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Derqui N, Koycheva A, Zhou J, Pillay TD, Crone MA, Hakki S, Fenn J, Kundu R, Varro R, Conibear E, Madon KJ, Barnett JL, Houston H, Singanayagam A, Narean JS, Tolosa-Wright MR, Mosscrop L, Rosadas C, Watber P, Anderson C, Parker E, Freemont PS, Ferguson NM, Zambon M, McClure MO, Tedder R, Barclay WS, Dunning J, Taylor GP, Lalvani A, Cutajar J, Quinn V, Hammett S, McDermott E, Luca C, Timcang K, Samuel J, Bremang S, Evetts S, Wang L, Nevin S, Davies M, Tejpal C, Essoussi M, Ketkar AV, Miserocchi G, Catchpole H, Badhan A, Dustan S, Day Weber IJ, Marchesin F, Whitfield MG, Poh J, Kondratiuk A. Risk factors and vectors for SARS-CoV-2 household transmission: a prospective, longitudinal cohort study. The Lancet Microbe 2023:S2666-5247(23)00069-1. [PMID: 37031689 PMCID: PMC10132910 DOI: 10.1016/s2666-5247(23)00069-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 02/15/2023] [Accepted: 02/15/2023] [Indexed: 04/09/2023] Open
Abstract
BACKGROUND Despite circumstantial evidence for aerosol and fomite spread of SARS-CoV-2, empirical data linking either pathway with transmission are scarce. Here we aimed to assess whether the presence of SARS-CoV-2 on frequently-touched surfaces and residents' hands was a predictor of SARS-CoV-2 household transmission. METHODS In this longitudinal cohort study, during the pre-alpha (September to December, 2020) and alpha (B.1.1.7; December, 2020, to April, 2021) SARS-CoV-2 variant waves, we prospectively recruited contacts from households exposed to newly diagnosed COVID-19 primary cases, in London, UK. To maximally capture transmission events, contacts were recruited regardless of symptom status and serially tested for SARS-CoV-2 infection by RT-PCR on upper respiratory tract (URT) samples and, in a subcohort, by serial serology. Contacts' hands, primary cases' hands, and frequently-touched surface-samples from communal areas were tested for SARS-CoV-2 RNA. SARS-CoV-2 URT isolates from 25 primary case-contact pairs underwent whole-genome sequencing (WGS). FINDINGS From Aug 1, 2020, until March 31, 2021, 620 contacts of PCR-confirmed SARS-CoV-2-infected primary cases were recruited. 414 household contacts (from 279 households) with available serial URT PCR results were analysed in the full household contacts' cohort, and of those, 134 contacts with available longitudinal serology data and not vaccinated pre-enrolment were analysed in the serology subcohort. Household infection rate was 28·4% (95% CI 20·8-37·5) for pre-alpha-exposed contacts and 51·8% (42·5-61·0) for alpha-exposed contacts (p=0·0047). Primary cases' URT RNA viral load did not correlate with transmission, but was associated with detection of SARS-CoV-2 RNA on their hands (p=0·031). SARS-CoV-2 detected on primary cases' hands, in turn, predicted contacts' risk of infection (adjusted relative risk [aRR]=1·70 [95% CI 1·24-2·31]), as did SARS-CoV-2 RNA presence on household surfaces (aRR=1·66 [1·09-2·55]) and contacts' hands (aRR=2·06 [1·57-2·69]). In six contacts with an initial negative URT PCR result, hand-swab (n=3) and household surface-swab (n=3) PCR positivity preceded URT PCR positivity. WGS corroborated household transmission. INTERPRETATION Presence of SARS-CoV-2 RNA on primary cases' and contacts' hands and on frequently-touched household surfaces associates with transmission, identifying these as potential vectors for spread in households. FUNDING National Institute for Health Research Health Protection Research Unit in Respiratory Infections, Medical Research Council.
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Hakki S, Zhou J, Jonnerby J, Singanayagam A, Barnett JL, Madon KJ, Koycheva A, Kelly C, Houston H, Nevin S, Fenn J, Kundu R, Crone MA, Pillay TD, Ahmad S, Derqui-Fernandez N, Conibear E, Freemont PS, Taylor GP, Ferguson N, Zambon M, Barclay WS, Dunning J, Lalvani A, Badhan A, Varro R, Luca C, Quinn V, Cutajar J, Nichols N, Russell J, Grey H, Ketkar A, Miserocchi G, Tejpal C, Catchpole H, Nixon K, Di Biase B, Hopewell T, Narean JS, Samuel J, Timcang K, McDermott E, Bremang S, Hammett S, Evetts S, Kondratiuk A. Onset and window of SARS-CoV-2 infectiousness and temporal correlation with symptom onset: a prospective, longitudinal, community cohort study. The Lancet Respiratory Medicine 2022; 10:1061-1073. [PMID: 35988572 PMCID: PMC9388060 DOI: 10.1016/s2213-2600(22)00226-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 05/24/2022] [Accepted: 06/08/2022] [Indexed: 12/05/2022]
Abstract
Background Knowledge of the window of SARS-CoV-2 infectiousness is crucial in developing policies to curb transmission. Mathematical modelling based on scarce empirical evidence and key assumptions has driven isolation and testing policy, but real-world data are needed. We aimed to characterise infectiousness across the full course of infection in a real-world community setting. Methods The Assessment of Transmission and Contagiousness of COVID-19 in Contacts (ATACCC) study was a UK prospective, longitudinal, community cohort of contacts of newly diagnosed, PCR-confirmed SARS-CoV-2 index cases. Household and non-household exposed contacts aged 5 years or older were eligible for recruitment if they could provide informed consent and agree to self-swabbing of the upper respiratory tract. The primary objective was to define the window of SARS-CoV-2 infectiousness and its temporal correlation with symptom onset. We quantified viral RNA load by RT-PCR and infectious viral shedding by enumerating cultivable virus daily across the course of infection. Participants completed a daily diary to track the emergence of symptoms. Outcomes were assessed with empirical data and a phenomenological Bayesian hierarchical model. Findings Between Sept 13, 2020, and March 31, 2021, we enrolled 393 contacts from 327 households (the SARS-CoV-2 pre-alpha and alpha variant waves); and between May 24, 2021, and Oct 28, 2021, we enrolled 345 contacts from 215 households (the delta variant wave). 173 of these 738 contacts were PCR positive for more than one timepoint, 57 of which were at the start of infection and comprised the final study population. The onset and end of infectious viral shedding were captured in 42 cases and the median duration of infectiousness was 5 (IQR 3–7) days. Although 24 (63%) of 38 cases had PCR-detectable virus before symptom onset, only seven (20%) of 35 shed infectious virus presymptomatically. Symptom onset was a median of 3 days before both peak viral RNA and peak infectious viral load (viral RNA IQR 3–5 days, n=38; plaque-forming units IQR 3–6 days, n=35). Notably, 22 (65%) of 34 cases and eight (24%) of 34 cases continued to shed infectious virus 5 days and 7 days post-symptom onset, respectively (survival probabilities 67% and 35%). Correlation of lateral flow device (LFD) results with infectious viral shedding was poor during the viral growth phase (sensitivity 67% [95% CI 59–75]), but high during the decline phase (92% [86–96]). Infectious virus kinetic modelling suggested that the initial rate of viral replication determines the course of infection and infectiousness. Interpretation Less than a quarter of COVID-19 cases shed infectious virus before symptom onset; under a crude 5-day self-isolation period from symptom onset, two-thirds of cases released into the community would still be infectious, but with reduced infectious viral shedding. Our findings support a role for LFDs to safely accelerate deisolation but not for early diagnosis, unless used daily. These high-resolution, community-based data provide evidence to inform infection control guidance. Funding National Institute for Health and Care Research.
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Reuschl AK, Edwards MR, Parker R, Connell DW, Hoang L, Halliday A, Jarvis H, Siddiqui N, Wright C, Bremang S, Newton SM, Beverley P, Shattock RJ, Kon OM, Lalvani A. Innate activation of human primary epithelial cells broadens the host response to Mycobacterium tuberculosis in the airways. PLoS Pathog 2017; 13:e1006577. [PMID: 28863187 PMCID: PMC5605092 DOI: 10.1371/journal.ppat.1006577] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Revised: 09/19/2017] [Accepted: 08/11/2017] [Indexed: 01/17/2023] Open
Abstract
Early events in the human airways determining whether exposure to Mycobacterium tuberculosis (Mtb) results in acquisition of infection are poorly understood. Epithelial cells are the dominant cell type in the lungs, but little is known about their role in tuberculosis. We hypothesised that human primary airway epithelial cells are part of the first line of defense against Mtb-infection and contribute to the protective host response in the human respiratory tract. We modelled these early airway-interactions with human primary bronchial epithelial cells (PBECs) and alveolar macrophages. By combining in vitro infection and transwell co-culture models with a global transcriptomic approach, we identified PBECs to be inert to direct Mtb-infection, yet to be potent responders within an Mtb-activated immune network, mediated by IL1β and type I interferon (IFN). Activation of PBECs by Mtb-infected alveolar macrophages and monocytes increased expression of known and novel antimycobacterial peptides, defensins and S100-family members and epithelial-myeloid interactions further shaped the immunological environment during Mtb-infection by promoting neutrophil influx. This is the first in depth analysis of the primary epithelial response to infection and offers new insights into their emerging role in tuberculosis through complementing and amplifying responses to Mtb. Mycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis, which remains a major public health burden today. In the majority of cases, infection is acquired by inhalation of aerosolised bacteria. Mtb is thought to target alveolar macrophages in the lower airways to establish infection. However, the cells predominantly lining the respiratory tract are epithelial cells and thus are likely crucial during the early host-pathogen interactions. We recovered primary human bronchial epithelial cells from healthy volunteers to assess their global transcriptomic response to direct Mtb-exposure and exposure to Mtb-infected myeloid cells. Our analysis revealed that, while being inert to direct Mtb-infection, epithelial cells were highly responsive to soluble mediators released by infected macrophages. The epithelial response induced by this cellular cross-talk, promoted neutrophil influx in vitro as well as the increase of antimycobaterial host responses. Our data provide novel and unexpected insights into the role of the primary human airway epithelium and define a non-redundant role for epithelial cells in shaping the local immunological environment at the site of initial Mtb infection.
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Affiliation(s)
- Ann-Kathrin Reuschl
- Tuberculosis Research Centre, National Heart and Lung Institute, Imperial College London, St Mary’s Campus, London, United Kingdom
| | - Michael R. Edwards
- Department of Cytopathology, Imperial College London, St Mary’s Hospital, Imperial College NHS Trust, London, United Kingdom
| | - Robert Parker
- Tuberculosis Research Centre, National Heart and Lung Institute, Imperial College London, St Mary’s Campus, London, United Kingdom
| | - David W. Connell
- Tuberculosis Research Centre, National Heart and Lung Institute, Imperial College London, St Mary’s Campus, London, United Kingdom
| | - Long Hoang
- Tuberculosis Research Centre, National Heart and Lung Institute, Imperial College London, St Mary’s Campus, London, United Kingdom
| | - Alice Halliday
- Tuberculosis Research Centre, National Heart and Lung Institute, Imperial College London, St Mary’s Campus, London, United Kingdom
| | - Hannah Jarvis
- Tuberculosis Research Centre, National Heart and Lung Institute, Imperial College London, St Mary’s Campus, London, United Kingdom
| | - Nazneen Siddiqui
- Tuberculosis Research Centre, National Heart and Lung Institute, Imperial College London, St Mary’s Campus, London, United Kingdom
| | - Corrina Wright
- Respiratory Medicine, National Heart and Lung Institute, Imperial College London, St Mary’s Campus, Norfolk Place, London, United Kingdom
| | - Samuel Bremang
- Tuberculosis Research Centre, National Heart and Lung Institute, Imperial College London, St Mary’s Campus, London, United Kingdom
| | - Sandra M. Newton
- Section of Paediatrics, Department of Medicine, St Mary’s Campus, Imperial College, London, United Kingdom
| | - Peter Beverley
- Tuberculosis Research Centre, National Heart and Lung Institute, Imperial College London, St Mary’s Campus, London, United Kingdom
| | - Robin J. Shattock
- Department of Medicine, Imperial College London, St Mary’s Campus, London, United Kingdom
| | - Onn Min Kon
- Tuberculosis Research Centre, National Heart and Lung Institute, Imperial College London, St Mary’s Campus, London, United Kingdom
| | - Ajit Lalvani
- Tuberculosis Research Centre, National Heart and Lung Institute, Imperial College London, St Mary’s Campus, London, United Kingdom
- * E-mail:
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Halliday A, Whitworth H, Kottoor SH, Niazi U, Menzies S, Kunst H, Bremang S, Badhan A, Beverley P, Kon OM, Lalvani A. Stratification of Latent Mycobacterium tuberculosis Infection by Cellular Immune Profiling. J Infect Dis 2017; 215:1480-1487. [PMID: 28329119 PMCID: PMC5451604 DOI: 10.1093/infdis/jix107] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 02/23/2017] [Indexed: 12/21/2022] Open
Abstract
Background. Recently acquired and remotely acquired latent Mycobacterium tuberculosis infection (LTBI) are clinically indistinguishable, yet recent acquisition of infection is the greatest risk factor for progression to tuberculosis in immunocompetent individuals. We aimed to evaluate the ability of cellular immune signatures that differ between active tuberculosis and LTBI to distinguish recently from remotely acquired LTBI. Methods. Fifty-nine individuals were recruited: 20 had active tuberculosis, 19 had recently acquired LTBI, and 20 had remotely acquired LTBI. The proportion of mycobacteria-specific CD4+ T cells secreting tumor necrosis factor α (TNF-α) but not interferon γ or interleukin 2 which had a differentiated effector phenotype (TNF-α–only TEFF), and the level of CD27 expression on IFN-γ–producing CD4+ T cells, were detected by flow cytometry. Results. The TNF-α–only TEFF signature was significantly higher in the group with recently acquired LTBI, compared with the group with remotely acquired LTBI (P < .0001), and it discriminated between these groups with high sensitivity and specificity, with an area under the curve of 0.87. Two signatures incorporating CD27 expression did not distinguish between recently and remotely acquired LTBI. Interestingly, the TNF-α–only TEFF signature in participants with recently acquired LTBI was more similar to that in participants with tuberculosis than that in participants with remotely acquired LTBI, suggesting that recently acquired LTBI is immunologically more similar to tuberculosis than remotely acquired LTBI. Conclusions. These findings reveal marked biological heterogeneity underlying the clinically homogeneous phenotype of LTBI, providing a rationale for immunological risk stratification to improve targeting of LTBI treatment.
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Affiliation(s)
- Alice Halliday
- Tuberculosis Research Centre, Respiratory Medicine, National Heart and Lung Institute, Imperial College London, St Mary's Campus
| | - Hilary Whitworth
- Tuberculosis Research Centre, Respiratory Medicine, National Heart and Lung Institute, Imperial College London, St Mary's Campus
| | - Sherine Hermagild Kottoor
- Tuberculosis Research Centre, Respiratory Medicine, National Heart and Lung Institute, Imperial College London, St Mary's Campus
| | - Umar Niazi
- Tuberculosis Research Centre, Respiratory Medicine, National Heart and Lung Institute, Imperial College London, St Mary's Campus.,National Institute for Health Research, Health Protection Research Unit in Respiratory Infections, Imperial College London
| | - Sarah Menzies
- Wexham Park Hospital, Slough, United Kingdom,Heatherwood Hospital, Frimley Health NHS Foundation Trust, Berkshire, UK
| | | | - Samuel Bremang
- Tuberculosis Research Centre, Respiratory Medicine, National Heart and Lung Institute, Imperial College London, St Mary's Campus
| | - Amarjit Badhan
- Tuberculosis Research Centre, Respiratory Medicine, National Heart and Lung Institute, Imperial College London, St Mary's Campus.,National Institute for Health Research, Health Protection Research Unit in Respiratory Infections, Imperial College London
| | - Peter Beverley
- Tuberculosis Research Centre, Respiratory Medicine, National Heart and Lung Institute, Imperial College London, St Mary's Campus
| | - Onn Min Kon
- Tuberculosis Research Centre, Respiratory Medicine, National Heart and Lung Institute, Imperial College London, St Mary's Campus.,National Institute for Health Research, Health Protection Research Unit in Respiratory Infections, Imperial College London.,St Mary's Hospital, Imperial NHS Healthcare, London
| | - Ajit Lalvani
- Tuberculosis Research Centre, Respiratory Medicine, National Heart and Lung Institute, Imperial College London, St Mary's Campus.,National Institute for Health Research, Health Protection Research Unit in Respiratory Infections, Imperial College London
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Hingley-Wilson SM, Connell D, Pollock K, Hsu T, Tchilian E, Sykes A, Grass L, Potiphar L, Bremang S, Kon OM, Jacobs WR, Lalvani A. ESX1-dependent fractalkine mediates chemotaxis and Mycobacterium tuberculosis infection in humans. Tuberculosis (Edinb) 2014; 94:262-70. [PMID: 24631198 PMCID: PMC4066952 DOI: 10.1016/j.tube.2014.01.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 01/09/2014] [Accepted: 01/27/2014] [Indexed: 11/28/2022]
Abstract
Mycobacterium tuberculosis-induced cellular aggregation is essential for granuloma formation and may assist establishment and early spread of M. tuberculosis infection. The M. tuberculosis ESX1 mutant, which has a non-functional type VII secretion system, induced significantly less production of the host macrophage-derived chemokine fractalkine (CX3CL1). Upon infection of human macrophages ESX1-dependent fractalkine production mediated selective recruitment of CD11b+ monocytic cells and increased infection of neighbouring cells consistent with early local spread of infection. Fractalkine levels were raised in vivo at tuberculous disease sites in humans and were significantly associated with increased CD11b+ monocytic cellular recruitment and extent of granulomatous disease. These findings suggest a novel fractalkine-dependent ESX1-mediated mechanism in early tuberculous disease pathogenesis in humans. Modulation of M. tuberculosis-mediated fractalkine induction may represent a potential treatment option in the future, perhaps allowing us to switch off a key mechanism required by the pathogen to spread between cells.
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Affiliation(s)
- Suzanne M Hingley-Wilson
- Tuberculosis Research Centre, Department of Respiratory Medicine, National Heart and Lung Institute, Imperial College London, London W2 1PG, United Kingdom.
| | - David Connell
- Tuberculosis Research Centre, Department of Respiratory Medicine, National Heart and Lung Institute, Imperial College London, London W2 1PG, United Kingdom
| | - Katrina Pollock
- Tuberculosis Research Centre, Department of Respiratory Medicine, National Heart and Lung Institute, Imperial College London, London W2 1PG, United Kingdom
| | - Tsungda Hsu
- Howard Hughes Medical Institute, Department of Microbiology and Immunology, Albert Einstein College of Medicine, New York, NY 10461, USA
| | - Elma Tchilian
- University of Oxford, Nuffield Department of Medicine, The Peter Medawar Building for Pathogen Research, South Parks Road, Oxford OX1 3SY, United Kingdom
| | - Anny Sykes
- Tuberculosis Service, St Mary's Hospital, Imperial College Healthcare, National Health Service Trust, London W2 1PG, United Kingdom
| | - Lisa Grass
- Tuberculosis Research Centre, Department of Respiratory Medicine, National Heart and Lung Institute, Imperial College London, London W2 1PG, United Kingdom
| | - Lee Potiphar
- Tuberculosis Research Centre, Department of Respiratory Medicine, National Heart and Lung Institute, Imperial College London, London W2 1PG, United Kingdom
| | - Samuel Bremang
- Tuberculosis Research Centre, Department of Respiratory Medicine, National Heart and Lung Institute, Imperial College London, London W2 1PG, United Kingdom
| | - Onn Min Kon
- Tuberculosis Service, St Mary's Hospital, Imperial College Healthcare, National Health Service Trust, London W2 1PG, United Kingdom
| | - William R Jacobs
- Howard Hughes Medical Institute, Department of Microbiology and Immunology, Albert Einstein College of Medicine, New York, NY 10461, USA
| | - Ajit Lalvani
- Tuberculosis Research Centre, Department of Respiratory Medicine, National Heart and Lung Institute, Imperial College London, London W2 1PG, United Kingdom
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Hingley-Wilson SM, Casey R, Connell D, Bremang S, Evans JT, Hawkey PM, Smith GE, Jepson A, Philip S, Kon OM, Lalvani A. Undetected multidrug-resistant tuberculosis amplified by first-line therapy in mixed infection. Emerg Infect Dis 2014; 19:1138-41. [PMID: 23764343 DOI: 10.3201/1907.130313] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Infections with >1 Mycobacterium tuberculosis strain(s) are underrecognized. We show, in vitro and in vivo, how first-line treatment conferred a competitive growth advantage to amplify a multidrug-resistant M. tuberculosis strain in a patient with mixed infection. Diagnostic techniques that identify mixed tubercle bacilli populations are needed to curb the spread of multidrug resistance.
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Hingley-Wilson SM, Casey R, Connell D, Bremang S, Evans JT, Hawkey PM, Smith GE, Jepson A, Philip S, Kon OM, Lalvani A. Undetected multidrug-resistant tuberculosis amplified by first-line therapy in mixed infection. Emerg Infect Dis 2014. [PMID: 23764343 PMCID: PMC3713993 DOI: 10.3201/eid1907.130313] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Infections with >1 Mycobacterium tuberculosis strain(s) are underrecognized. We show, in vitro and in vivo, how first-line treatment conferred a competitive growth advantage to amplify a multidrug-resistant M. tuberculosis strain in a patient with mixed infection. Diagnostic techniques that identify mixed tubercle bacilli populations are needed to curb the spread of multidrug resistance.
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Casey R, Blumenkrantz D, Millington K, Montamat-Sicotte D, Kon OM, Wickremasinghe M, Bremang S, Magtoto M, Sridhar S, Connell D, Lalvani A. Enumeration of functional T-cell subsets by fluorescence-immunospot defines signatures of pathogen burden in tuberculosis. PLoS One 2010; 5:e15619. [PMID: 21179481 PMCID: PMC3001879 DOI: 10.1371/journal.pone.0015619] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Accepted: 11/15/2010] [Indexed: 01/11/2023] Open
Abstract
Background IFN-γ and IL-2 cytokine-profiles define three functional T-cell subsets which may correlate with pathogen load in chronic intracellular infections. We therefore investigated the feasibility of the immunospot platform to rapidly enumerate T-cell subsets by single-cell IFN-γ/IL-2 cytokine-profiling and establish whether immunospot-based T-cell signatures distinguish different clinical stages of human tuberculosis infection. Methods We used fluorophore-labelled anti-IFN-γ and anti-IL-2 antibodies with digital overlay of spatially-mapped colour-filtered images to enumerate dual and single cytokine-secreting M. tuberculosis antigen-specific T-cells in tuberculosis patients and in latent tuberculosis infection (LTBI). We validated results against established measures of cytokine-secreting T-cells. Results Fluorescence-immunospot correlated closely with single-cytokine enzyme-linked-immunospot for IFN-γ-secreting T-cells and IL-2-secreting T-cells and flow-cytometry-based detection of dual IFN-γ/IL-2-secreting T-cells. The untreated tuberculosis signature was dominated by IFN-γ-only-secreting T-cells which shifted consistently in longitudinally-followed patients during treatment to a signature dominated by dual IFN-γ/IL-2-secreting T-cells in treated patients. The LTBI signature differed from active tuberculosis, with higher proportions of IL-2-only and IFN-γ/IL-2-secreting T-cells and lower proportions of IFN-γ-only-secreting T-cells. Conclusions Fluorescence-immunospot is a quantitative, accurate measure of functional T-cell subsets; identification of cytokine-signatures of pathogen burden, distinct clinical stages of M. tuberculosis infection and long-term immune containment suggests application for treatment monitoring and vaccine evaluation.
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Affiliation(s)
- Rosalyn Casey
- Tuberculosis Research Unit, Department of Respiratory Medicine, National Heart and Lung Institute, Imperial College London, St Mary's Hospital, London, United Kingdom
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