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Sannigrahi A, Chattopadhyay K. Pore formation by pore forming membrane proteins towards infections. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2021; 128:79-111. [PMID: 35034727 DOI: 10.1016/bs.apcsb.2021.09.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Over the last 25 years, the biology of membrane proteins, including the PFPs-membranes interactions is seeking attention for the development of successful drug molecules against a number of infectious diseases. Pore forming toxins (PFTs), the largest family of PFPs are considered as a group of virulence factors produced in a large number of pathogenic systems which include streptococcus, pneumonia, Staphylococcus aureus, E. coli, Mycobacterium tuberculosis, group A and B streptococci, Corynebacterium diphtheria and many more. PFTs are generally utilized by the disease causing pathogens to disrupt the host first line of defense i.e. host cell membranes through pore formation strategy. Although, pore formation is the principal mode of action of the PFTs but they can have additional adverse effects on the hosts including immune evasion. Recently, structural investigation of different PFTs have imparted the molecular mechanistic insights into how PFTs get transformed from its inactive state to active toxic state. On the basis of their structural entity, PFTs have been classified in different types and their mode of actions alters in terms of pore formation and corresponding cellular toxicity. Although pathogen genome analysis can identify the probable PFTs depending upon their structural diversity, there are so many PFTs which utilize the local environmental conditions to generate their pore forming ability using a novel strategy which is known as "conformational switch" of a protein. This conformational switch is considered as characteristics of the phase shifting proteins which were often utilized by many pathogenic systems to protect them from the invaders through allosteric communication between distant regions of the protein. In this chapter, we discuss the structure function relationships of PFTs and how activity of PFTs varies with the change in the environmental conditions has been explored. Finally, we demonstrate these structural insights to develop therapeutic potential to treat the infections caused by multidrug resistant pathogens.
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Affiliation(s)
- Achinta Sannigrahi
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru, Karnataka, India.
| | - Krishnananda Chattopadhyay
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, West Bengal, India.
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Duan Z, Li D, Jia Q, Xu J, Chen X, Xu Z, Liu H, Chen B, Wen J. The diagnostic potential of MPT63-derived HLA-A*0201-restricted CD8+ T-cell epitopes for active pulmonary tuberculosis. Microbiol Immunol 2015; 59:705-15. [PMID: 26577013 DOI: 10.1111/1348-0421.12339] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 11/10/2015] [Accepted: 11/11/2015] [Indexed: 12/23/2022]
Abstract
MPT63 protein is found only in Mycobacterium tuberculosis complex, including M. tuberculosis and M. bovis. Detection of MPT63-specific IFN-γ-secreting T cells could be useful for the diagnosis of tuberculosis (TB) diseases. In the present study, the HLA-A*0201 restriction of ten predicted MPT63-derived CD8(+) T-cell epitopes was assessed on the basis of T2 cell line and HLA-A*0201 transgenic mice. The diagnostic potential of immunogenic peptides in active pulmonary TB patients was evaluated using an IFN-γ enzyme-linked immunospot assay. It was found that five peptides bound to HLA-A*0201 with high affinity, whereas the remaining peptides exhibited low affinity for HLA-A*0201. Five immunogenic peptides (MPT6318-26 , MPT6329-37 , MPT6320-28 , MPT635-14 and MPT6310-19 ) elicited large numbers of cytotoxic IFN-γ-secreting T cells in HLA-A*0201 transgenic mice. Each of the five immunogenic peptides was recognized by peripheral blood mononuclear cells from 45% to 73% of 40 HLA-A*0201 positive TB patients. The total diagnostic sensitivity of the five immunogenic peptides was higher than that of a T-SPOT.TB assay (based on ESAT-6 and CFP-10) (93% versus 90%). It is noticeable that the diagnostic sensitivity of the combination of five immunogenic peptides and T-SPOT.TB assay reached 100%. These MPT63-derived HLA-A*0201-restricted CD8(+) T-cell epitopes would likely contribute to the immunological diagnosis of M. tuberculosis infection and may provide the components for designing an effective TB vaccine.
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Affiliation(s)
- Zhiliang Duan
- Department of Clinical Laboratory, Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Xueyuan West Road
| | - Dezhou Li
- Institute of Arboviruses, School of Basic Medical Sciences, Wenzhou Medical University, Chashan, Wenzhou 325000.,Department of Liver Disease, Second People's Hospital of Ningbo, Ningbo 315010
| | - Qingjun Jia
- Institute of Arboviruses, School of Basic Medical Sciences, Wenzhou Medical University, Chashan, Wenzhou 325000.,Department of Microbiology and Immunology, School of Basic Medical Sciences, Wenzhou Medical University, Chashan, Wenzhou 325000, China
| | - Juanjuan Xu
- Institute of Arboviruses, School of Basic Medical Sciences, Wenzhou Medical University, Chashan, Wenzhou 325000.,Department of Microbiology and Immunology, School of Basic Medical Sciences, Wenzhou Medical University, Chashan, Wenzhou 325000, China
| | - Xinyu Chen
- Department of Clinical Laboratory, Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Xueyuan West Road.,Institute of Arboviruses, School of Basic Medical Sciences, Wenzhou Medical University, Chashan, Wenzhou 325000
| | - Zhigang Xu
- Institute of Arboviruses, School of Basic Medical Sciences, Wenzhou Medical University, Chashan, Wenzhou 325000.,Department of Microbiology and Immunology, School of Basic Medical Sciences, Wenzhou Medical University, Chashan, Wenzhou 325000, China
| | - Huifang Liu
- Institute of Arboviruses, School of Basic Medical Sciences, Wenzhou Medical University, Chashan, Wenzhou 325000.,Department of Microbiology and Immunology, School of Basic Medical Sciences, Wenzhou Medical University, Chashan, Wenzhou 325000, China
| | - Bokun Chen
- Institute of Arboviruses, School of Basic Medical Sciences, Wenzhou Medical University, Chashan, Wenzhou 325000
| | - Jinsheng Wen
- Institute of Arboviruses, School of Basic Medical Sciences, Wenzhou Medical University, Chashan, Wenzhou 325000.,Department of Microbiology and Immunology, School of Basic Medical Sciences, Wenzhou Medical University, Chashan, Wenzhou 325000, China
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Mamani M, Majzoobi MM, Torabian S, Mihan R, Alizadeh K. Latent and active tuberculosis: evaluation of injecting drug users. IRANIAN RED CRESCENT MEDICAL JOURNAL 2013; 15:775-9. [PMID: 24616784 PMCID: PMC3929809 DOI: 10.5812/ircmj.6283] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 01/15/2013] [Accepted: 06/24/2013] [Indexed: 12/17/2022]
Abstract
Background There is a high risk of tuberculosis (TB) infection among injecting drug users (IDUs). Objectives This study aimed to determine the frequency of latent and active TB infection among IDUs. Materials and Methods In a cross-sectional study between 2008 and 2009, IDUs referred to the methadone maintenance treatment (MMT) centers in Hamedan-Iran, undergone tuberculin skin test (PPD; purified protein derivative) were recruited. The participants with positive results for PPD test (> 5 mm and > 10 mm in HIV positive and negative cases), undergone other complementary procedures such as chest-X-ray and sputum smear test. Results Overall, 268 IDUs between 18 and 70 (mean: 34.5 [8.2]) years were included in the study. PPD test had positive findings in 49 cases (18.3%). There was no significant difference of PPD positivity between HIV positive and negative participants (17.7% vs. 18.5%). An active TB was found among IDUs. Conclusions The high prevalence of latent and active TB among IDUs indicates the need for TB screening tests among this population.
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Affiliation(s)
- Mojgan Mamani
- Department of Infectious Diseases, Hamedan University of Medical Sciences, Hamedan, IR Iran
| | - Mohammad Mahdi Majzoobi
- Department of Infectious Diseases, Hamedan University of Medical Sciences, Hamedan, IR Iran
- Corresponding author: Mohammad Mahdi Majzoobi, Division of Infectious Diseases, Farshchian Hospital, Hamedan, IR Iran. Tel.: +98-9183148151, Fax: +98-8118269808, E-mail:
| | - Saadat Torabian
- Department of Social Medicine, Hamedan University of Medical Sciences, Hamedan, IR Iran
| | - Ronak Mihan
- Hamedan University of Medical Sciences, Hamedan, IR Iran
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Assessment of a protein cocktail-based skin test for bovine tuberculosis in a double-blind field test in cattle. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2013; 20:482-90. [PMID: 23365203 DOI: 10.1128/cvi.00592-12] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Bovine tuberculosis (bTB) is a worldwide zoonosis caused mainly by Mycobacterium bovis. The traditional diagnostic method used often is the tuberculin skin test, which uses bovine purified protein derivatives (PPD-B). However, it is difficult to maintain uniformity of PPD-B from batch to batch, and it shares common antigens with nonpathogenic environmental mycobacteria. To overcome these problems, M. bovis-specific antigens that showed good T cell stimulation, such as CFP-10, ESAT-6, Rv3615c, etc., have been used in the skin test, but there have been no large-scale clinical studies on these antigens. In this study, two combinations (CFP-10/ESAT-6/TB10.4 protein cocktail and CFP-10/ESAT-6/Rv3872/MPT63 protein cocktail) were developed and used as stimuli in the skin test. Cattle were double-blind tested to assess the efficiency of the protein cocktail-based skin tests. The results showed that the CFP-10/ESAT-6/TB10.4 protein cocktail-based skin test can differentiate TB-infected cattle from Mycobacterium avium-infected ones and that it shows a high degree of agreement with the traditional tuberculin skin test (κ = 0.8536) and gamma interferon (IFN-γ) release assay (κ = 0.8154). Compared to the tuberculin skin test, the relative sensitivity and relative specificity of the CFP-10/ESAT-6/TB10.4-based skin test were 87% and 97%, respectively., The relative sensitivity and relative specificity of the CFP-10/ESAT-6/TB10.4-based skin test were 93% and 92%, respectively, on comparison with the IFN-γ release assay. The correlation between the increases in skin thickness observed after the inoculation of stimuli was high (PPD-B versus CFP-10/ESAT-6/TB10.4, Spearman r of 0.8435). The correlation between the optical density at 450 nm (OD450) obtained after blood stimulation with PPD-B and the increase in skin thickness observed after inoculation of the CFP-10/ESAT-6/TB10.4 protein cocktail was high (Spearman r = 0.7335). Therefore, the CFP-10/ESAT-6/TB10.4-based skin test responses correlate to traditional measures of bovine TB evaluation, including skin test and gamma interferon release assay.
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Kim YJ, Kim SI, Kim YR, Wie SH, Park YJ, Kang MW. Predictive value of interferon-γ ELISPOT assay in HIV 1-infected patients in an intermediate tuberculosis-endemic area. AIDS Res Hum Retroviruses 2012; 28:1038-43. [PMID: 22352311 DOI: 10.1089/aid.2011.0360] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The tuberculin skin test for diagnosing latent tuberculosis (TB) has some limitations for HIV-infected patients, especially in BCG vaccinated countries. The objective of this study was to identify the incidence rate of new TB cases among HIV-infected patients in an intermediate TB-endemic area and to examine its correlation with the ELISPOT assay. We prospectively followed up 124 patients with HIV-1 infection to monitor development of active TB disease after performing an ELISPOT assay (T-SPOT. TB test, Oxford Immunotec, Ltd., Abingdon, UK). A total of 120 patients were followed for a median of 947 days; four patients with active TB at enrollment were excluded. Eleven patients developed active TB during 238 person-years, giving a high incidence rate of 4621/100,000 person-years. Patients with positive ELISPOT responses had a higher TB incidence rate than those with negative ELISPOT responses; however this was not statistically significant [20% (6/30) vs. 6.02% (5/83), p=0.052]. A Cox regression analysis showed that the independent risk factors associated with progression of TB were low CD4(+) T cell counts, previous history of TB treatment, and positive ELISPOT results. Advanced HIV-infected patients who showed a positive TB ELISPOT assay had a higher rate of progression to TB in the intermediate TB-endemic area.
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Affiliation(s)
- Youn Jeong Kim
- Division of Infectious Diseases, Department of Internal Medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea
| | - Sang Il Kim
- Division of Infectious Diseases, Department of Internal Medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea
| | - Yang Ree Kim
- Division of Infectious Diseases, Department of Internal Medicine, Uijeongbu St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea
| | - Seong Heon Wie
- Division of Infectious Diseases, Department of Internal Medicine, St. Vincent Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea
| | - Yeon Joon Park
- Laboratory Medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea
| | - Moon Won Kang
- Division of Infectious Diseases, Department of Internal Medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea
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Alsleben N, Ruhwald M, Rüssmann H, Marx FM, Wahn U, Magdorf K. Interferon-gamma inducible protein 10 as a biomarker for active tuberculosis and latent tuberculosis infection in children: a case-control study. ACTA ACUST UNITED AC 2011; 44:256-62. [PMID: 22103555 DOI: 10.3109/00365548.2011.632644] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND Interferon-gamma (IFN-γ) release assays (IGRAs) are suboptimally sensitive to diagnose tuberculosis (TB) and latent TB infection (LTBI) in young children. In this study we compared Mycobacterium tuberculosis antigen-stimulated IFN-γ inducible protein 10 (IP-10) responses in children with active TB and LTBI to responses from children with non-tuberculous mycobacterial (NTM) lymphadenopathy and respiratory tract infection (RTI). We also assessed test agreement between IP-10 and the QuantiFERON(®)-TB Gold In-Tube (QFT-IT) test results, and investigated whether IP-10 release upon mitogen stimulation is associated with age. METHODS We recruited 48 children (median age 54 months) diagnosed in Germany with either active TB (n = 11), LTBI (n = 14), NTM lymphadenopathy (n = 8), or common RTI (n = 15). IFN-γ levels were measured using the QFT-IT. These plasma supernatants were used to determine IP-10 concentrations using an in-house enzyme-linked immunosorbent assay (ELISA). RESULTS The median antigen-stimulated IP-10 levels in children with active TB, LTBI, NTM lymphadenopathy, and RTI were 12,702 pg/ml, 9109 pg/ml, 97 pg/ml, and 84 pg/ml, respectively. We observed a strong correlation between IP-10 and IFN-γ plasma concentration in children with active TB and LTBI (r(2) = 0.69). Overall agreement between IP-10 and QFT-IT assays was high (kappa = 0.95). IP-10 levels after mitogen stimulation showed no association with age. CONCLUSIONS IP-10 and IFN-γ were both induced with antigen stimulation in blood from children in the TB and LTBI groups, in contrast to the NTM and RTI groups. Compared to IFN-γ the IP-10 levels were higher and IP-10 was released independently of age. IP-10 therefore may represent an additional biomarker in the paediatric population.
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Affiliation(s)
- Neele Alsleben
- Department of Paediatric Pneumology and Immunology, Charité Universitätsmedizin Berlin, Berlin, Germany.
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Magdorf K, Schuck S, Leitner S, Wahn U, Kaufmann S, Jacobsen M. T-cell responses against tuberculin and sensitin in children with tuberculosis and non-tuberculosis mycobacterial lymphadenopathy. Clin Microbiol Infect 2008; 14:1079-83. [DOI: 10.1111/j.1469-0691.2008.02084.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Jafari C, Ernst M, Kalsdorf B, Greinert U, Diel R, Kirsten D, Marienfeld K, Lalvani A, Lange C. Rapid diagnosis of smear-negative tuberculosis by bronchoalveolar lavage enzyme-linked immunospot. Am J Respir Crit Care Med 2006; 174:1048-54. [PMID: 16858013 DOI: 10.1164/rccm.200604-465oc] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE In a large proportion of patients with active pulmonary tuberculosis (pTB), acid-fast bacilli smear results for sputum and bronchial secretions are negative. Detectable growth of Mycobacterium tuberculosis (MTB) in cultures takes several weeks and MTB-specific DNA amplification results on sputum and bronchial secretions are variable in these patients. OBJECTIVE We investigated whether a rapid diagnosis of pTB can be established by enumeration of MTB-specific mononuclear cells from bronchoalveolar lavage (BAL) fluid in routine clinical practice. METHODS Patients presenting to a tertiary hospital with medical histories and pulmonary infiltrates compatible with tuberculosis, and negative acid-fast bacilli smear results (three) from sputum, were prospectively enrolled in this study. An MTB-specific enzyme-linked immunospot assay (ELISPOT [T-SPOT.TB; Oxford Immunotec, Abingdon, UK]) with early antigenic target-6 (ESAT-6) and culture filtrate protein-10 (CFP-10) peptides was performed on peripheral blood mononuclear cells (PBMCs) and mononuclear cells from the BAL fluid (BALMCs). MEASUREMENTS AND MAIN RESULTS Of 37 patients, 12 were found to have smear-negative pTB and 25 were found to have an alternative diagnosis. Patients with tuberculosis had a median number of 17 ESAT-6-specific cells and 24.5 CFP-10-specific cells per 200,000 PBMCs and 37.5 ESAT-6-specific cells and 49.5 CFP-10-specific cells per 200,000 cells in the BAL fluid. Control patients had a median of 1 ESAT-6-specific cell and 1 CFP-10-specific cell per 200,000 PBMCs and no ESAT-6- and CFP-10-specific cells per 200,000 cells in the BAL fluid (p < 0.0001). All patients with TB but none of the control subjects had more than 5 spot-forming cells per 200,000 BALMCs with either peptide in the BAL fluid ELISPOT. CONCLUSION Smear-negative pulmonary tuberculosis can be diagnosed rapidly by identification of MTB-specific cells in the BAL fluid.
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Affiliation(s)
- Claudia Jafari
- Division of Clinical Infectious Diseases, Research Center Borstel, Parkallee 35, Borstel, Germany
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Brock I, Ruhwald M, Lundgren B, Westh H, Mathiesen LR, Ravn P. Latent tuberculosis in HIV positive, diagnosed by the M. tuberculosis specific interferon-gamma test. Respir Res 2006; 7:56. [PMID: 16579856 PMCID: PMC1523341 DOI: 10.1186/1465-9921-7-56] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Accepted: 04/01/2006] [Indexed: 11/12/2022] Open
Abstract
Background Although tuberculosis (TB) is a minor problem in Denmark, severe and complicated cases occur in HIV positive. Since the new M. tuberculosis specific test for latent TB, the QuantiFERON-TB In-Tube test (QFT-IT) became available the patients in our clinic have been screened for the presence of latent TB using the QFT-IT test. We here report the results from the first patients screened. Methods On a routine basis the QFT-IT test was performed and the results from 590 HIV positive individuals consecutively tested are presented here. CD4 cell count and TB risk-factors were recorded from patient files. Main findings 27/590(4.6%) of the individuals were QFT-IT test positive, indicating the presence of latent TB infection. Among QFT-IT positive patients, 78% had risk factors such as long-term residency in a TB high endemic area (OR:5.7), known TB exposure (OR:4.9) or previous TB disease (OR:4.9). The prevalence of latent TB in these groups were 13%, 16% and 19% respectively. There was a strong correlation between low CD4 T-cell count and a low mitogen response (P < 0.001;Spearman) and more patients with low CD4 cell count had indeterminate results. Conclusion We found an overall prevalence of latent TB infection of 4.6% among the HIV positive individuals and a much higher prevalence of latent infection among those with a history of exposure (16%) and long term residency in a high endemic country (13%). The QFT-IT test may indeed be a useful test for HIV positive individuals, but in severely immunocompromised, the test may be impaired by T-cell anergy.
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Affiliation(s)
- Inger Brock
- Department for Clinical Microbiology, University Hospital, Hvidovre 2650, Denmark
| | - Morten Ruhwald
- Department for Infectious Diseases, University Hospital, Hvidovre 2650, Denmark
| | - Bettina Lundgren
- Department for Clinical Microbiology, University Hospital, Hvidovre 2650, Denmark
| | - Henrik Westh
- Department for Clinical Microbiology, University Hospital, Hvidovre 2650, Denmark
| | - Lars R Mathiesen
- Department for Infectious Diseases, University Hospital, Hvidovre 2650, Denmark
| | - Pernille Ravn
- Department for Infectious Diseases, University Hospital, Hvidovre 2650, Denmark
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Detjen A, Wahn U, Magdorf K. Immunologische Diagnostik der Tuberkulose — Interferon-γ-Tests. Monatsschr Kinderheilkd 2006. [DOI: 10.1007/s00112-005-1288-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Pai M, Riley LW, Colford JM. Interferon-γ assays in the immunodiagnosis of tuberculosis: a systematic review. THE LANCET. INFECTIOUS DISEASES 2004; 4:761-76. [PMID: 15567126 DOI: 10.1016/s1473-3099(04)01206-x] [Citation(s) in RCA: 631] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
A major challenge in tuberculosis control is the diagnosis and treatment of latent tuberculosis infection. Until recently, there were no alternatives to the tuberculin skin test (TST) for diagnosing latent tuberculosis. However, an alternative has now emerged in the form of a new in-vitro test: the interferon-gamma assay. We did a systematic review to assess the performance of interferon-gamma assays in the immunodiagnosis of tuberculosis. By searching databases, contacting experts and test manufacturers, we identified 75 relevant studies. The results suggest that interferon-gamma assays that use Mycobacterium tuberculosis-specific region of difference 1 (RD1) antigens (such as early secretory antigenic target 6 and culture filtrate protein 10) may have advantages over the TST, in terms of higher specificity, better correlation with exposure to M tuberculosis, and less cross-reactivity due to BCG vaccination and non-tuberculous mycobacterial infection. However, interferon-gamma assays that use RD1 antigens in isolation may maximise specificity at the cost of sensitivity. Assays that use cocktails of RD1 antigens seem to overcome this problem, and such assays have the highest accuracy. RD1-based interferon-gamma assays can potentially identify those with latent tuberculosis who are at high risk for developing active disease, but this requires confirmation. There is inadequate evidence on the value of interferon-gamma assays in the management of immunocompromised individuals, children, patients with extrapulmonary or non-tuberculous mycobacterial disease, and populations in countries where tuberculosis is endemic. Current evidence suggests that interferon-gamma assays based on cocktails of RD1 antigens have the potential to become useful diagnostic tools. Whether this potential can be realised in practice remains to be confirmed in well designed, long-term studies.
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Affiliation(s)
- Madhukar Pai
- Division of Epidemiology, School of Public Health, University of California, Berkeley, CA, USA.
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