Publications
23 results found
Arredondo-Alonso S, Blundell-Hunter G, Fu Z, et al., 2023, Evolutionary and functional history of the Escherichia coli K1 capsule, Nature Communications, Vol: 14, Pages: 1-17, ISSN: 2041-1723
Escherichia coli is a leading cause of invasive bacterial infections in humans. Capsule polysaccharide has an important role in bacterial pathogenesis, and the K1 capsule has been firmly established as one of the most potent capsule types in E. coli through its association with severe infections. However, little is known about its distribution, evolution and functions across the E. coli phylogeny, which is fundamental to elucidating its role in the expansion of successful lineages. Using systematic surveys of invasive E. coli isolates, we show that the K1-cps locus is present in a quarter of bloodstream infection isolates and has emerged in at least four different extraintestinal pathogenic E. coli (ExPEC) phylogroups independently in the last 500 years. Phenotypic assessment demonstrates that K1 capsule synthesis enhances E. coli survival in human serum independent of genetic background, and that therapeutic targeting of the K1 capsule re-sensitizes E. coli from distinct genetic backgrounds to human serum. Our study highlights that assessing the evolutionary and functional properties of bacterial virulence factors at population levels is important to better monitor and predict the emergence of virulent clones, and to also inform therapies and preventive medicine to effectively control bacterial infections whilst significantly lowering antibiotic usage.
Catton EA, Bonsor DA, Herrera C, et al., 2023, Author Correction: Human CEACAM1 is targeted by a Streptococcus pyogenes adhesin implicated in puerperal sepsis pathogenesis., Nat Commun, Vol: 14
Catton EA, Bonsor DA, Herrera C, et al., 2023, Human CEACAM1 is targeted by a Streptococcus pyogenes adhesin implicated in puerperal sepsis pathogenesis, Nature Communications, Vol: 14, Pages: 1-16, ISSN: 2041-1723
Life-threatening bacterial infections in women after childbirth, known as puerperal sepsis, resulted in classical epidemics and remain a global health problem. While outbreaks of puerperal sepsis have been ascribed to Streptococcus pyogenes, little is known about disease mechanisms. Here, we show that the bacterial R28 protein, which is epidemiologically associated with outbreaks of puerperal sepsis, specifically targets the human receptor CEACAM1. This interaction triggers events that would favor development of puerperal sepsis, including adhesion to cervical cells, suppression of epithelial wound repair and subversion of innate immune responses. High-resolution structural analysis showed that an R28 domain with IgI3-like fold binds to the N-terminal domain of CEACAM1. Together, these findings demonstrate that a single adhesin-receptor interaction can drive the pathogenesis of bacterial sepsis and provide molecular insights into the pathogenesis of one of the most important infectious diseases in medical history.
Xu X, Marffy ALL, Keightley A, et al., 2022, Group B <i>Streptococcus</i> Surface Protein β: Structural Characterization of a Complement Factor H-Binding Motif and Its Contribution to Immune Evasion, JOURNAL OF IMMUNOLOGY, Vol: 208, Pages: 1232-1247, ISSN: 0022-1767
McCarthy AJ, Taylor PW, 2022, Analysis of Escherichia coli K1 Virulence Genes by Transposon-Directed Sequencing., Methods Mol Biol, Vol: 2377, Pages: 199-213
Transposon-directed insertion site sequencing (TraDIS) combines random transposon mutagenesis and massively parallel sequencing to shed light on bacterial gene function on a genome-wide scale and in a high-throughput manner. The technique has proven to be successful in the determination of the fitness contribution of every gene under specific conditions both in vitro and in vivo. In this contribution, we describe the procedure used for the identification of Escherichia coli K1 genes essential for in vitro growth, survival in pooled human serum and gastrointestinal colonisation in a rodent model of neonatal invasive infection. TraDIS has broad application for systems-level analysis of a wide range of pathogenic, commensular and saprophytic bacteria.
van Sorge NM, Bonsor DA, Deng L, et al., 2021, Bacterial protein domains with a novel Ig-like fold target human CEACAM receptors, The EMBO Journal, Vol: 40, Pages: 1-20, ISSN: 0261-4189
Streptococcus agalactiae, also known as group B Streptococcus (GBS), is the major cause of neonatal sepsis in humans. A critical step to infection is adhesion of bacteria to epithelial surfaces. GBS adhesins have been identified to bind extracellular matrix components and cellular receptors. However, several putative adhesins have no host binding partner characterised. We report here that surface-expressed β protein of GBS binds to human CEACAM1 and CEACAM5 receptors. A crystal structure of the complex showed that an IgSF domain in β represents a novel Ig-fold subtype called IgI3, in which unique features allow binding to CEACAM1. Bioinformatic assessment revealed that this newly identified IgI3 fold is not exclusively present in GBS but is predicted to be present in adhesins from other clinically important human pathogens. In agreement with this prediction, we found that CEACAM1 binds to an IgI3 domain found in an adhesin from a different streptococcal species. Overall, our results indicate that the IgI3 fold could provide a broadly applied mechanism for bacteria to target CEACAMs.
Frosini SM, Bond R, McCarthy AJ, et al., 2020, Genes on the Move: In Vitro Transduction of Antimicrobial Resistance Genes between Human and Canine Staphylococcal Pathogens, MICROORGANISMS, Vol: 8
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- Citations: 12
Lewis Marffy A, McCarthy A, 2020, Leukocyte immunoglobulin-like receptors (LILRs) on human neutrophils: modulators of infection and immunity, Frontiers in Immunology, Vol: 11, ISSN: 1664-3224
Neutrophils have a crucial role in defense against microbes. Immune receptors allow neutrophils to sense their environment, with many receptors functioning to recognize signs of infection and to promote antimicrobial effector functions. However, the neutrophil response must be tightly regulated to prevent excessive inflammation and tissue damage, and regulation is achieved by expression of inhibitory receptors that can raise activation thresholds. The leukocyte immunoglobulin-like receptor (LILR) family contain activating and inhibitory members that can up- or down-regulate immune cell activity. New ligands and functions for LILR continue to emerge. Understanding the role of LILR in neutrophil biology is of general interest as they can activate and suppress antimicrobial responses of neutrophils and because several human pathogens exploit these receptors for immune evasion. This review focuses on the role of LILR in neutrophil biology. We focus on the current knowledge of LILR expression on neutrophils, the known functions of LILR on neutrophils, and how these receptors may contribute to shaping neutrophil responses during infection.
Xu X, van Sorge N, van der Lans S, et al., 2020, Structural and Interaction Insight in <it>Streptococcal</it> beta C Proteins, Annual Meeting on Experimental Biology, Publisher: WILEY, ISSN: 0892-6638
Zhao Y, van Woudenbergh E, Zhu J, et al., 2020, The Orphan Immune Receptor LILRB3 Modulates Fc Receptor-Mediated Functions of Neutrophils, JOURNAL OF IMMUNOLOGY, Vol: 204, Pages: 954-966, ISSN: 0022-1767
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- Citations: 15
McCarthy AJ, Birchenough GMH, Taylor PW, 2019, Loss of Trefoil Factor 2 Sensitizes Rat Pups to Systemic Infection with the Neonatal Pathogen Escherichia coli K1, Infection and Immunity, Vol: 87, ISSN: 0019-9567
<jats:title>ABSTRACT</jats:title><jats:p>Gastrointestinal (GI) colonization of 2-day-old (P2) rat pups with <jats:named-content content-type="genus-species">Escherichia coli</jats:named-content> K1 results in translocation of the colonizing bacteria across the small intestine, bacteremia, and invasion of the meninges, with animals frequently succumbing to lethal infection. Infection, but not colonization, is strongly age dependent; pups become progressively less susceptible to infection over the P2-to-P9 period. Colonization leads to strong downregulation of the gene encoding trefoil factor 2 (Tff2), preventing maturation of the protective mucus barrier in the small intestine. Trefoil factors promote mucosal homeostasis. We investigated the contribution of Tff2 to protection of the neonatal rat from <jats:named-content content-type="genus-species">E. coli</jats:named-content> K1 bacteremia and tissue invasion. Deletion of <jats:italic>tff2</jats:italic>, using clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9, sensitized P9 pups to <jats:named-content content-type="genus-species">E. coli</jats:named-content> K1 bacteremia. There were no differences between <jats:italic>tff2<jats:sup>−/</jats:sup></jats:italic><jats:sup>−</jats:sup> homozygotes and the wild type with regard to the dynamics of GI colonization. Loss of the capacity to elaborate Tff2 did not impact GI tract integrity or the thickness of the small-intestinal mucus layer but, in contrast to P9 wild-type pups, enabled <jats:named-content content-type="genus-species">E. coli</jats:named-content> K1 bacteria to gain access to epithelial surfaces in the distal region of the small intestine and exploit an intracellular route across the epithelial monolayer to enter the blood circulation via the mesenteric lymphatic system. Al
Koymans KJ, Feitsma LJ, Bisschop A, et al., 2018, Molecular basis determining species specificity for TLR2 inhibition by staphylococcal superantigen-like protein 3 (SSL3), Veterinary Research, Vol: 49, ISSN: 0928-4249
Staphylococcus aureus is a versatile opportunistic pathogen, causing disease in human and animal species. Its pathogenicity is linked to the ability of S. aureus to secrete immunomodulatory molecules. These evasion proteins bind to host receptors or their ligands, resulting in inhibitory effects through high affinity protein–protein interactions. Staphylococcal evasion molecules are often species-specific due to differences in host target proteins between species. We recently solved the crystal structure of murine TLR2 in complex with immunomodulatory molecule staphylococcal superantigen-like protein 3 (SSL3), which revealed the essential residues within SSL3 for TLR2 inhibition. In this study we aimed to investigate the molecular basis of the interaction on the TLR2 side. The SSL3 binding region on murine TLR2 was compared to that of other species through sequence alignment and homology modeling, which identified interspecies differences. To examine whether this resulted in altered SSL3 activity on the corresponding TLR2s, bovine, equine, human, and murine TLR2 were stably expressed in HEK293T cells and the ability of SSL3 to inhibit TLR2 was assessed. We found that SSL3 was unable to inhibit bovine TLR2. Subsequent loss and gain of function mutagenesis showed that the lack of inhibition is explained by the absence of two tyrosine residues in bovine TLR2 that play a prominent role in the SSL3–TLR2 interface. We found no evidence for the existence of allelic SSL3 variants that have adapted to the bovine host. Thus, within this paper we reveal the molecular determinants of the TLR2–SSL3 interaction which adds to our understanding of staphylococcal host specificity.
McCarthy AJ, Stabler RA, Taylor PW, 2018, Genome-Wide Identification by Transposon Insertion Sequencing of Escherichia coli K1 Genes Essential for In Vitro Growth, Gastrointestinal Colonizing Capacity, and Survival in Serum, Journal of Bacteriology, Vol: 200, ISSN: 0021-9193
<jats:title>ABSTRACT</jats:title> <jats:p> <jats:named-content content-type="genus-species">Escherichia coli</jats:named-content> K1 strains are major causative agents of invasive disease of newborn infants. The age dependency of infection can be reproduced in neonatal rats. Colonization of the small intestine following oral administration of K1 bacteria leads rapidly to invasion of the blood circulation; bacteria that avoid capture by the mesenteric lymphatic system and evade antibacterial mechanisms in the blood may disseminate to cause organ-specific infections such as meningitis. Some <jats:named-content content-type="genus-species">E. coli</jats:named-content> K1 surface constituents, in particular the polysialic acid capsule, are known to contribute to invasive potential, but a comprehensive picture of the factors that determine the fully virulent phenotype has not emerged so far. We constructed a library and constituent sublibraries of ∼775,000 Tn <jats:italic>5</jats:italic> transposon mutants of <jats:named-content content-type="genus-species">E. coli</jats:named-content> K1 strain A192PP and employed transposon-directed insertion site sequencing (TraDIS) to identify genes required for fitness for infection of 2-day-old rats. Transposon insertions were lacking in 357 genes following recovery on selective agar; these genes were considered essential for growth in nutrient-replete medium. Colonization of the midsection of the small intestine was facilitated by 167 <jats:named-content content-type="genus-species">E. coli</jats:named-content> K1 gene products. Restricted bacterial translocation across epithelial barriers precluded TraDIS
de Jong NWM, Ramyar KX, Guerra FE, et al., 2017, Immune evasion by a staphylococcal inhibitor of myeloperoxidase, Proceedings of the National Academy of Sciences, Vol: 114, Pages: 9439-9444, ISSN: 0027-8424
Staphylococcus aureus is highly adapted to its host and has evolved many strategies to resist opsonization and phagocytosis. Even after uptake by neutrophils, S. aureus shows resistance to killing, which suggests the presence of phagosomal immune evasion molecules. With the aid of secretome phage display, we identified a highly conserved protein that specifically binds and inhibits human myeloperoxidase (MPO), a major player in the oxidative defense of neutrophils. We have named this protein “staphylococcal peroxidase inhibitor” (SPIN). To gain insight into inhibition of MPO by SPIN, we solved the cocrystal structure of SPIN bound to a recombinant form of human MPO at 2.4-Å resolution. This structure reveals that SPIN acts as a molecular plug that prevents H2O2 substrate access to the MPO active site. In subsequent experiments, we observed that SPIN expression increases inside the neutrophil phagosome, where MPO is located, compared with outside the neutrophil. Moreover, bacteria with a deleted gene encoding SPIN showed decreased survival compared with WT bacteria after phagocytosis by neutrophils. Taken together, our results demonstrate that S. aureus secretes a unique proteinaceous MPO inhibitor to enhance survival by interfering with MPO-mediated killing.
Birchenough GMH, Dalgakiran F, Witcomb LA, et al., 2017, Postnatal development of the small intestinal mucosa drives age-dependent, regio-selective susceptibility to Escherichia coli K1 infection, Scientific Reports, Vol: 7, ISSN: 2045-2322
The strong age dependency of neonatal systemic infection with Escherichia coli K1 can be replicated in the neonatal rat. Gastrointestinal (GI) colonization of two-day-old (P2) rats leads to invasion of the blood within 48 h of initiation of colonization; pups become progressively less susceptible to infection over the P2-P9 period. We show that, in animals colonized at P2 but not at P9, E. coli K1 bacteria gain access to the enterocyte surface in the mid-region of the small intestine and translocate through the epithelial cell monolayer by an intracellular pathway to the submucosa. In this region of the GI tract, the protective mucus barrier is poorly developed but matures to full thickness over P2-P9, coincident with the development of resistance to invasion. At P9, E. coli K1 bacteria are physically separated from villi by the mucus layer and their numbers controlled by mucus-embedded antimicrobial peptides, preventing invasion of host tissues.
McCarthy AJ, Negus D, Martin P, et al., 2016, Pathoadaptive Mutations of Escherichia coli K1 in Experimental Neonatal Systemic Infection, PLOS ONE, Vol: 11, Pages: e0166793-e0166793
Garcie C, Tronnet S, Garénaux A, et al., 2016, The Bacterial Stress-Responsive Hsp90 Chaperone (HtpG) Is Required for the Production of the Genotoxin Colibactin and the Siderophore Yersiniabactin inEscherichia coli, Journal of Infectious Diseases, Vol: 214, Pages: 916-924, ISSN: 0022-1899
Witcomb LA, Collins JW, McCarthy AJ, et al., 2015, Bioluminescent Imaging Reveals Novel Patterns of Colonization and Invasion in Systemic Escherichia coli K1 Experimental Infection in the Neonatal Rat, Infection and Immunity, Vol: 83, Pages: 4528-4540, ISSN: 0019-9567
Key features of Escherichia coli K1-mediated neonatal sepsis and meningitis, such as a strong age dependency and development along the gut-mesentery-blood-brain course of infection, can be replicated in the newborn rat. We examined temporal and spatial aspects of E. coli K1 infection following initiation of gastrointestinal colonization in 2-day-old (P2) rats after oral administration of E. coli K1 strain A192PP and a virulent bioluminescent derivative, E. coli A192PP-lux2. A combination of bacterial enumeration in the major organs, two-dimensional bioluminescence imaging, and three-dimensional diffuse light imaging tomography with integrated micro-computed tomography indicated multiple sites of colonization within the alimentary canal; these included the tongue, esophagus, and stomach in addition to the small intestine and colon. After invasion of the blood compartment, the bacteria entered the central nervous system, with restricted colonization of the brain, and also invaded the major organs, in line with increases in the severity of symptoms of infection. Both keratinized and nonkeratinized surfaces of esophagi were colonized to a considerably greater extent in susceptible P2 neonates than in corresponding tissues from infection-resistant 9-day-old rat pups; the bacteria appeared to damage and penetrate the nonkeratinized esophageal epithelium of infection-susceptible P2 animals, suggesting the esophagus represents a portal of entry for E. coli K1 into the systemic circulation. Thus, multimodality imaging of experimental systemic infections in real time indicates complex dynamic patterns of colonization and dissemination that provide new insights into the E. coli K1 infection of the neonatal rat.
McCarthy AJ, Martin P, Cloup E, et al., 2015, The Genotoxin Colibactin Is a Determinant of Virulence in Escherichia coli K1 Experimental Neonatal Systemic Infection, Infection and Immunity, Vol: 83, Pages: 3704-3711, ISSN: 0019-9567
<jats:title>ABSTRACT</jats:title> <jats:p> <jats:named-content content-type="genus-species">Escherichia coli</jats:named-content> strains expressing the K1 capsule are a major cause of sepsis and meningitis in human neonates. The development of these diseases is dependent on the expression of a range of virulence factors, many of which remain uncharacterized. Here, we show that all but 1 of 34 <jats:named-content content-type="genus-species">E. coli</jats:named-content> K1 neonatal isolates carried <jats:italic>clbA</jats:italic> and <jats:italic>clbP</jats:italic> , genes contained within the <jats:italic>pks</jats:italic> pathogenicity island and required for the synthesis of colibactin, a polyketide-peptide genotoxin that causes genomic instability in eukaryotic cells by induction of double-strand breaks in DNA. Inactivation of <jats:italic>clbA</jats:italic> and <jats:italic>clbP</jats:italic> in <jats:named-content content-type="genus-species">E. coli</jats:named-content> A192PP, a virulent strain of serotype O18:K1 that colonizes the gastrointestinal tract and translocates to the blood compartment with very high frequency in experimental infection of the neonatal rat, significantly reduced the capacity of A192PP to colonize the gut, engender double-strand breaks in DNA, and cause invasive, lethal disease. Mutation of <jats:italic>clbA</jats:italic> , which encodes a pleiotropic enzyme also involved in siderophore synthesis, impacted virulence to a greater extent than mutation of <jats:italic>clbP</jats:italic> , encoding an enzyme specific to colibactin synthesis. Restor
McCarthy AJ, Harrison EM, Stanczak-Mrozek K, et al., 2015, Genomic insights into the rapid emergence and evolution of MDR in <i>Staphylococcus pseudintermedius</i>, Journal of Antimicrobial Chemotherapy, Vol: 70, Pages: 997-1007, ISSN: 0305-7453
<jats:title>Abstract</jats:title> <jats:sec> <jats:title>Objectives</jats:title> <jats:p>MDR methicillin-resistant Staphylococcus pseudintermedius (MRSP) strains have emerged rapidly as major canine pathogens and present serious treatment issues and concerns to public health due to their, albeit low, zoonotic potential. A further understanding of the genetics of resistance arising from a broadly susceptible background of S. pseudintermedius is needed.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>We sequenced the genomes of 12 S. pseudintermedius isolates of varied STs and resistance phenotypes.</jats:p> </jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>Nine distinct clonal lineages had acquired either staphylococcal cassette chromosome (SCC) mec elements and/or Tn5405-like elements carrying up to five resistance genes [aphA3, sat, aadE, erm(B), dfrG] to generate MRSP, MDR methicillin-susceptible S. pseudintermedius and MDR MRSP populations. The most successful and clinically problematic MDR MRSP clones, ST68 SCCmecV(T) and ST71 SCCmecII-III, have further accumulated mutations in gyrA and grlA conferring resistance to fluoroquinolones. The carriage of additional mobile genetic elements (MGEs) was highly variable, suggesting that horizontal gene transfer is frequent in S. pseudintermedius populations.</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Importantly, the data suggest that MDR MRSP evolved rapidly by the acquisition of a very limited number of MGEs and mutations, and that the use of many classes of antimicrobials may
Garnett JP, Braun D, McCarthy AJ, et al., 2014, Fructose transport-deficient Staphylococcus aureus reveals important role of epithelial glucose transporters in limiting sugar-driven bacterial growth in airway surface liquid, Cellular and Molecular Life Sciences, Vol: 71, Pages: 4665-4673, ISSN: 1420-682X
Dalgakiran F, Witcomb LA, McCarthy AJ, et al., 2014, Non-Invasive Model of Neuropathogenic <em>Escherichia coli</em> Infection in the Neonatal Rat, Journal of Visualized Experiments
McCarthy AJ, Loeffler A, Witney AA, et al., 2014, Extensive Horizontal Gene Transfer during Staphylococcus aureus Co-colonization In Vivo, Genome Biology and Evolution, Vol: 6, Pages: 2697-2708
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