Biology subjects

Green, L. R.

Publications and source records attributed to Green, L. R..

8 recordsLinked to original sources

bioRxiv2026

Emergence of short-lived meningococci causing focal epidemics can be associated with gene transfer from carriage-associated Neisseria

In March 2026, an unusually large outbreak of invasive meningococcal disease (IMD) in Kent, UK, was linked to attendance at one nightclub over a single weekend. The outbreak organism was a Neisseria meningitidis variant belonging to the longstanding hyperinvasive genotype, cc41/44. Using genome analysis of six isolates from patients, alongside >48,000 meningococcal genomes, we investigated whether the outbreak variant had acquired traits potentially contributing to the highly invasive phenotype. The six isolates were capsular group B, sequence type (ST-)485, and essentially indistinguishable, consistent with the focal nature of the outbreak. Compared with their closest available relatives, we found changes mediated by phase variation, nucleotide variation, and horizontal gene transfer (HGT) involving adhesins, iron-acquisition systems (including Transferrin and Lactoferrin binding proteins, and FetA), and Type IV pili (Tfp), factors which affect bacteria-bacteria and bacteria-host interactions. These changes occurred in a ST-485 sub-lineage that expressed capsule at high levels and a PorA porin with a truncated surface-exposed epitope, both of which are predicted to reduce immune recognition. Donors for the HGT events were predominantly carriage-associated N. meningitidis and Neisseria cinerea. We show that meningococcal variants responsible for previous focal outbreaks have not been seen subsequently. We propose that focal outbreaks of IMD are caused by meningococcal variants that may have acquired traits from non- or less invasive organisms, but subsequently these variants disappear, as their highly invasive phenotype is inconsistent with sustained transmission. Ongoing disease surveillance alongside carriage studies are therefore essential to inform public health risk and manage epidemic IMD.

genomics↗

bioRxiv2026

Molecular analysis of Lancefield group C/G streptococci causing human infections in Sheffield, UK.

Lancefield group C/G streptococci (GCS/GGS) are increasingly recognised as significant human pathogens that cause a disease spectrum similar to Streptococcus pyogenes. Despite their high clinical burden in the UK, their genomic diversity remains poorly understood. We performed whole-genome sequencing (WGS) on a prospective collection of 109 consecutive GCS/GGS isolates from all infection types in Sheffield, UK, over five months in 2020. Streptococcus dysgalactiae subsp. equisimilis (SDSE) accounted for 104 isolates, while five were identified as Streptococcus canis. The SDSE population was highly diverse, comprising 15 genomic clusters and 38 unique emm-ST combinations. We identified the presence of the ST20/stG62647 international lineage (24% of isolates), a cluster globally associated with severe invasive disease. Antimicrobial resistance genes were prevalent (49%), predominantly linked to mobile genetic elements carrying tetracycline and macrolide resistance. Furthermore, a variation in the penicillin-binding protein PBP2X (P601L) was linked to reduced penicillin sensitivity (MIC 0.03 mg/L). There were few or no genetic changes in isolates obtained from the same patient, even when they were collected 8-10 weeks apart, indicating long-term persistence within a host. The unexpected detection of S. canis in human infections and the high diversity of SDSE, persistence and virulence-associated regions underscore the need for enhanced national genomic surveillance to track emerging virulent and antibiotic-resistant SDSE lineages. Impact statementLancefield group C and G streptococci, most often the species Streptococcus dysgalactiae subsp. equisimilis (SDSE), are an increasingly significant human pathogen, often mirroring the severity of infections caused by Lancefield group A Streptococcus (S. pyogenes). Despite its clinical importance, we know little about the population of SDSE circulating in the UK. This study provides the first comprehensive genomic analysis of SDSE isolates from a single UK region, identifying a highly diverse population comprising 15 distinct genomic clusters but with evidence of long-term persistence within a single host. Notably, we confirm the presence of the international stG62647/ST20 lineage in the UK, which is globally associated with severe invasive disease. Our findings also reveal a high prevalence of antimicrobial resistance genes ([~]49%), primarily linked to mobile genetic elements, and the presence of a specific variation in the penicillin-binding protein PBP2X that reduces penicillin sensitivity. Additionally, the unexpected detection of S. canis in human infections rather than animals highlights a need for monitoring. By defining the UKs SDSE population structure and its resistance landscape, this research underscores the critical need for enhanced national genomic surveillance to track emerging high-virulence and antibiotic-resistant lineages Data summarySequence files for isolates from Sheffield used for this study have been uploaded to the sequence read archive with project accession number PRJNA1333937 and accession numbers provided in Supplementary Dataset 1. The completed genome for SDE096 been deposited on GenBank with the accession number JBSXMJ000000000.

microbiology↗

bioRxiv2025

Simple Sequence Repeats Mediate Phase Variation of the Mucoid Phenotype in Hypervirulent Klebsiella pneumoniae

Hypervirulent Klebsiella pneumoniae (HVKp) express a thick mucoid capsular polysaccharide which is essential for virulence and survival in the bloodstream but inhibits epithelial adhesion and invasion. The molecular mechanisms regulating capsule expression to rapidly adapt to these distinct niches are unknown. Here, we show that high frequency mutations in a poly-G repeat in the regulator of mucoid phenotype gene, rmpA, mediates reversible ON/OFF phase variation of the mucoid phenotype. We find that these mutations generate subpopulations of bacteria with reduced capsule expression and mucoidy. In vitro and in vivo infection models reveal that phase variation to the OFF state facilitates epithelial cell infection while ON switching enhances resistance to the bactericidal activity of human serum and systemic spread to the liver and spleen in a murine infection model. Genomic analysis reveals that the phase variation mechanism is a conserved feature of all HVKp and that additional novel DNA repeats in rmpD and rmpC drive different combinations of capsule mucoidy and hyperexpression phenotypes. These findings establish a mechanistic basis for how HVKp occupy such a diverse array of niches during infection, with important implications for the design and implementation of Kp-specific vaccines and therapies.

microbiology↗

bioRxiv2024

Dynamics of the CD9 interactome during bacterial infection of epithelial cells by proximity labelling proteomics

Epithelial colonisation is often a critical first step in bacterial pathogenesis, however, different bacterial species utilise several different receptors at the cell membrane to adhere to cells. We have previously demonstrated that interference of the human tetraspanin, CD9, can reduce adherence of multiple species of bacteria to epithelial cells by approximately 50%. However, CD9 does not act as a receptor and is responsible for organising and clustering partner proteins commandeered by bacteria for efficient adherence. CD9 can organise numerous host proteins at the cell membrane but the full interactome has not been delineated. Here, using a novel CD9 proximity-labelling model, we demonstrate a vast and diverse CD9 interactome with 845 significantly enriched proteins associated with CD9 over four hours. These putative proximal proteins were associated with various cellular pathways including cell adhesion, ECM-receptor interactions, endocytosis, SNARE interactions and adherens and tight junctions. Significant and known interactors of CD9 were enriched including {beta}1 integrins and major immunoglobulin superfamily members but also included several known bacterial adherence receptors including CD44, CD46 and CD147. We further demonstrate dynamism of the interactome during infection at three separate time points with two different bacterial species, Neisseria meningitidis and Staphylococcus aureus. During meningococcal infection, 13 unique proximal proteins associated with CD9 were significantly enriched across four hours compared to uninfected cells. However, upon staphylococcal infection far fewer enriched proximal proteins were identified demonstrating that different bacteria require different host factors during CD9-mediated bacterial adherence. Transient knockdown of CD44 and CD147, candidate receptor proteins identified in our screen, significantly reduced staphylococcal and meningococcal adherence respectively. This effect was ablated in the absence of CD9 or if epithelial cells were treated with a CD9-derived peptide demonstrating the association of these proteins during staphylococcal and meningococcal adherence. We demonstrate for the first time the CD9 interactome of epithelial cells and that bacteria hijack these interactions to efficiently adhere to epithelial cells. This process is bacterial species specific, recruiting several different proteins during infection but a host-derived peptide is able to interfere with this process. We have therefore developed a tool that can measure changes within the CD9 interactome after cellular challenge, established a mechanism in which CD9 is used as a universal organiser of bacterial adhesion platforms and demonstrated that this process can be stopped using a CD9-derived peptide.

microbiology↗

bioRxiv2023

CD9 co-operation with syndecan-1 is required for a major staphylococcal adhesion pathway

ObjectivesEpithelial colonisation is a critical first step in bacterial pathogenesis. Staphylococcus aureus can utilise several host factors to associate with cells, including 5{beta}l integrin and heparan sulphate proteoglycans, such as the syndecans. Here, we demonstrate that a partner protein of both integrins and syndecans, the host membrane adapter protein tetraspanin CD9, is essential for syndecan-mediated staphylococcal adhesion. Fibronectin is also essential in this process while integrins are only critical for post-adhesion entry into human epithelial cells. Methods and ResultsTreatment of epithelial cells with CD9-derived peptide or heparin caused significant reductions in staphylococcal adherence, dependent on both CD9 and syndecan-1. Exogenous fibronectin caused a CD9-dependent increase in staphylococcal adhesion whereas blockade of {beta}1 integrins did not affect adhesion but did reduce the subsequent internalisation of adhered bacteria. CD9 disruption or deletion increased {beta}1 integrin-mediated internalisation, suggesting that CD9 coordinates sequential staphylococcal adhesion and internalisation. ConclusionsCD9 controls staphylococcal adhesion through syndecan-1, using a mechanism that likely requires CD9-mediated syndecan organisation to correctly display fibronectin at the host cell surface. We propose that CD9-derived peptides or heparin analogues could be developed as anti-adhesion treatments to inhibit the initial stages of staphylococcal pathogenesis.

microbiology↗

bioRxiv2021

Altered Sub-Genomic RNA Expression in SARS-CoV-2 B.1.1.7 Infections

SARS-CoV-2 lineage B.1.1.7 viruses are more transmissible, may lead to greater clinical severity, and result in modest reductions in antibody neutralization. subgenomic RNA (sgRNA) is produced by discontinuous transcription of the SARS-CoV-2 genome and is a crucial step in the SARS-CoV-2 life cycle. Applying our tool (periscope) to ARTIC Network Oxford Nanopore genomic sequencing data from 4400 SARS-CoV-2 positive clinical samples, we show that normalised sgRNA expression profiles are significantly increased in B.1.1.7 infections (n=879). This increase is seen over the previous dominant circulating lineage in the UK, B.1.177 (n=943), which is independent of genomic reads, E gene cycle threshold and days since symptom onset at sampling. A noncanonical sgRNA which could represent ORF9b is found in 98.4% of B.1.1.7 SARS-CoV-2 infections compared with only 13.8% of other lineages, with a 16-fold increase in median expression. We hypothesise that this is a direct consequence of a triple nucleotide mutation in nucleocapsid (28280:GAT>CAT, D3L) creating a transcription regulatory-like sequence complementary to a region 3 of the genomic leader. These findings provide a unique insight into the biology of B.1.1.7 and support monitoring of sgRNA profiles in sequence data to evaluate emerging potential variants of concern. One Sentence SummaryThe recently emerged and more transmissible SARS-CoV-2 lineage B.1.1.7 shows greater subgenomic RNA expression in clinical infections and enhanced expression of a noncanonical subgenomic RNA near ORF9b.

genomics↗

bioRxiv2020

periscope: sub-genomic RNA identification in SARS-CoV-2 ARTIC Network Nanopore Sequencing Data

We have developed periscope, a tool for the detection and quantification of sub-genomic RNA (sgRNA) in SARS-CoV-2 genomic sequence data. The translation of the SARS-CoV-2 RNA genome for most open reading frames (ORFs) occurs via RNA intermediates termed "sub-genomic RNAs". sgRNAs are produced through discontinuous transcription which relies on homology between transcription regulatory sequences (TRS-B) upstream of the ORF start codons and that of the TRS-L which is located in the 5 UTR. TRS-L is immediately preceded by a leader sequence. This leader sequence is therefore found at the 5 end of all sgRNA. We applied periscope to 1,155 SARS-CoV-2 genomes from Sheffield, UK and validated our findings using orthogonal datasets and in vitro cell systems. Using a simple local alignment to detect reads which contain the leader sequence we were able to identify and quantify reads arising from canonical and non-canonical sgRNA. We were able to detect all canonical sgRNAs at expected abundances, with the exception of ORF10. A number of recurrent non-canonical sgRNAs are detected. We show that the results are reproducible using technical replicates and determine the optimum number of reads for sgRNA analysis. In VeroE6 ACE2+/- cell lines, periscope can detect the changes in the kinetics of sgRNA in orthogonal sequencing datasets. Finally, variants found in genomic RNA are transmitted to sgRNAs with high fidelity in most cases. This tool can be applied to all sequenced COVID-19 samples worldwide to provide comprehensive analysis of SARS-CoV-2 sgRNA.

bioinformatics↗

bioRxiv2020

Unfractionated heparin potently inhibits the binding of SARS-CoV-2 spike protein to a human cell line

The SARS-CoV-2 spike protein is known to bind to the receptor, ACE2, on the surface of target cells. The spike protein is processed by membrane proteases, including TMPRSS2, and either internalises or fuses directly with the cell, leading to infection. We have identified a human cell line that expresses both ACE2 and TMPRSS2, the RT4 urinary bladder transitional carcinoma, and used it to develop a proxy assay for viral interactions with host cells. A tagged recombinant form of the spike protein, containing both the S1 and S2 domains, interacted strongly with RT4 cells as determined by flow cytometry, whereas the S1 domain and the receptor binding domain (RBD) interacted weakly. S1S2 interaction was temperature dependent and increased sharply at 37{degrees}C, suggesting that processing of the intact spike protein is likely to be important in the interaction. S1S2 protein could associate with cells with a low dependence on ACE2 expression, while RBD required the presence of ACE2 for interaction. As the spike protein has previously been shown to bind heparin, a soluble glycosaminoglycan, we used a flow cytometric assay to determine the effect of heparin on spike protein interaction with RT4 cells. Unfractionated heparin inhibited spike protein interaction with an IC50 value of <0.05U/ml whereas two low molecular weight heparins were much less effective. A mutant form of the spike protein, lacking the Arg-rich region proposed to be a furin cleavage site, interacted very weakly with cells and had a lower affinity for unfractionated and lower molecular weight heparin than the wild type spike protein. This indicates that the furin cleavage site might also be a heparin binding site and potentially important in interactions with host cells. Taken together, our data suggest that heparin, particularly unfractionated forms, could be considered to reduce clinical manifestations of COVID-19 by inhibiting continuing viral infection. Author SummarySince the emergence of SARS-CoV-2 in 2019, the world has faced a vast public health crisis. SARS-CoV-2 associates with human cells through interaction of the viral spike protein with the host receptor, ACE2. In the absence of a vaccine, new treatments are required to reduce the morbidity and mortality of SARS-CoV-2. Here, we use a novel technique to demonstrate spike protein interactions with human cells with low levels of ACE2 at the cell surface, suggesting a secondary receptor. We demonstrate the importance of a new heparin-binding site within the viral spike protein for these interactions. We also found that unfractionated heparin was able to bind to the viral spike protein and therefore, potently inhibit viral spike protein interactions with human cells. Our data demonstrate that ACE2 is not absolutely required for spike protein interactions with human cells and furthermore, that unfractionated heparin should be considered as a treatment to reduce SARS-CoV-2 viral infection.

microbiology↗