and by an alignment of concatenated core sequences irrespective of gene annotation. All these methods show that the SS lineage has much longer interstrain branches than the SR lineage indicating that this lineage has likely been evolving either longer or faster than the SR lineage. There is evidence of extensive horizontal gene transfer (HGT) within both of these lineages, and to a lesser degree between them. In particular, we identified very high rates of HGT between these two lineages for ß-lactamase genes. The four divergent strains aresui generis, being much more distantly related to both the SR and SS groups than these other two groups are to each other. Based on average nucleotide identities, gene content, GC content, and genome size, this group could be considered as a separate taxonomic group. The SR and SS lineages, although distinct, clearly form a single species based on multiple criteria including a large common core genome, average nucleotide identity values, GC content, and genome size. Although neither of these lineages arose from within the other based on phylogenetic analyses, the question of how and when these lineages split and then subsequently reunited in the human nasopharynx is explored.


Subject(s)
Genome, Bacterial , Moraxella catarrhalis/genetics , Cell Line , Evolution, Molecular , Genomics , Humans , Moraxella catarrhalis/growth & development , Moraxellaceae Infections/microbiology , Multigene Family , Phylogeny , Virulence Factors/genetics
18.
PLoS One ; 10(3): e0124133, 2015.
Article in English | MEDLINE | ID: mdl-25826209

ABSTRACT

The human pathogen Neisseria meningitides (Nm) attains serum resistance via a number of mechanisms, one of which involves binding to the host complement regulator protein vitronectin. We have shown previously that the Meningococcal surface fibril (Msf), a trimeric autotransporter, binds to the activated form of vitronectin (aVn) to increase Nm survival in human serum. In this study, we aimed to identify the aVn-binding region of Msf to assess its potential as an antigen which can elicit antibodies that block aVn binding and/or possess bactericidal properties. Using several recombinant Msf fragments spanning its surface-exposed region, the smallest aVn-binding recombinants were found to span residues 1-86 and 39-124. The use of further deletion constructs and overlapping recombinant Msf fragments suggested that a region of Msf comprising residues 39-82 may be primarily important for aVn binding and that other regions may also be involved but to a lesser extent. Molecular modelling implicated K66 and K68, conserved in all available Msf sequences, to be involved in the interaction. Recombinant fragments which bound to aVn were able to reduce the survival advantage conveyed by aVn-interaction in serum bactericidal assays. Antibodies raised against one such fragment inhibited aVn binding to Msf. In addition, the antibodies enhanced specific killing of Msf-expressing Nm in a dose-dependent manner. Overall, this study identifies an aVn-binding region of Msf, an adhesin known to impart serum resistance properties to the pathogen; and shows that this region of Msf can elicit antibodies with dual properties which reduce pathogen survival within the host and thus has potential as a vaccine antigen.


Subject(s)
Bacterial Proteins/metabolism , Neisseria meningitidis/metabolism , Vitronectin/metabolism , Amino Acid Sequence , Bacterial Proteins/chemistry , Bacterial Proteins/genetics , Binding Sites , Molecular Sequence Data
19.
PLoS One ; 9(3): e90999, 2014.
Article in English | MEDLINE | ID: mdl-24599281

ABSTRACT

Circulating monocytes in the bloodstream typically migrate to other tissues and differentiate into tissue resident macrophages, the process being determined by the constituents of the microenvironments encountered. These may include microbes and their products. In this study, we investigated whether Moraxella catarrhalis Ubiquitous Surface Protein A1 (UspA1), known to bind to a widely expressed human cell surface receptor CEACAM1, influences monocyte differentiation as receptor engagement has been shown to have profound effects on monocytes. We used the recombinant molecules corresponding to the regions of UspA1 which either bind (rD-7; UspA1527-665) or do not bind (r6-8; UspA1659-863) to CEACAM1 and investigated their effects on CD206, CD80 and CD86 expression on freshly isolated human CD14+ monocytes from peripheral blood mononuclear cells (PBMC). Exposure to rD-7, but not r6-8, biased monocyte differentiation towards a CD14+CD206+ phenotype, with reduced CD80 expression. Monocytes treated with rD-7 also secreted high levels of IL-1ra and chemokine IL-8 but not IL-10 or IL-12p70. The effects of rD-7 were independent of any residual endotoxin. Unexpectedly, these effects of rD-7 were also independent of its ability to bind to CEACAM1, as monocyte pre-treatment with the anti-CEACAM antibody A0115 known to inhibit rD-7 binding to the receptor, did not affect rD-7-driven differentiation. Further, another control protein rD-7/D (a mutant form of rD-7, known not to bind to CEACAMs), also behaved as the parent molecule. Our data suggest that specific regions of M. catarrhalis adhesin UspA1 may modulate inflammation during infection through a yet unknown receptor on monocytes.


Subject(s)
Bacterial Outer Membrane Proteins/chemistry , Cell Differentiation/drug effects , Monocytes/cytology , Moraxella catarrhalis/metabolism , Recombinant Proteins/pharmacology , Antibodies, Bacterial/metabolism , Antigens, CD/metabolism , Cell Adhesion/drug effects , Cell Adhesion Molecules/metabolism , Chemokines/metabolism , Fluorescence , Humans , Lectins, C-Type/metabolism , Lipopolysaccharide Receptors/metabolism , Mannose Receptor , Mannose-Binding Lectins/metabolism , Monocytes/drug effects , Monocytes/metabolism , Phenotype , Receptors, Cell Surface/metabolism , Reproducibility of Results
20.
PLoS One ; 7(9): e45452, 2012.
Article in English | MEDLINE | ID: mdl-23049802

ABSTRACT

Moraxella catarrhalis (Mx) is a common cause of otitis media and exacerbation of chronic obstructive pulmonary disease, an increasing worldwide problem. Surface proteins UspA1 and UspA2 of Mx bind to a number of human receptors and may function in pathogenesis. Genetic recombination events in the pathogen can generate hybrid proteins termed UspA2H. However, whether certain key functions (e.g. UspA1-specific CEACAM binding) can be exchanged between these adhesin families remains unknown. In this study, we have shown that Mx can incorporate the UspA1 CEACAM1-binding region not only into rare UspA1 proteins devoid of CEACAM-binding ability, but also into UspA2 which normally lack this capacity. Further, a screen of Mx isolates revealed the presence of novel UspA2 Variant proteins (UspA2V) in ∼14% of the CEACAM-binding population. We demonstrate that the expression of UspA2/2V with the CEACAM-binding domain enable Mx to bind both to cell surface CEACAMs and to integrins, the latter via vitronectin. Such properties of UspA2/2V have not been reported to date. The studies demonstrate that the UspA family is much more heterogeneous than previously believed and illustrate the in vivo potential for exchange of functional regions between UspA proteins which could convey novel adhesive functions whilst enhancing immune evasion.


Subject(s)
Antigens, CD/genetics , Bacterial Outer Membrane Proteins/genetics , Cell Adhesion Molecules/genetics , Moraxella catarrhalis/genetics , Mutant Chimeric Proteins/genetics , Amino Acid Sequence , Antigens, CD/metabolism , Bacterial Outer Membrane Proteins/classification , Bacterial Outer Membrane Proteins/isolation & purification , Bacterial Outer Membrane Proteins/metabolism , Cell Adhesion , Cell Adhesion Molecules/metabolism , Cell Line, Tumor , Humans , Integrins/genetics , Integrins/metabolism , Molecular Sequence Data , Moraxella catarrhalis/isolation & purification , Moraxella catarrhalis/metabolism , Moraxellaceae Infections/microbiology , Mutant Chimeric Proteins/isolation & purification , Mutant Chimeric Proteins/metabolism , Otitis Media/microbiology , Phylogeny , Protein Binding , Protein Structure, Tertiary , Pulmonary Disease, Chronic Obstructive/microbiology , Recombination, Genetic , Sequence Alignment , Transformation, Bacterial , Vitronectin/genetics , Vitronectin/metabolism
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