Professor Graham Stewart

Head of the Department of Microbial Sciences
+44 (0)1483 686423
15 AX 02


University roles and responsibilities

  • Bacteriology Section Leader
  • Chair Board of Examinations
  • Professor of Molecular Bacteriology

    Business, industry and community links


    Research interests

    Research projects

    Research collaborations



    G. Michael Taylor, Katie White-Iribhogbe, Garrard Cole, David Ashby, Graham R Stewart, Heidi Dawson-Hobbis (2024)Bioarchaeological investigation of individuals with suspected multibacillary leprosy from the mediaeval leprosarium of St Mary Magdalen, Winchester, Hampshire, UK, In: Journal of medical microbiology73(2)

    Introduction. We have examined four burials from the St Mary Magdalen mediaeval leprosarium cemetery in Winchester, Hampshire, UK. One (Sk.8) was a male child, two (Sk.45 and Sk.52) were adolescent females and the fourth (Sk.512) was an adult male. The cemetery was in use between the 10th and 12th centuries. All showed skeletal lesions of leprosy. Additionally, one of the two females (Sk.45) had lesions suggestive of multi-cystic tuberculosis and the second (Sk.52) of leprogenic odontodysplasia (LO), a rare malformation of the roots of the permanent maxillary incisors. Gap statement. Relatively little is known of the manifestations of lepromatous leprosy (LL) in younger individuals from the archaeological record. Aims and Methodology. To address this, we have used ancient DNA testing and osteological examination of the individuals, supplemented with X-ray and microcomputed tomography (micro-CT) scan as necessary to assess the disease status. Results and Conclusions. The presence of Mycobacterium leprae DNA was confirmed in both females, and genotyping showed SNP type 3I-1 strains but with a clear genotypic variation. We could not confirm Mycobacterium tuberculosis complex DNA in the female individual SK.45. High levels of M. leprae DNA were found within the pulp cavities of four maxillary teeth from the male child (Sk.8) with LO, consistent with the theory that the replication of M. leprae in alveolar bone may interfere with root formation at key stages of development. We report our biomolecular findings in these individuals and review the evidence this site has contributed to our knowledge of mediaeval leprosy.

    Louise H. Lefrançois, Jahn Nitschke, Huihai Wu, Gaël Panis, Julien Prados, Rachel E. Butler, Tom A. Mendum, Nabil Hanna, Graham R. Stewart, Thierry Soldati (2024)Temporal genome-wide fitness analysis of Mycobacterium marinum during infection reveals the genetic requirement for virulence and survival in amoebae and microglial cells, In: mSystems9(2)e0132623 American Society for Microbiology

    Tuberculosis remains the most pervasive infectious disease and the recent emergence of drug-resistant strains emphasizes the need for more efficient drug treatments. A key feature of pathogenesis, conserved between the human pathogen Mycobacterium tuberculosis and the model pathogen Mycobacterium marinum, is the metabolic switch to lipid catabolism and altered expression of virulence genes at different stages of infection. This study aims to identify genes involved in sustaining viable intracellular infection. We applied transposon sequencing (Tn-Seq) to M. marinum, an unbiased genome-wide strategy combining saturation insertional mutagenesis and high-throughput sequencing. This approach allowed us to identify the localization and relative abundance of insertions in pools of transposon mutants. Gene essentiality and fitness cost of mutations were quantitatively compared between in vitro growth and different stages of infection in two evolutionary distinct phagocytes, the amoeba Dictyostelium discoideum and the murine BV2 microglial cells. In the M. marinum genome, 57% of TA sites were disrupted and 568 genes (10.2%) were essential, which is comparable to previous Tn-Seq studies on M. tuberculosis and M. bovis. Major pathways involved in the survival of M. marinum during infection of D. discoideum are related to DNA damage repair, lipid and vitamin metabolism, the type VII secretion system (T7SS) ESX-1, and the Mce1 lipid transport system. These pathways, except Mce1 and some glycolytic enzymes, were similarly affected in BV2 cells. These differences suggest subtly distinct nutrient availability or requirement in different host cells despite the known predominant use of lipids in both amoeba and microglial cells.IMPORTANCEThe emergence of biochemically and genetically tractable host model organisms for infection studies holds the promise to accelerate the pace of discoveries related to the evolution of innate immunity and the dissection of conserved mechanisms of cell-autonomous defenses. Here, we have used the genetically and biochemically tractable infection model system Dictyostelium discoideum/Mycobacterium marinum to apply a genome-wide transposon-sequencing experimental strategy to reveal comprehensively which mutations confer a fitness advantage or disadvantage during infection and compare these to a similar experiment performed using the murine microglial BV2 cells as host for M. marinum to identify conservation of virulence pathways between hosts.

    G. Michael Taylor, Eileen M. Murphy, Tom A. Mendum, Alistair W. G. Pike, Bethan Linscott, Huihai Wu, Justin O'Grady, Hollian Richardson, Edmond O'Donovan, Carmelita Troy, Graham R. Stewart (2018)Leprosy at the edge of Europe-Biomolecular, isotopic and osteoarchaeological findings from medieval Ireland, In: PloS one13(12)e0209495 Public Library of Science

    Relatively little is known of leprosy in Medieval Ireland; as an island located at the far west of Europe it has the potential to provide interesting insights in relation to the historical epidemiology of the disease. To this end the study focuses on five cases of probable leprosy identified in human skeletal remains excavated from inhumation burials. Three of the individuals derived from the cemetery of St Michael Le Pole, Golden Lane, Dublin, while single examples were also identified from Ardreigh, Co. Kildare, and St Patrick's Church, Armoy, Co. Antrim. The individuals were radiocarbon dated and examined biomolecularly for evidence of either of the causative pathogens, M. leprae or M. lepromatosis. Oxygen and strontium isotopes were measured in tooth enamel and rib samples to determine where the individuals had spent their formative years and to ascertain if they had undertaken any recent migrations. We detected M. leprae DNA in the three Golden Lane cases but not in the probable cases from either Ardreigh Co. Kildare or Armoy, Co. Antrim. M. lepromatosis was not detected in any of the burals. DNA preservation was sufficiently robust to allow genotyping of M. leprae strains in two of the Golden Lane burials, SkCXCV (12-13th century) and SkCCXXX (11-13th century). These strains were found to belong on different lineages of the M. leprae phylogenetic tree, namely branches 3 and 2 respectively. Whole genome sequencing was also attempted on these two isolates with a view to gaining further information but poor genome coverage precluded phylogenetic analysis. Data from the biomolecular study was combined with osteological, isotopic and radiocarbon dating to provide a comprehensive and multidisciplinary study of the Irish cases. Strontium and oxygen isotopic analysis indicate that two of the individuals from Golden Lane (SkCXLVIII (10-11th century) and SkCXCV) were of Scandinavian origin, while SkCCXXX may have spent his childhood in the north of Ireland or central Britain. We propose that the Vikings were responsible for introducing leprosy to Ireland. This work adds to our knowledge of the likely origins of leprosy in Medieval Ireland and will hopefully stimulate further research into the history and spread of this ancient disease across the world.

    H. Dawson-Hobbis, G. M. Taylor, G.R. Stewart (2021)A case of childhood tuberculosis from late mediaeval Somerset, England, In: Tuberculosis128102088 Elsevier

    Background The remains of a 3-5 year-old child from the late mediaeval cemetery serving the Priory of St. Peter and St. Paul, Taunton, Somerset, UK was the subject of an aDNA study. Objective The aim was to distinguish between two differential diagnoses suggested by earlier osteological examination of the remains; either tuberculosis or Langerhans cell histiocytosis. Findings The remains tested positive for MTB complex markers, corroborating this diagnosis reached on osteological grounds. Based on positivity for the mtp40 element and a deletion in the pks15/1 locus, we conclude that infection was due to a strain of the human pathogen M. tuberculosis belonging to lineage 4. Although DNA recovered from the case was heavily fragmented, sex determination by amelogenin PCR suggested these are the remains of a young male child. The findings are discussed considering additions to the literature since the original report. Conclusions Descriptions of tuberculosis in children from this period are rare and burial Sk2077 represents the first UK example of a pre-adolescent individual to have a molecular diagnosis combined with osteological pathology. This provides an important reference of childhood tuberculosis and insight into the likely presence of tuberculosis in the mediaeval adult population served by this cemetery.

    G. Cole, G. M. Taylor, G. R. Stewart, H. Dawson-Hobbis (2022)Ancient DNA confirmation of lepromatous leprosy in a skeleton with concurrent osteosarcoma, excavated from the leprosarium of St. Mary Magdalen in Winchester, Hants., UK, In: European journal of clinical microbiology & infectious diseases41(11)pp. 1295-1304 Springer

    To establish a biological profile and disease aetiologies for one of four burials recovered during a Time Team dig at the St. Mary Magdalen leprosarium , Winchester, UK in AD 2000. Osteological techniques were applied to estimate age at death, biological sex, stature and pathology. Visual assessment of the material was supplemented by radiographic examination. Evidence for leprosy DNA was sought using ancient DNA (aDNA) analysis. The remains are those of a male individual excavated from a west–east aligned grave. The skeleton shows signs of two pathologies. Remodelling of the rhino-maxillary area and degenerative changes to small bones of the feet and reactive bone on the distal lower limbs suggest a multibacillary form of leprosy, whereas the right tibia and fibula show the presence of a primary neoplasm identified as an osteosarcoma. The aDNA study confirmed presence of Mycobacterium leprae in several skeletal elements, and the strain was genotyped to the 3I lineage, one of two main SNP types present in mediaeval Britain and ancestral to extant strains in America. This is a rare documentation of leprosy in association with a primary neoplasm.

    Wellington Owusu, Arnoud H M van Vliet, Natalie E Riddell, Graham Stewart, Winifred C Akwani, Sherihane Aryeetey, Rejoice Agyeiwaa Arthur, Augustina Angelina Sylverken, Suzanne M Hingley-Wilson (2023)A multiplex PCR assay for the differentiation of Mycobacterium tuberculosis complex reveals high rates of mixed-lineage tuberculosis infections among patients in Ghana, In: Frontiers in cellular and infection microbiology131125079 Frontiers

    In low-resource settings with high tuberculosis (TB) burdens, lack of rapid diagnostic methods for detection and differentiation of complex (MTBC) is a major challenge affecting TB management. This study utilized comparative genomic analyses of MTBC lineages; , Lineages 5/6 and to identify lineage-specific genes. Primers were designed for the development of a Multiplex PCR assay which was successful in differentiating the MTBC lineages. There was no cross-reaction with other respiratory pathogens tested. Validation of the assay using clinical samples was performed with sputum DNA extracts from 341 clinically confirmed active TB patients. It was observed that 24.9% of cases were caused by , while L5 & L6 reported 9.0% and 14.4%, respectively. infection was the least frequently detected lineage with 1.8%. Also, 27.0% and 17.0% of the cases were PCR negative and unspeciated, respectively. However, mixed-lineage TB infections were recorded at a surprising 5.9%. This multiplex PCR assay will allow speciation of MTBC lineages in low-resource regions, providing rapid differentiation of TB infections to select appropriate medication at the earliest possible time point. It will also be useful in epidemiological surveillance studies providing reliable information on the prevalence of TB lineages as well as identifying difficult to treat cases of mixed-lineage tuberculosis infections.

    Laura Hunter, Suzie Hingley-Wilson, Graham R. Stewart, Sally A. Sharpe, Francisco Javier Salguero (2022)Dynamics of Macrophage, T and B Cell Infiltration Within Pulmonary Granulomas Induced by Mycobacterium tuberculosis in Two Non-Human Primate Models of Aerosol Infection, In: Frontiers in immunology12pp. 776913-776913 Frontiers Media Sa

    Non-human primate models of Tuberculosis (TB) are one of the most commonly used within the experimental TB field because they closely mimic the whole spectrum of disease progression of human TB. However, the early cellular interactions of the pulmonary granuloma are still not well understood. The use of this model allows investigation into the early interactions of cells within pulmonary granulomas which cannot be undertaken in human samples. Pulmonary granulomas from rhesus and cynomolgus macaques from two timepoints post infection were categorised into categories 1 - 6 (early to late stage granulomas) and immunohistochemistry was used to identify CD68+ macrophages, CD3+ T cells and CD20+ B cells. Multinucleated giant cells and acid-fast bacilli were also quantified. At week four post infection, cynomolgus macaques were found to have more CD68+ cells than rhesus in all but category 1 granulomas. Cynomolgus also had a significantly higher percentage of CD20+ B cells in category 1 granulomas. At week twelve post infection, CD68+ cells were most abundant in category 4 and 5 granulomas in both species; however, there were no significant differences between them. CD3+ T cells and CD20+ B cells were significantly higher in the majority of granuloma categories in cynomolgus compared to rhesus. Multinucleated giant cells and acid-fast bacilli were most abundant in categories 5 and 6 at week 12 post challenge in both species. This study has identified the basic cellular composition and spatial distribution of immune cells within pulmonary granulomas in both rhesus and cynomolgus macaques over time. The data from this study will add to the knowledge already gained in this field and may inform future research on vaccines and therapeutics for TB.

    Jillian Maniego, Orla Giles, Pamela Hincks, Graham Stewart, Christopher Proudman, Edward Ryder (2023)Long-read sequencing assays designed to detect potential gene editing events in the myostatin gene revealed distinct haplotype signatures in the Thoroughbred horse population, In: Animal genetics54(4)pp. 470-482 Wiley

    We present here the use of targeted, long-read sequencing of the myostatin (MSTN) gene as a model to detect potential gene editing events in Thoroughbred horses. MSTN is a negative regulator of muscle development, making the gene a prime candidate target for gene doping. By sequencing the complete gene in one PCR product, we can catalogue all mutations without the need to produce short-fragment libraries. A panel of reference material fragments with defined mutations was constructed and successfully sequenced by both Oxford Nanopore and Illumina-based methods, showing that gene doping editing events can be detected using this technology. To ascertain the normal variation within the population, we sequenced the MSTN gene in 119 UK Thoroughbred horses. Variants from the reference genome were assigned to haplotypes and eight distinct patterns, designated Hap1 (reference genome) to Hap8, were determined with haplotypes Hap2 and Hap3 (which includes the 'speed gene' variant) being far the most prevalent. Hap3 was most abundant in flat-racing horses, whereas Hap2 was most abundant in jump-racing. Within this data set, results for 105 racehorses from out-of-competition sampling were compared between matrices of extracted DNA and direct PCR of whole blood from lithium heparin gel tubes, and strong agreement was found between the two methods. The direct-blood PCR was achieved without compromising the sample prior to plasma separation for analytical chemistry, and could thus be used as part of a routine screening workflow for gene editing detection.

    Jillian Maniego, Bogusia Pesko, Jocelyn Habershon-Butcher, Pamela Hincks, Polly Taylor, Teruaki Tozaki, Aoi Ohnuma, Graham Stewart, Christopher Proudman, Edward Ryder (2022)Use of mitochondrial sequencing to detect gene doping in horses via gene editing and somatic cell nuclear transfer, In: Drug testing and analysis14(8)pp. 1429-1437 Wiley

    Gene editing and subsequent cloning techniques offer great potential not only in genetic disease correction in domestic animals but also in livestock production by enhancement of desirable traits. The existence of the technology, however, leaves it open to potential misuse in performance-led sports such as horseracing and other equestrian events. Recent advances in equine gene editing, regarding the generation of gene-edited embryos using CRISPR/Cas9 technology and somatic cell nuclear transfer, have highlighted the need to develop tools to detect potential prohibited use of the technology. One possible method involves the characterisation of the mitochondrial genome (which is not routinely preserved during cloning) and comparing it with the sequence of the registered dam. We present here our approach to whole-mitochondrial sequencing using tiled long-range PCR and next-generation sequencing. To determine whether the background mutation rate in the mitochondrial genome could potentially confound results, we sequenced 10 sets of dam and foal duos. We found variation between duos but none within duos, indicating that this method is feasible for future screening systems. Analysis of WGS data from over 100 Thoroughbred horses revealed wide variation in the mitochondria sequence within the breed, further displaying the utility of this approach.

    Jillian Maniego, Bogusia Pesko, Pamela Hincks, Polly Taylor, Graham Stewart, Christopher Proudman, James Scarth, Edward Ryder (2022)Direct sequence confirmation of qPCR products for gene doping assay validation in horses, In: Drug testing and analysis14(6)pp. 1017-1025

    The misuse of gene therapy by the introduction of transgenes via plasmid or viral vectors as a doping agent is an increasing concern in human and animal sports, not only in consideration to fair competition but also in potential detrimental effects to welfare. Doping events can be detected by polymerase chain reaction (PCR) amplification of a transgene-specific region of DNA. Quantitative real-time PCR (qPCR) is particularly suited to confirmatory investigations where precise limits of detection can be calculated. To fully validate a qPCR experiment, it is highly desirable to confirm the identity of the amplicon. Although post-PCR techniques such as melt curve and fragment size analysis can provide strong evidence that the amplicon is as expected, sequence identity confirmation may be beneficial as part of regulatory proceedings. We present here our investigation into two alternative processes for the direct assessment of qPCR products for five genes using next-generation sequencing: ligation of sequence-ready adapters to qPCR products and qPCR assays performed with primers tailed with Illumina flow cell binding sites. To fully test the robustness of the techniques at concentrations required for gene doping detection, we also calculated a putative limit of detection for the assays. Both ligated adapters and tailed primers were successful in producing sequence data for the qPCR products without further amplification. Ligated adapters are preferred, however, as they do not require re-optimisation of existing qPCR assays.

    Jillian Maniego, Bogumila Pesko, Jocelyn Habershon-Butcher, Pamela Hincks, Polly Taylor, Graham Stewart, Christopher Proudman, Edward Ryder (2023)Detection of adeno-associated viral DNA in equine post-administration frozen blood and plasma samples after long-term storage, In: Drug testing and analysis Wiley

    Gene doping in horses is a threat to the fairness in sport and has serious implications for animal welfare. To investigate the effect of long-term storage on the detection of AAV in plasma and whole blood, samples from an administration study using an adeno-associated virus serotype 6 expressing green fluorescence protein (AAV6-GFP) were stored at -20 & DEG;C for 8 months before analysis. The AAV vector was detected in stored plasma samples, following the same detection profile as the fresh plasma samples. The stored blood showed lower overall DNA detection but followed the same detection profile as the plasma samples. This study provides confidence that re-analysing plasma samples and/or analysing a frozen 'B' sample with different matrix such as whole blood after prolonged storage will still result in the detection of gene doping material. Equine whole blood and plasma samples from an administration of AAV-GFP viral vector were stored at -20 & DEG;C for 8 months and analysed with qPCR and massively parallel sequencing. The vector detection in stored plasma samples followed the same detection profile as the fresh plasma samples with minimal degradation. Stored blood samples showed lower overall DNA detection but followed the same detection profile as the plasma samples. This study provides confidence in the detection of gene doping material when re-analysing samples and/or analysing 'B' samples for confirmatory analysis.image

    Diane Frances Lee, Graham Roger Stewart, Mark Andrew Chambers (2020)Modelling early events in Mycobacterium bovis infection using a co-culture model of the bovine alveolus, In: Scientific reports10(1)pp. 18495-18495 NATURE PORTFOLIO

    Bovine tuberculosis (bTB), a zoonosis mainly caused by Mycobacterium bovis has severe socio-economic consequences and impact on animal health. Host-pathogen interactions during M. bovis infection are poorly understood, especially early events which are difficult to follow in vivo. This study describes the utilisation of an in vitro co-culture model, comprising immortalised bovine alveolar type II (BATII) epithelial cells and bovine pulmonary arterial endothelial cells (BPAECs). When cultured at air-liquid interface, it was possible to follow the migration of live M. bovis Bacille Calmette-Guerin (BCG) and to observe interactions with each cell type, alongside cytokine release. Infection with BCG was shown to exert a detrimental effect primarily upon epithelial cells, with corresponding increases in IL8, TNF alpha, IL22 and IL17a cytokine release, quantified by ELISA. BCG infection increased expression of CD54, MHC Class I and II molecules in endothelial but not epithelial cells, which exhibited constitutive expression. The effect of peripheral blood mononuclear cell conditioned medium from vaccinated cattle upon apical-basolateral migration of BCG was examined by quantifying recovered BCG from the apical, membrane and basolateral fractions over time. The numbers of recovered BCG in each fraction were unaffected by the presence of PBMC conditioned medium, with no observable differences between vaccinated and naive animals.

    Marion Schuller, Rachel E Butler, Antonio Ariza, Callum Tromans-Coia, Gytis Jankevicius, Tim D W Claridge, Sharon L Kendall, Shan Goh, Graham R Stewart, Ivan Ahel (2021)Molecular basis for DarT ADP-ribosylation of a DNA base, In: Nature596pp. 597-602 Nature Research

    ADP-ribosyltransferases use NAD+ to catalyse substrate ADP-ribosylation1, and thereby regulate cellular pathways or contribute to toxin-mediated pathogenicity of bacteria2-4. Reversible ADP-ribosylation has traditionally been considered a protein-specific modification5, but recent in vitro studies have suggested nucleic acids as targets6-9. Here we present evidence that specific, reversible ADP-ribosylation ofDNA on thymidine bases occurs in cellulo through the DarT-DarG toxin-antitoxin system, which is found in a variety of bacteria (including global pathogens such as Mycobacterium tuberculosis, enteropathogenic Escherichia coli and Pseudomonas aeruginosa)10. We report the structure ofDarT, which identifies this protein as a diverged member ofthe PARP family. We provide a set of high-resolution structures of this enzyme in ligand-free and pre- and post-reaction states, which reveals a specialized mechanism of catalysis that includes a key active-site arginine that extends the canonical ADP-ribosyltransferase toolkit. Comparison with PARP-HPF1, a well-established DNA repair protein ADP-ribosylation complex, offers insights into how the DarT class ofADP-ribosyltransferases evolved into specific DNA-modifying enzymes. Together, our structural and mechanistic data provide details ofthis PARP family member and contribute to a fundamental understanding of the ADP-ribosylation of nucleic acids. We also show that thymine-linked ADP-ribose DNA adducts reversed by DarG antitoxin (functioning as a noncanonical DNA repair factor) are used not only for targeted DNA damage to induce toxicity, but also as a signalling strategy for cellular processes. Using M. tuberculosis as an exemplar, we show that DarT-DarG regulates growth by ADP-ribosylation ofDNA at the origin of chromosome replication.

    H Dawson-Hobbis, G.M Taylor, G.R Stewart (2021)A case of childhood tuberculosis from late mediaeval Somerset, England, In: Tuberculosis (Edinburgh, Scotland)128102088 Elsevier Ltd

    The remains of a 3-5 year-old child from the late mediaeval cemetery serving the Priory of St. Peter and St. Paul, Taunton, Somerset, UK was the subject of an aDNA study. The aim was to distinguish between two differential diagnoses suggested by earlier osteological examination of the remains; either tuberculosis or Langerhans cell histiocytosis. The remains tested positive for MTB complex markers, corroborating this diagnosis reached on osteological grounds. Based on positivity for the mtp40 element and a deletion in the pks15/1 locus, we conclude that infection was due to a strain of the human pathogen M.tuberculosis belonging to lineage 4. Although DNA recovered from the case was heavily fragmented, sex determination by amelogenin PCR suggested these are the remains of a young male child. The findings are discussed considering additions to the literature since the original report. Descriptions of tuberculosis in children from this period are rare and burial Sk2077 represents the first UK example of a pre-adolescent individual to have a molecular diagnosis combined with osteological pathology. This provides an important reference of childhood tuberculosis and insight into the likely presence of tuberculosis in the mediaeval adult population served by this cemetery.

    Daniel Evans, Simon Cowen, Martin Kammel, Denise M. O'Sullivan, Graham Stewart, Hans-Peter Grunert, Jacob Moran-Gilad, Jasper Verwilt, Jiwon In, Jo Vandesompele, Kathryn Harris, Ki Ho Hong, Nathaniel Storey, Suzie Hingley-Wilson, Ulf Duehring, Young-Kyung Bae, Carole A. Foy, Julian Braybrook, Heinz Zeichhardt, Jim F. Huggett (2021)The Dangers of Using Cq to Quantify Nucleic Acid in Biological Samples: A Lesson From COVID-19, In: Clinical chemistry (Baltimore, Md.)68(1)pp. 153-162 Oxford Univ Press

    Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA quantities, measured by reverse transcription quantitative PCR (RT-qPCR), have been proposed to stratify clinical risk or determine analytical performance targets. We investigated reproducibility and how setting diagnostic cutoffs altered the clinical sensitivity of coronavirus disease 2019 (COVID-19) testing. Methods Quantitative SARS-CoV-2 RNA distributions [quantification cycle (Cq) and copies/mL] from more than 6000 patients from 3 clinical laboratories in United Kingdom, Belgium, and the Republic of Korea were analyzed. Impact of Cq cutoffs on clinical sensitivity was assessed. The June/July 2020 INSTAND external quality assessment scheme SARS-CoV-2 materials were used to estimate laboratory reported copies/mL and to estimate the variation in copies/mL for a given Cq. Results When the WHO-suggested Cq cutoff of 25 was applied, the clinical sensitivity dropped to about 16%. Clinical sensitivity also dropped to about 27% when a simulated limit of detection of 10(6) copies/mL was applied. The interlaboratory variation for a given Cq value was >1000 fold in copies/mL (99% CI). Conclusion While RT-qPCR has been instrumental in the response to COVID-19, we recommend Cq (cycle threshold or crossing point) values not be used to set clinical cutoffs or diagnostic performance targets due to poor interlaboratory reproducibility; calibrated copy-based units (used elsewhere in virology) offer more reproducible alternatives. We also report a phenomenon where diagnostic performance may change relative to the effective reproduction number. Our findings indicate that the disparities between patient populations across time are an important consideration when evaluating or deploying diagnostic tests. This is especially relevant to the emergency situation of an evolving pandemic.

    Rachel E. Butler, Alex A. Smith, Tom A. Mendum, Aneesh Chandran, Huihai Wu, Louise Lefrançois, Mark Chambers, Thierry Soldati, Graham R. Stewart (2020)Mycobacterium bovis uses the ESX-1 Type VII secretion system to escape predation by the soil-dwelling amoeba Dictyostelium discoideum, In: The ISME Journal Springer Nature

    Mycobacterium bovis is the causative agent of bovine tuberculosis and the predominant cause of zoonotic tuberculosis in people. Bovine tuberculosis occurs in farmed cattle but also in a variety of wild animals, which form a reservoir of infection. Although direct transmission of tuberculosis occurs between mammals, the low frequency of contact between different host species and abundant shedding of bacilli by infected animals suggests an infectious route via environmental contamination. Other intracellular pathogens that transmit via the environment deploy strategies to survive or exploit predation by environmental amoebae. To explore if M. bovis has this capability, we investigated its interactions with the soil and dung-dwelling amoeba, Dictyostelium discoideum. We demonstrated that M. bovis evades phagocytosis and destruction by D. discoideum and actively transits through the amoeba using the ESX-1 Type VII Secretion System as part of a programme of mechanisms, many of which have been co-opted as virulence factors in the mammalian host. This capacity of M. bovis to utilise an environmental stage between mammalian hosts may enhance its transmissibility. In addition, our data provide molecular evidence to support an evolutionary role for amoebae as training grounds for the pathogenic M. tuberculosis complex.

    Alex A. Smith, Bernardo Villarreal-Ramos, Thomas A. Mendum, Kerstin J. Williams, Gareth J. Jones, Huihai Wu, Johnjoe McFadden, H. Martin Vordermeier, Graham R. Stewart (2020)Genetic screening for the protective antigenic targets of BCG vaccination, In: TUBERCULOSIS124101979 Elsevier

    Bovine tuberculosis is an important animal health problem and the predominant cause of zoonotic tuberculosis worldwide. It results in serious economic burden due to losses in productivity and the cost of control programmes. Control could be greatly improved by the introduction of an efficacious cattle vaccine but the most likely candidate, BCG, has several limitations including variable efficacy. Augmentation of BCG with a subunit vaccine booster has been shown to increase protection but the selection of antigens has hitherto been left largely to serendipity. In the present study, we take a rational approach to identify the protective antigens of BCG, selecting a BCG transposon mutant library in naïve and BCG-vaccinated cattle. Ten mutants had increased relative survival in vaccinated compared to naïve cattle, consistent with loss of protective antigen targets making the mutants less visible to the BCG immune response. The immunogenicity of three putative protective antigens, BCG_0116, BCG_0205 (YrbE1B) and BCG_1448 (PPE20) was investigated using peptide pools and PBMCs from BCG vaccinated cattle. BCG vaccination induced PBMC to release elevated levels of IP10, IL-17a and IL-10 in response to all three antigens. Taken together, the data supports the further study of these antigens for use in subunit vaccines.

    G.M Taylor, S.A Mays, G.R Stewart (2021)Analysis of a medieval strain of mycobacterium leprae from the deserted medieval village site of Wharram Percy, Yorkshire, UK, In: Journal of Archaeological Science: Reports37103015 Elsevier Ltd

    M.leprae is one of the two causative agents of human leprosy; the other being M.lepromatosis. Like M.tuberculosis complex species and other pathogens, M.leprae exhibits phylogeography, meaning that strain variation is associated with geographical regions. Strain genotyping, usually achieved by studying single nucleotide polymorphisms (SNPs), can provide information on likely origins of the disease and human migration routes in antiquity. We have previously confirmed the presence of an M.leprae SNP-type 3 strain in G708, the skeleton of a 10th-11th century individual excavated from the deserted medieval village (DMV) site of Wharram Percy, Yorkshire, UK. The present study has applied additional SNP typing methods to this case to determine the leprosy subtype. This work shows the isolate responsible for leprosy in individual G708 was of the 3I-1 subtype but with some polymorphic loci indicative of other SNP types, which could be considered as ancestral to modern exemplars of this genotype.

    Monika Dhanji-Rapkova, Mickael Teixeira Alves, Joaquin A Triñanes, Jaime Martinez-Urtaza, David Haverson, Kirsty Bradley, Craig Baker-Austin, Jim F Huggett, Graham Stewart, Jennifer M. Ritchie, Andrew D Turner (2023)Sea temperature influences accumulation of tetrodotoxin in British bivalve shellfish, In: Science of the Total Environment885163905 Elsevier

    Tetrodotoxin (TTX), a potent neurotoxin mostly associated with pufferfish poisoning, is also found in bivalve shellfish. Recent studies into this emerging food safety threat reported TTX in a few, mainly estuarine, shellfish production areas in some European countries, including the United Kingdom. A pattern in occurrences has started to emerge, however the role of temperature on TTX has not been investigated in detail. Therefore, we conducted a large systematic TTX screening study, encompassing over 3500 bivalve samples collected throughout 2016 from 155 shellfish monitoring sites along the coast of Great Britain. Overall, we found that only 1.1 % of tested samples contained TTX above the reporting limit of 2 μg/kg whole shellfish flesh and these samples all originated from ten shellfish production sites in southern England. Subsequent continuous monitoring of selected areas over a five-year period showed a potential seasonal TTX accumulation in bivalves, starting in June when water temperatures reached around 15 °C. For the first time, satellite-derived data were also applied to investigate temperature differences between sites with and without confirmed presence of TTX in 2016. Although average annual temperatures were similar in both groups, daily mean values were higher in summer and lower in winter at sites where TTX was found. Here, temperature also increased significantly faster during late spring and early summer, the critical period for TTX. Our study supports the hypothesis that temperature is one of the key triggers of events leading to TTX accumulation in European bivalves. However, other factors are also likely to play an important role, including the presence or absence of a de novo biological source, which remains elusive.

    Aneesh Chandran, Kerstin Williams, Tom Mendum, Graham Stewart, Simon Clark, Sirine Zadi, Faye Lanni, Neil McLeod, Ann Williams, Bernado Villarreal-Ramos, Martin Vordermeier, Veerasamy Maroudam, Aravind Prasad, Neeraj Bharti, Ruma Banerjee, Sunitha Manjari Kasibhatla, Johnjoe McFadden (2020)Author Correction: Development of a diagnostic compatible BCG vaccine against Bovine tuberculosis (Scientific Reports, (2019), 9, 1, (17791), 10.1038/s41598-019-54108-y), In: Scientific reports10(1)pp. 16654-16654 Nature Publishing Group UK
    Rachel Butler, Alex Smith, Tom Mendum, Aneesh Chandran, Huihai Wu, Louise Lefrancois, Thierry Soldati, Graham Stewart (2019)The great escape: dissecting the interactions between Mycobacterium bovis and the soil amoeba Dictyostelium discoideum, In: Access microbiology1(1A)
    Apoorva Bhatt, Graham R Stewart, Tobias Kieser (2002)Transposition of Tn 4560 of Streptomyces fradiae in Mycobacterium smegmatis, In: FEMS microbiology letters206(2)pp. 241-246 Elsevier B.V

    Tn 4560 (8.6 kb) was derived from Tn 4556, a Tn 3-like element from Streptomyces fradiae. It contains a viomycin resistance gene that has not been used previously for selection in mycobacteria. Tn 4560, cloned in a Streptomyces plasmid, was introduced by electroporation into Mycobacterium smegmatis mc 2155. Tn 4560 transposed into the host genome: there was no obvious target sequence preference, and insertions were in or near several conserved open reading frames. The insertions were located far apart on different AseI macrorestriction fragments. Unexpectedly, the transposon delivery plasmid, pUC1169, derived from the Streptomyces multicopy plasmid pIJ101, replicated partially in M. smegmatis, but was lost spontaneously during subculture. Replication of pUC1169 probably contributed to the relatively high efficiency of Tn 4560 delivery: up to 28% of the potential M. smegmatis transformants acquired a stable transposon insertion. The data indicated that Tn 4560 may be useful for random mutagenesis of M. smegmatis.

    GR Stewart, BD Robertson, DB Young (2003)Tuberculosis: A problem with persistence, In: NATURE REVIEWS MICROBIOLOGY1(2)pp. 97-105 NATURE PUBLISHING GROUP
    KA Wilkinson, SM Newton, GR Stewart, AR Martineau, J Patel, SM Sullivan, J-L Herrmann, O Neyrolles, DB Young, RJ Wilkinson (2009)Genetic determination of the effect of post-translational modification on the innate immune response to the 19 kDa lipoprotein of Mycobacterium tuberculosis, In: BMC MICROBIOLOGY9ARTN 9pp. ?-? BIOMED CENTRAL LTD
    GR Stewart, DB Young (2004)Heat-shock proteins and the host-pathogen interaction during bacterial infection, In: CURRENT OPINION IN IMMUNOLOGY16(4)pp. 506-510 CURRENT BIOLOGY LTD
    I Papatheodorou, M Sergot, M Randall, GR Stewart, BD Robertson (2004)Visualization of microarray results to assist interpretation, In: TUBERCULOSIS84(3-4)pp. 275-281 CHURCHILL LIVINGSTONE

    BACKGROUND: Mycobacterium tuberculosis continues to kill more people than any other bacterium. Although its archetypal host cell is the macrophage, it also enters, and survives within, dendritic cells (DCs). By modulating the behaviour of the DC, M. tuberculosis is able to manipulate the host's immune response and establish an infection. To identify the M. tuberculosis genes required for survival within DCs we infected primary human DCs with an M. tuberculosis transposon library and identified mutations with a reduced ability to survive. RESULTS: Parallel sequencing of the transposon inserts of the surviving mutants identified a large number of genes as being required for optimal intracellular fitness in DCs. Loci whose mutation attenuated intracellular survival included those involved in synthesising cell wall lipids, not only the well-established virulence factors, pDIM and cord factor, but also sulfolipids and PGL, which have not previously been identified as having a direct virulence role in cells. Other attenuated loci included the secretion systems ESX-1, ESX-2 and ESX-4, alongside many PPE genes, implicating a role for ESX-5. In contrast the canonical ESAT-6 family of ESX substrates did not have intra-DC fitness costs suggesting an alternative ESX-1 associated virulence mechanism. With the aid of a gene-nutrient interaction model, metabolic processes such as cholesterol side chain catabolism, nitrate reductase and cysteine-methionine metabolism were also identified as important for survival in DCs. CONCLUSION: We conclude that many of the virulence factors required for survival in DC are shared with macrophages, but that survival in DCs also requires several additional functions, such as cysteine-methionine metabolism, PGLs, sulfolipids, ESX systems and PPE genes.

    P Brodin, Y Poquet, F Levillain, I Peguillet, G Larrouy-Maumus, M Gilleron, F Ewann, T Christophe, D Fenistein, J Jang, M-S Jang, S-J Park, J Rauzier, J-P Carralot, R Shrimpton, A Genovesio, JA Gonzalo-Asensio, G Puzo, C Martin, R Brosch, GR Stewart, B Gicquel, O Neyrolles (2010)High Content Phenotypic Cell-Based Visual Screen Identifies Mycobacterium tuberculosis Acyltrehalose-Containing Glycolipids Involved in Phagosome Remodeling, In: PLOS PATHOGENS6(9)ARTN epp. ?-? PUBLIC LIBRARY SCIENCE
    DB Young, GR Stewart (2002)Tuberculosis vaccines, In: BRITISH MEDICAL BULLETIN62pp. 73-86 OXFORD UNIV PRESS
    HN Murphy, GR Stewart, VV Mischenko, AS Apt, R Harris, MSB McAlister, PC Driscoll, DB Young, BD Robertson (2005)The OtsAB pathway is essential for trehalose biosynthesis in Mycobacterium tuberculosis, In: JOURNAL OF BIOLOGICAL CHEMISTRY280(15)pp. 14524-14529 AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
    MCJ Blokpoel, HN Murphy, R O'Toole, S Wiles, ESC Runn, GR Stewart, DB Young, BD Robertson (2005)Tetracycline-inducible gene regulation in mycobacteria, In: NUCLEIC ACIDS RESEARCH33(2)ARTN e22 OXFORD UNIV PRESS
    GR Stewart, BD Robertson, DB Young (2004)Analysis of the function of mycobacterial DnaJ proteins by overexpression and microarray profiling, In: TUBERCULOSIS84(3-4)pp. 180-187 CHURCHILL LIVINGSTONE
    GR Stewart, KA Wilkinson, SA Newton, SA Sullivan, O Neyrolles, JR Wain, J Patel, KL Pool, DB Young, RJ Wilkinson (2005)Effect of deletion or overexpression of the 19-kilodalton lipoprotein Rv3763 on the innate response to Mycobacterium tuberculosis, In: INFECTION AND IMMUNITY73(10)pp. 6831-6837 AMER SOC MICROBIOLOGY
    H Donoghue, G Taylor, Graham Stewart, O Lee, H Wu, G Besra, D Minnikin (2017)Positive Diagnosis of Ancient Leprosy and Tuberculosis Using Ancient DNA and Lipid Biomarkers, In: Diversity9(4)46 MDPI

    Diagnosis of leprosy and tuberculosis in archaeological material is most informative when based upon entire genomes. Ancient DNA (aDNA) is often degraded but amplification of specific fragments also provides reliable diagnoses. Cell wall lipid biomarkers can distinguish ancient leprosy from tuberculosis and DNA extraction residues can be utilized. The diagnostic power of combined aDNA and lipid biomarkers is illustrated by key cases of ancient leprosy and/or tuberculosis. Human tuberculosis was demonstrated in a woman and child from Atlit-Yam (~9 ka) in the Eastern Mediterranean and in the 600 BCE Egyptian “Granville” mummy. Both aDNA and lipids confirmed Pleistocene tuberculosis in a ~17 ka bison from Natural Trap Cave, Wyoming. Leprosy is exemplified by cases from Winchester (10th–12th centuries CE) and Great Chesterford (5th–6th centuries CE). A mixed infection from Kiskundorozsma, Hungary (7th century CE) allowed lipid biomarkers to assess the relative load of leprosy and tuberculosis. Essential protocols for aDNA amplification and analysis of mycolic, mycolipenic, mycocerosic acid, and phthiocerol lipid biomarkers are summarized. Diagnoses of ancient mycobacterial disease can be extended beyond the reach of whole genomics by combinations of aDNA amplification and lipid biomarkers, with sole use of the latter having the potential to recognize even older cases.

    Tom A. Mendum, Aneesh Chandran, Kerstin Williams, H. Martin Vordermeier, Bernardo Villarreal-Ramos, H. Wu, Albel Singh, Alex A. Smith, Rachel E. Butler, Aravind Prasad, Neeraj Bharti, Ruma Banerjee, Sunitha M. Kasibhatla, Apoorva Bhatt, Graham R. Stewart, Johnjoe McFadden (2019)Transposon libraries identify novel Mycobacterium bovis BCG genes involved in the dynamic interactions required for BCG to persist during in vivo passage in cattle, In: BMC Genomics20431pp. 1-13 BMC

    Background BCG is the most widely used vaccine of all time and remains the only licensed vaccine for use against tuberculosis in humans. BCG also protects other species such as cattle against tuberculosis, but due to its incompatibility with current tuberculin testing regimens remains unlicensed. BCG’s efficacy relates to its ability to persist in the host for weeks, months or even years after vaccination. It is unclear to what degree this ability to resist the host’s immune system is maintained by a dynamic interaction between the vaccine strain and its host as is the case for pathogenic mycobacteria. Results To investigate this question, we constructed transposon mutant libraries in both BCG Pasteur and BCG Danish strains and inoculated them into bovine lymph nodes. Cattle are well suited to such an assay, as they are naturally susceptible to tuberculosis and are one of the few animal species for which a BCG vaccination program has been proposed. After three weeks, the BCG were recovered and the input and output libraries compared to identify mutants with in vivo fitness defects. Less than 10% of the mutated genes were identified as affecting in vivo fitness, they included genes encoding known mycobacterial virulence functions such as mycobactin synthesis, sugar transport, reductive sulphate assimilation, PDIM synthesis and cholesterol metabolism. Many other attenuating genes had not previously been recognised as having a virulence phenotype. To test these genes, we generated and characterised three knockout mutants that were predicted by transposon mutagenesis to be attenuating in vivo: pyruvate carboxylase, a hypothetical protein (BCG_1063), and a putative cyclopropane-fatty-acyl-phospholipid synthase. The knockout strains survived as well as wild type during in vitro culture and in bovine macrophages, yet demonstrated marked attenuation during passage in bovine lymph nodes confirming that they were indeed involved in persistence of BCG in the host. Conclusion These data show that BCG is far from passive during its interaction with the host, rather it continues to employ its remaining virulence factors, to interact with the host’s innate immune system to allow it to persist, a property that is important for its protective efficacy.

    GM Taylor, GR Stewart, M Cooke, S Chaplin, S Ladva, J Kirkup, S Palmer, DB Young (2003)Koch's Bacillus - a look at the first isolate of Mycobacterium tuberculosis from a modern perspective, In: MICROBIOLOGY-SGM149pp. 3213-3220 SOC GENERAL MICROBIOLOGY
    GR Stewart, VA Snewin, G Walzl, T Hussell, P Tormay, P O'Gaora, M Goyal, J Betts, IN Brown, DB Young (2001)Overexpression of heat-shock proteins reduces survival of Mycobacterium tuberculosis in the chronic phase of infection., In: Nat Med7(6)pp. 732-737

    Elevated expression of heat-shock proteins (HSPs) can benefit a microbial pathogen struggling to penetrate host defenses during infection, but at the same time might provide a crucial signal alerting the host immune system to its presence. To determine which of these effects predominate, we constructed a mutant strain of Mycobacterium tuberculosis that constitutively overexpresses Hsp70 proteins. Although the mutant was fully virulent in the initial stage of infection, it was significantly impaired in its ability to persist during the subsequent chronic phase. Induction of microbial genes encoding HSPs might provide a novel strategy to boost the immune response of individuals with latent tuberculosis infection.

    S Inskip, G Taylor, S Anderson, Graham Stewart (2017)Leprosy in pre-Norman Suffolk, UK: biomolecular and geochemical analysis of the woman from Hoxne, In: Journal of Medical Microbiology66pp. 1640-1649 Microbiology Society

    Purpose. A woman’s skull, exhibiting features of lepromatous leprosy (LL), was recovered from a garden in Hoxne, Suffolk. The absence of post crania and lack of formal excavation meant that diagnosis and dating was uncertain. The aim of this research was to confirm the diagnosis using biomolecular means and second, to place it in context with other British leprosy cases using SNP genotyping and radiocarbon dating. Methodology. Bone from the skull was analysed by ancient DNA (aDNA) methods and subjected to radiocarbon dating. As a result, stable carbon and nitrogen isotope values were produced, both useful for assessing aspects of the woman’s diet. Results/Key findings. aDNA confirmed the presence of mycobacterium leprae and genotyping demonstrated an ancestral variant of subtype 3I, the same lineage recently identified in living squirrels in the south of England. Radiocarbon dating revealed the woman lived approximately between 885–1015 AD, providing evidence for endurance of this subtype in East Anglia, having been previously identified as early as the fifth–sixth century (Great Chesterford) and as late as the thirteenth century (Ipswich). Conclusions. The confirmation of a new pre-Norman leprosy case in East Anglia is of interest as this is where a high proportion of cases are located. Possible factors for this may include preservation and excavation biases, population density, but also connection and trade, possibly of fur, with the continent. Future research on other British LL cases should focus on exploring these aspects to advance understanding of the disease’s history, here and on the continent.

    M Estorninho, H Smith, J Thole, J Harders-Westerveen, A Kierzek, RE Butler, O Neyrolles, GR Stewart (2010)ClgR regulation of chaperone and protease systems is essential for Mycobacterium tuberculosis parasitism of the macrophage, In: Microbiology156(11)pp. 3445-3455 Society for General Microbiology

    Chaperone and protease systems play essential roles in cellular homeostasis and have vital functions in controlling the abundance of specific cellular proteins involved in processes such as transcription, replication, metabolism and virulence. Bacteria have evolved accurate regulatory systems to control the expression and function of chaperones and potentially destructive proteases. Here, we have used a combination of transcriptomics, proteomics and targeted mutagenesis to reveal that the clp gene regulator (ClgR) of Mycobacterium tuberculosis activates the transcription of at least ten genes, including four that encode protease systems (ClpP1/C, ClpP2/C, PtrB and HtrA-like protease Rv1043c) and three that encode chaperones (Acr2, ClpB and the chaperonin Rv3269). Thus, M. tuberculosis ClgR controls a larger network of protein homeostatic and regulatory systems than ClgR in any other bacterium studied to date. We demonstrate that ClgR-regulated transcriptional activation of these systems is essential for M. tuberculosis to replicate in macrophages. Furthermore, we observe that this defect is manifest early in infection, as M. tuberculosis lacking ClgR is deficient in the ability to control phagosome pH 1 h post-phagocytosis.

    Thomas Mendum, G Michael Taylor, Helen D Donoghue, Huihai Wu, Csaba Szalontai, Antónia Marcsik, Erika Molnár, György Pálfi, Graham Stewart (2018)The Genome Sequence of a SNP Type 3K strain of Mycobacterium leprae isolated from a 7th Century Hungarian case of Lepromatous Leprosy., In: International Journal of Osteoarchaeology28(4)pp. 439-447 Wiley

    We report on a Mycobacterium leprae genome isolated from the remains of an individual with lepromatous leprosy that were excavated from a 7th century Hungarian cemetery. We determined that the genome was from a SNP type 3K0 M. leprae strain, a lineage that diverged early from other M. leprae lineages. This is one of the earliest 3K0 M. leprae genomes to be sequenced to date. A number of novel SNPs as well as SNPs characteristic of the 3K0 lineage were confirmed by conventional PCR and Sanger sequencing. Recovery of accompanying human DNA from the burial was poor, particularly when compared to that of the pathogen. Modern 3K0 M. leprae strains have only been isolated from East Asia and the Pacific and so these findings require new scenarios to describe the origins and routes of dissemination of leprosy during antiquity that have resulted in the modern phylogeographical distribution of M. leprae.

    H Mokhtar, L Biffar, S Somavarapu, J-P Frossard, Sarah Mcgowan, M Pedrera, R Strong, JC Edwards, M Garcia-Durán, MJ Rodriguez, Graham Stewart, Falko Steinbach, Simon Graham (2017)Evaluation of hydrophobic chitosan-based particulate formulations of porcine reproductive and respiratory syndrome virus vaccine candidate T cell antigens, In: Veterinary Microbiology209pp. 66-74 Elsevier

    PRRS control is hampered by the inadequacies of existing vaccines to combat the extreme diversity of circulating viruses. Since immune clearance of PRRSV infection may not be dependent on the development of neutralising antibodies and the identification of broadly- neutralising antibody epitopes have proven elusive we hypothesised that conserved T cell antigens represent potential candidates for development of a novel PRRS vaccine. Previously we had identified the M and NSP5 proteins as well-conserved targets of polyfunctional CD8 and CD4 T cells. To assess their vaccine potential, peptides representing M and NSP5 were encapsulated in hydrophobically-modified chitosan particles adjuvanted by incorporation of a synthetic multi-TLR2/TLR7 agonist and coated with a model B cell PRRSV antigen. For comparison, empty particles and adjuvanted particles encapsulating inactivated PRRSV-1

    Giselda Bucca, Radhika Pothi, Andrew Hesketh, Carla Moller-Levet, David A Hodgson, Emma Laing, Graham Stewart, Colin Smith (2018)Translational control plays an important role in the adaptive heat-shock response of Streptomyces coelicolor., In: Nucleic Acids Research46(11)pp. 5692-5703 Oxford University Press

    Stress-induced adaptations requiremultiple levels of regulation in all organisms to repair cellular damage. In the present study we evaluated the genome-wide transcriptional and translational changes following heat stress exposure in the soil-dwelling model actinomycete bacterium, Streptomyces coelicolor. The combined analysis revealed an unprecedented level of translational control of gene expression, deduced through polysome profiling, in addition to transcriptional changes. Our data show little correlation between the transcriptome and ‘translatome’; while an obvious downward trend in genome wide transcription was observed, polysome associated transcripts following heat-shock showed an opposite upward trend. A handful of key protein players, including the major molecular chaperones and proteases were highly induced at both the transcriptional and translational level following heat-shock, a phenomenon known as ‘potentiation’. Many other transcripts encoding cold-shock proteins, ABC-transporter systems, multiple transcription factors weremore highly polysome-associated following heat stress; interestingly, these protein families were not induced at the transcriptional level and therefore were not previously identified as part of the stress response. Thus, stress coping mechanisms at the level of gene expression in this bacterium go well beyond the induction of a relatively small number of molecular chaperones and proteases in order to ensure cellular survival at non-physiological temperatures.

    DJ Beste, M Espasa, B Bonde, AM Kierzek, GR Stewart, J McFadden (2009)The genetic requirements for fast and slow growth in mycobacteria., In: PLoS One4(4)e5349 PLoS

    Mycobacterium tuberculosis infects a third of the world's population. Primary tuberculosis involving active fast bacterial replication is often followed by asymptomatic latent tuberculosis, which is characterised by slow or non-replicating bacteria. Reactivation of the latent infection involving a switch back to active bacterial replication can lead to post-primary transmissible tuberculosis. Mycobacterial mechanisms involved in slow growth or switching growth rate provide rational targets for the development of new drugs against persistent mycobacterial infection. Using chemostat culture to control growth rate, we screened a transposon mutant library by Transposon site hybridization (TraSH) selection to define the genetic requirements for slow and fast growth of Mycobacterium bovis (BCG) and for the requirements of switching growth rate. We identified 84 genes that are exclusively required for slow growth (69 hours doubling time) and 256 genes required for switching from slow to fast growth. To validate these findings we performed experiments using individual M. tuberculosis and M. bovis BCG knock out mutants. We have demonstrated that growth rate control is a carefully orchestrated process which requires a distinct set of genes encoding several virulence determinants, gene regulators, and metabolic enzymes. The mce1 locus appears to be a component of the switch to slow growth rate, which is consistent with the proposed role in virulence of M. tuberculosis. These results suggest novel perspectives for unravelling the mechanisms involved in the switch between acute and persistent TB infections and provide a means to study aspects of this important phenomenon in vitro.

    Verena J Schuenemann, Charlotte Avanzi, Ben Krause-Kyora, Alexander Seitz, Alexander Herbig, Sarah Inskip, Marion Bonazzi, Ella Reiter, Christian Urban, Dorthe Dangvard Pedersen, G Michael Taylor, Pushpendra Singh, Graham Stewart, Petr Veleminsky, Jakub Likovsky, Antonia Marcsik, Erika Molnar, Gyorgy Palfi, Valentina Mariotti, Alessandro Riga, M Giovanna Belcastro, Jesper L Boldsen, Almut Nebel, Simon Mays, Helen D Donoghue, Sonia Zakrzewski, Andrej Benjak, Kay Nieselt, Stewart T Cole, Johannes Krause (2018)Ancient Mycobacterium leprae genomes reveal a high diversity of Mycobacterium leprae in medieval Europe, In: PLOS Pathogens14(5)e1006997 Public Library of Science

    Studying ancient DNA allows us to retrace the evolutionary history of human pathogens, such as Mycobacterium leprae, the main causative agent of leprosy. Leprosy is one of the oldest recorded and most stigmatizing diseases in human history. The disease was prevalent in Europe until the 16th century and is still endemic in many countries with over 200,000 new cases reported annually. Previous worldwide studies on modern and European medieval M. leprae genomes revealed that they cluster into several distinct branches of which two were present in medieval Northwestern Europe. In this study, we analyzed 10 new medieval M. leprae genomes including the so far oldest M. leprae genome from one of the earliest known cases of leprosy in the United KingdomÐa skeleton from the Great Chesterford cemetery with a calibrated age of 415±545 C.E. This dataset provides a genetic time transect of M. leprae diversity in Europe over the past 1500 years. We find M. leprae strains from four distinct branches to be present in the Early Medieval Period, and strains from three different branches were detected within a single cemetery from the High Medieval Period. Altogether these findings suggest a higher genetic diversity of M. leprae strains in medieval Europe at various time points than previously assumed. The resulting more complex picture of the past phylogeography of leprosy in Europe impacts current phylogeographical models of M. leprae dissemination. It suggests alternative models for the past spread of leprosy such as a wide spread prevalence of strains from different branches in Eurasia already in Antiquity or maybe even an origin in Western Eurasia. Furthermore, these results highlight how studying ancient M. leprae strains improves understanding the history of leprosy worldwide.

    GR Stewart, J Patel, BD Robertson, A Rae, DB Young (2005)Mycobacterial mutants with defective control of phagosomal acidification, In: PLOS PATHOGENS1(3)ARTN epp. 269-278 PUBLIC LIBRARY SCIENCE
    GR Stewart, RN Perry, DJ Wright (2001)Occurrence of dopamine in Panagrellus redivivus and Meloidogyne incognita, In: NEMATOLOGY3pp. 843-848 BRILL ACADEMIC PUBLISHERS
    A Bhatt, GR Stewart, T Kieser (2002)Transposition of Tn4560 of Streptomyces fradiae in Mycobacterium smegmatis, In: FEMS MICROBIOLOGY LETTERS206(2)pp. 241-246 ELSEVIER SCIENCE BV
    DJV Beste, T Hooper, G Stewart, B Bonde, C Avignone-Rossa, M Bushell, P Wheeler, S Klamt, AM Kierzek, J McFadden (2007)GSMN-TB: a web-based genome scale network model of Mycobacterium tuberculosis metabolism, In: GENOME BIOLOGY8(5)ARTN rpp. ?-? BIOMED CENTRAL LTD
    Rachel Butler, N Krishnan, W Garcia-Jimenez, R Francis, A Martyn, T Mendum, Shaza Felemban, Nicolas Locker, J Salguero Bodes, B Robertson, Graham Stewart (2017)Susceptibility of M. tuberculosis-infected host cells to phospho-MLKL driven necroptosis is dependent on cell type and presence of TNFα, In: Virulence8(8)pp. 1820-1832 Taylor & Francis

    An important feature of Mycobacterium tuberculosis pathogenesis is the ability to control cell death in infected host cells, including inhibition of apoptosis and stimulation of necrosis. Recently an alternative form of programmed cell death, necroptosis, has been described where necrotic cell death is induced by apoptotic stimuli under conditions where apoptotic execution is inhibited. We show for the first time that M. tuberculosis and TNFα synergise to induce necroptosis in murine fibroblasts via RIPK1-dependent mechanisms and characterized by phosphorylation of Ser345 of the MLKL necroptosis death effector. However, in murine macrophages M. tuberculosis and TNFα induce non-necroptotic cell death that is RIPK1-dependent but independent of MLKL phosphorylation. Instead, M. tuberculosis-infected macrophages undergo RIPK3-dependent cell death which occurs both in the presence and absence of TNFα and involves the production of mitochondrial ROS. Immunocytochemical staining for MLKL phosphorylation further demonstrated the occurrence of necroptosis in vivo in murine M. tuberculosis granulomas. Phosphorylated- MLKL immunoreactivity was observed associated with the cytoplasm and nucleus of fusiform cells in M. tuberculosis lesions but not in proximal macrophages. Thus whereas pMLKL-driven necroptosis does not appear to be a feature of M. tuberculosis-infected macrophage cell death, it may contribute to TNFα-induced cytotoxicity of the lung stroma and therefore contribute to necrotic cavitation and bacterial dissemination.

    TA Mendum, VJ Schuenemann, S Roffey, GM Taylor, H Wu, P Singh, K Tucker, J Hinds, ST Cole, AM Kierzek, K Nieselt, J Krause, GR Stewart (2014)Mycobacterium leprae genomes from a British medieval leprosy hospital: towards understanding an ancient epidemic, In: BMC GENOMICS15ARTN 2pp. ?-? BIOMED CENTRAL LTD
    VV Yeremeev, GR Stewart, O Neyrolles, K Skrabal, VG Avdienko, AS Apt, DB Young (2000)Deletion of the 19kDa antigen does not alter the protective efficacy of BCG, In: TUBERCLE AND LUNG DISEASE80(6)pp. 243-247 CHURCHILL LIVINGSTONE
    O Dussurget, G Stewart, O Neyrolles, P Pescher, D Young, G Marchal (2001)Role of Mycobacterium tuberculosis copper-zinc superoxide dismutase, In: INFECTION AND IMMUNITY69(1)pp. 529-533 AMER SOC MICROBIOLOGY
    GR Stewart, S Ehrt, LW Riley, JW Dale, J McFadden (2000)Deletion of the putative antioxidant noxR1 does not alter the virulence of Mycobacterium tuberculosis H37Rv, In: TUBERCLE AND LUNG DISEASE80(4-5)pp. 237-242 CHURCHILL LIVINGSTONE
    IR Humphreys, GR Stewart, DJ Turner, J Patel, D Karamanou, RJ Snelgrove, DB Young (2006)A role for dendritic cells in the dissemination of mycobacterial infection, In: MICROBES AND INFECTION8(5)pp. 1339-1346 ELSEVIER SCIENCE BV
    M Henao-Tamayo, AP Junqueira-Kipnis, D Ordway, M Gonzales-Juaffero, GR Stewart, DB Young, RJ Wilkinson, RJ Basaraba, IM Orme (2007)A mutant of Mycobacterium tuberculosis lacking the 19-kDa lipoprotein Rv3763 is highly attenuated in vivo but retains potent vaccinogenic properties, In: VACCINE25(41)pp. 7153-7159 ELSEVIER SCI LTD
    GR Stewart, L Wermisch, R Stabler, JA Mangan, J Hinds, KG Laing, PD Butcher, DB Young (2002)The heat shock response of Mycobacterium tuberculosis: linking gene expression, immunology and pathogenesis, In: COMPARATIVE AND FUNCTIONAL GENOMICS3(4)pp. 348-351 JOHN WILEY & SONS LTD
    S Pitarque, JL Herrmann, JL Duteyrat, M Jackson, GR Stewart, F Lecointe, B Payre, O Schwartz, DB Young, G Marchal, PH Lagrange, G Puzo, B Gicquel, J Nigou, O Neyrolles (2005)Deciphering the molecular bases of Mycobacterium tuberculosis binding to the lectin DC-SIGN reveals an underestimated complexity, In: BIOCHEMICAL JOURNAL392pp. 615-624 PORTLAND PRESS LTD
    GR Stewart, SM Newton, KA Wilkinson, IR Humphreys, HN Murphy, BD Robertson, RJ Wilkinson, DB Young (2005)The stress-responsive chaperone alpha-crystallin 2 is required for pathogenesis of Mycobacterium tuberculosis, In: MOLECULAR MICROBIOLOGY55(4)pp. 1127-1137 BLACKWELL PUBLISHING LTD
    SM Newton, RJ Smith, KA Wilkinson, MP Nicol, NJ Garton, KJ Staples, GR Stewart, JR Wain, AR Martineau, S Fandrich, T Smallie, B Foxwell, A Al-Obaidi, J Shafi, K Rajakumar, B Kampmann, PW Andrew, L Ziegler-Heitbrock, MR Barer, RJ Wilkinson (2006)A deletion defining a common Asian lineage of Mycobacterium tuberculosis associates with immune subversion, In: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA103(42)pp. 15594-15598 NATL ACAD SCIENCES
    Huihai Wu, A von Kamp, Vytautas Leoncikas, W Mori, N Sahin, A Gevorgyan, C Linley, M Grabowski, AA Mannan, Nicholas Stoy, Graham Stewart, LT Ward, David Lewis, J Sroka, H Matsuno, S Klamt, HV Westerhoff, Johnjoe McFadden, NJ Plant, Andrzej Kierzek (2016)MUFINS: Multi-Formalism Interaction Network Simulator, In: NPJ Systems Biology and Applications216032 Nature Publishing Group

    Systems Biology has established numerous approaches for mechanistic modelling of molecular networks in the cell and a legacy of models. The current frontier is the integration of models expressed in different formalisms to address the multi-scale biological system organisation challenge. We present MUFINS software, implementing a unique set of approaches for multiformalism simulation of interaction networks. We extend the constraint-based modelling (CBM) framework by incorporation of linear inhibition constraints, enabling for the first time linear modelling of networks simultaneously describing gene regulation, signalling and whole-cell metabolism at steady state. We present a use case where a logical hypergraph model of a regulatory network is expressed by linear constraints and integrated with a Genome Scale Metabolic Network (GSMN) of mouse macrophage. We experimentally validate predictions, demonstrating application of our software in an iterative cycle of hypothesis generation, validation and model refinement. MUFINS incorporates an extended version of our Quasi Steady State Petri Net approach to integrate dynamic models with CBM, which we demonstrate through a dynamic model of cortisol signalling integrated with the human Recon2 GSMN and a model of nutrient dynamics in physiological compartments. Finally, we implement a number of methods for deriving metabolic states from ~omics data, including our new variant of the iMAT congruency approach. We compare our approach with iMAT through analysis of 262 individual tumour transcriptomes, recovering features of metabolic reprogramming in cancer. The software provides graphics user interface with network visualisation, which facilitates use by researchers who are not experienced in coding and mathematical modelling environments.

    RE Butler, P Brodin, J Jang, MS Jang, BD Robertson, B Gicquel, GR Stewart (2012)The balance of apoptotic and necrotic cell death in Mycobacterium tuberculosis infected macrophages is not dependent on bacterial virulence., In: PLoS One7(10)pp. e47573-? Public Library of Science

    An important mechanism of Mycobacterium tuberculosis pathogenesis is the ability to control cell death pathways in infected macrophages: apoptotic cell death is bactericidal, whereas necrotic cell death may facilitate bacterial dissemination and transmission.

    G. R. Stewart, R. N. Perry, D. J. Wright (1993)Studies on the amphid specific glycoprotein gp32 in different life-cycle stages of Meloidogyne species, In: Parasitology107(5)pp. 573-578 Cambridge University Press

    Indirect immunofluorescent studies have been used to localize a glycoprotein (gp32) in the amphids of 2nd-stage juveniles (J2) of Meloidogyne incognita parasitic in the roots of tomato plants, male Meloidogyne javanica and some young adult female M. incognita. Immuno-electron microscopic studies showed an apparent absence of gp32 in the amphids of mature adult female M. incognita. Chemoattraction experiments demonstrated that the binding of gp32 antibodies to the amphidial secretions of infective J2 M. incognita partly impaired the ability of the nematodes to locate tomato roots.

    G. R. Stewart, R. N. Perry, J. Alexander, D. J. Wright (1993)A glycoprotein specific to the amphids of Meloidogyne species, In: Parasitology106(4)pp. 405-412 Cambridge University Press

    Indirect immunofluorescence studies using a rabbit polyclonal antiserum have been used to localize the presence of a 32 kDa glycoprotein in the region of the amphids of 2nd-stage juveniles of the root-knot nematode, Meloidogyne incognita. Similar immunoreactivity was also demonstrated in 5 other Meloidogyne species but was not found in representatives of 8 other nematode genera including the closely related cyst nematodes (Globodera and Heterodera). Immunoelectron microscopical studies have shown that the immunoreactivity in M. incognita is associated with the secretory material filling the amphidial channel and probably with the sheath cell.

    Sandra M. Newton, Rebecca J. Smith, Katalin A. Wilkinson, Mark P. Nicol, Natalie J. Garton, Karl J. Staples, Graham R. Stewart, John R. Wain, Adrian R. Martineau, Sarah Fandrich, Timothy Smallie, Brian Foxwell, Ahmed Al-Obaidi, Jamila Shafi, Kumar Rajakumar, Beate Kampmann, Peter W. Andrew, Loems Ziegler-Heitbrock, Michael R. Barer, Robert J. Wilkinson (2007)A deletion defining a common Asian lineage of Mycobacterium tuberculosis associates with immune subversion (vol 103, pg 15594, 2006), In: Proceedings of the National Academy of Sciences - PNAS104(2)pp. 685-685 Natl Acad Sciences
    KA Wilkinson, GR Stewart, SM Newton, HM Vordermeier, JR Wain, HN Murphy, K Horner, DB Young, RJ Wilkinson (2005)Infection biology of a novel alpha-crystallin of Mycobacterium tuberculosis: Acr2, In: JOURNAL OF IMMUNOLOGY174(7)pp. 4237-4243 AMER ASSOC IMMUNOLOGISTS
    R El Kadri, A Bermudez-Fajardo, M Puolakkainen, G Stewart, E Oviedo-Orta (2010)Anti-inflammatory and atheroprotective effects of Chlamydia pneumoniae recombinant MOMP, In: ATHEROSCLEROSIS213(1)pp. E6-E6
    RAS Elkadri, A-K Grobler, A Bermudez-Fajardo, M Puolakkainen, G Stewart, E Oviedo-Orta (2009)Effects of recombinant vectors expressing Chlamydia pneumoniae's major outer membrane protein (MOMP) on humoral and T cell-mediated immunity., In: JOURNAL OF IMMUNOLOGY182 AMER ASSOC IMMUNOLOGISTS
    DE Minnikin, GM Taylor, GR Stewart, TA Mendum, S Roffey, K Tucker, OY-C Lee, HHT Wu, GS Besra, ST Cole (2014)Defining the origins and spread of leprosy using molecular biomarkers, In: AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY153pp. 186-187
    R El-Kadri, A Bermudez-Fajardo, G Stewart, M Puolakkainen, E Oviedo-Orta (2010)Anti-inflammatory and atheroprotectiveeffects of Chlamyiphia pneumoniaerecombinant MOMP, In: IMMUNOLOGY131pp. 131-131
    JE Bradley, BM Atogho, L Elson, GR Stewart, M Boussinesq (1998)A cocktail of recombinant Onchocerca volvulus antigens for serologic diagnosis with the potential to predict the endemicity of onchocerciasis infection, In: AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE59(6)pp. 877-882 AMER SOC TROP MED & HYGIENE
    R El Kadri, A Bermudez-Fajardo, M Puolakkainen, G Stewart, E Oviedo-Orta (2010)Effect of immunisation with C. pneumoniae rMOMP on atherosclerosis development, In: ATHEROSCLEROSIS213(1)pp. E13-E13
    GR Stewart, M Boussinesq, T Coulson, L Elson, T Nutman, JE Bradley (1999)Onchocerciasis modulates the immune response to mycobacterial antigens, In: CLINICAL AND EXPERIMENTAL IMMUNOLOGY117(3)pp. 517-523 BLACKWELL SCIENCE LTD
    A Ciaramella, A Cavone, MB Santucci, SK Garg, N Sanarico, M Bocchino, D Galati, A Martino, G Auricchio, M D'Orazio, GR Stewart, O Neyrolles, DB Young, V Colizzi, M Fraziano (2004)Induction of apoptosis and release of interleukin-1 beta by cell wall-associated 19-kDa lipoprotein during the course of mycobacterial infection, In: JOURNAL OF INFECTIOUS DISEASES190(6)pp. 1167-1176
    GR Stewart, L Wernisch, R Stabler, JA Mangan, J Hinds, KG Laing, DB Young, PD Butcher (2002)Dissection of the heat-shock response in Myobacterium tuberculosis using mutants and microarrays, In: MICROBIOLOGY-SGM148pp. 3129-3138 SOC GENERAL MICROBIOLOGY
    GR Stewart, YH Zhu, W Parredes, TIM Tree, R Guderian, JE Bradley (1997)Novel cuticular collagen Ovcol-1 of Onchocerca volvulus is preferentially recognized by immunoglobulin G3 from putatively immune individuals, In: INFECTION AND IMMUNITY65(1)pp. 164-170 AMER SOC MICROBIOLOGY