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Wang J, Jiang F, Cheng P, Ye Z, Li L, Yang L, Zhuang L, Gong W. Construction of novel multi-epitope-based diagnostic biomarker HP16118P and its application in the differential diagnosis of Mycobacterium tuberculosis latent infection. MOLECULAR BIOMEDICINE 2024; 5:15. [PMID: 38679629 PMCID: PMC11056354 DOI: 10.1186/s43556-024-00177-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 02/29/2024] [Indexed: 05/01/2024] Open
Abstract
Tuberculosis (TB) is an infectious disease that significantly threatens human health. However, the differential diagnosis of latent tuberculosis infection (LTBI) and active tuberculosis (ATB) remains a challenge for clinicians in early detection and preventive intervention. In this study, we developed a novel biomarker named HP16118P, utilizing 16 helper T lymphocyte (HTL) epitopes, 11 cytotoxic T lymphocyte (CTL) epitopes, and 8 B cell epitopes identified from 15 antigens associated with LTBI-RD using the IEDB database. We analyzed the physicochemical properties, spatial structure, and immunological characteristics of HP16118P using various tools, which indicated that it is a hydrophilic and relatively stable alkaline protein. Furthermore, HP16118P exhibited good antigenicity and immunogenicity, while being non-toxic and non-allergenic, with the potential to induce immune responses. We observed that HP16118P can stimulate the production of high levels of IFN-γ+ T lymphocytes in individuals with ATB, LTBI, and health controls. IL-5 induced by HP16118P demonstrated potential in distinguishing LTBI individuals and ATB patients (p=0.0372, AUC=0.8214, 95% CI [0.5843 to 1.000]) with a sensitivity of 100% and specificity of 71.43%. Furthermore, we incorporated the GM-CSF, IL-23, IL-5, and MCP-3 induced by HP16118P into 15 machine learning algorithms to construct a model. It was found that the Quadratic discriminant analysis model exhibited the best diagnostic performance for discriminating between LTBI and ATB, with a sensitivity of 1.00, specificity of 0.86, and accuracy of 0.93. In summary, HP16118P has demonstrated strong antigenicity and immunogenicity, with the induction of GM-CSF, IL-23, IL-5, and MCP-3, suggesting their potential for the differential diagnosis of LTBI and ATB.
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Affiliation(s)
- Jie Wang
- Beijing Key Laboratory of New Techniques of Tuberculosis Diagnosis and Treatment, Institute of Tuberculosis Research, Senior Department of Tuberculosis, The Eighth Medical Center of PLA General Hospital, 17#Heishanhu Road, Haidian District, Beijing, 100091, China
- Department of Clinical Laboratory, The Eighth Medical Center of PLA General Hospital, Beijing, 100091, China
| | - Fan Jiang
- Beijing Key Laboratory of New Techniques of Tuberculosis Diagnosis and Treatment, Institute of Tuberculosis Research, Senior Department of Tuberculosis, The Eighth Medical Center of PLA General Hospital, 17#Heishanhu Road, Haidian District, Beijing, 100091, China
- Section of Health, No. 94804 Unit of the Chinese People's Liberation Army, Shanghai, 200434, China
- Resident standardization training cadet corps, Air Force Hospital of Eastern Theater, Nanjing, 210002, China
| | - Peng Cheng
- Beijing Key Laboratory of New Techniques of Tuberculosis Diagnosis and Treatment, Institute of Tuberculosis Research, Senior Department of Tuberculosis, The Eighth Medical Center of PLA General Hospital, 17#Heishanhu Road, Haidian District, Beijing, 100091, China
| | - Zhaoyang Ye
- Beijing Key Laboratory of New Techniques of Tuberculosis Diagnosis and Treatment, Institute of Tuberculosis Research, Senior Department of Tuberculosis, The Eighth Medical Center of PLA General Hospital, 17#Heishanhu Road, Haidian District, Beijing, 100091, China
- Hebei North University, ZhangjiakouHebei, 075000, China
| | - Linsheng Li
- Beijing Key Laboratory of New Techniques of Tuberculosis Diagnosis and Treatment, Institute of Tuberculosis Research, Senior Department of Tuberculosis, The Eighth Medical Center of PLA General Hospital, 17#Heishanhu Road, Haidian District, Beijing, 100091, China
- Hebei North University, ZhangjiakouHebei, 075000, China
| | - Ling Yang
- Beijing Key Laboratory of New Techniques of Tuberculosis Diagnosis and Treatment, Institute of Tuberculosis Research, Senior Department of Tuberculosis, The Eighth Medical Center of PLA General Hospital, 17#Heishanhu Road, Haidian District, Beijing, 100091, China
- Hebei North University, ZhangjiakouHebei, 075000, China
| | - Li Zhuang
- Beijing Key Laboratory of New Techniques of Tuberculosis Diagnosis and Treatment, Institute of Tuberculosis Research, Senior Department of Tuberculosis, The Eighth Medical Center of PLA General Hospital, 17#Heishanhu Road, Haidian District, Beijing, 100091, China
- Hebei North University, ZhangjiakouHebei, 075000, China
| | - Wenping Gong
- Beijing Key Laboratory of New Techniques of Tuberculosis Diagnosis and Treatment, Institute of Tuberculosis Research, Senior Department of Tuberculosis, The Eighth Medical Center of PLA General Hospital, 17#Heishanhu Road, Haidian District, Beijing, 100091, China.
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Anand PK, Kaur G, Saini V, Kaur J, Kaur J. N-terminal PPE domain plays an integral role in extracellular transportation and stability of the immunomodulatory Rv3539 protein of the Mycobacterium tuberculosis. Biochimie 2023; 213:30-40. [PMID: 37156406 DOI: 10.1016/j.biochi.2023.05.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Revised: 03/31/2023] [Accepted: 05/05/2023] [Indexed: 05/10/2023]
Abstract
Multigene PE/PPE family is exclusively present in mycobacterium species. Only few selected genes of this family have been characterized till date. Rv3539 was annotated as PPE63 with conserved PPE domain at N-terminal and PE-PPE at C-terminal. An α/β hydrolase structural fold, characteristic of lipase/esterase, was present in the PE-PPE domain. To assign the biochemical function to Rv3539, the corresponding gene was cloned in pET-32a (+) as full-length, PPE, and PE-PPE domains individually, followed by expression in E. Coli C41 (DE3). All three proteins demonstrated esterase activity. However, the enzyme activity in the N-terminal PPE domain was very low. The enzyme activity of Rv3539 and PE-PPE proteins was approximately same with the pNP-C4 as optimum substrate at 40 °C and pH 8.0. The loss of enzyme activity after mutating the predicted catalytic triad (Ser296Ala, Asp369Ala, and His395Ala) found only in the PE-PPE domain, confirmed the candidature of the bioinformatically predicted active site residue. The optimal activity and thermostability of the Rv3539 protein was altered by removing the PPE domain. CD-spectroscopy analysis confirmed the role of PPE domain to the thermostability of Rv3539 by maintaining the structural integrity at higher temperatures. The presence of the N-terminal PPE domain directed the Rv3539 protein to the cell membrane/wall and the extracellular compartment. The Rv3539 protein could generate humoral response in TB patients. Therefore, results demonstrated that Rv3539 demonstrated esterase activity. PE-PPE domain of Rv3539 is functionally automated, however, N-terminus domain played a role in protein stabilization and its transportation. Both domains participated in immunomodulation.
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Affiliation(s)
- Pradeep Kumar Anand
- Department of Biotechnology, BMS Block-1, South Campus, Panjab University, Chandigarh, 160014, India.
| | - Gagandeep Kaur
- Department of Biotechnology, BMS Block-1, South Campus, Panjab University, Chandigarh, 160014, India.
| | - Varinder Saini
- Department of Pulmonary Medicine, Government Medical College and Hospital, Chandigarh, India.
| | - Jasbinder Kaur
- Department of Biochemistry, Government Medical College and Hospital, Chandigarh, India.
| | - Jagdeep Kaur
- Department of Biotechnology, BMS Block-1, South Campus, Panjab University, Chandigarh, 160014, India.
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Guo F, Wei J, Song Y, Li B, Qian Z, Wang X, Wang H, Xu T. Immunological effects of the PE/PPE family proteins of Mycobacterium tuberculosis and related vaccines. Front Immunol 2023; 14:1255920. [PMID: 37841250 PMCID: PMC10569470 DOI: 10.3389/fimmu.2023.1255920] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 08/25/2023] [Indexed: 10/17/2023] Open
Abstract
Tuberculosis (TB) is a chronic infectious disease caused by Mycobacterium tuberculosis (Mtb), and its incidence and mortality are increasing. The BCG vaccine was developed in the early 20th century. As the most widely administered vaccine in the world, approximately 100 million newborns are vaccinated with BCG every year, which has saved tens of millions of lives. However, due to differences in region and race, the average protective rate of BCG in preventing tuberculosis in children is still not high in some areas. Moreover, because the immune memory induced by BCG will weaken with the increase of age, it is slightly inferior in preventing adult tuberculosis, and BCG revaccination cannot reduce the incidence of tuberculosis again. Research on the mechanism of Mtb and the development of new vaccines against TB are the main strategies for preventing and treating TB. In recent years, Pro-Glu motif-containing (PE) and Pro-Pro-Glu motif-containing (PPE) family proteins have been found to have an increasingly important role in the pathogenesis and chronic protracted infection observed in TB. The development and clinical trials of vaccines based on Mtb antigens are in progress. Herein, we review the immunological effects of PE/PPE proteins and the development of common PE/PPE vaccines.
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Affiliation(s)
- Fangzheng Guo
- Research Center of Laboratory, Bengbu Medical College, Bengbu, China
- Anhui Province Key Laboratory of Immunology in Chronic Diseases , Bengbu Medical College, Bengbu, China
| | - Jing Wei
- Research Center of Laboratory, Bengbu Medical College, Bengbu, China
- Anhui Province Key Laboratory of Immunology in Chronic Diseases , Bengbu Medical College, Bengbu, China
| | - Yamin Song
- Research Center of Laboratory, Bengbu Medical College, Bengbu, China
- Anhui Province Key Laboratory of Immunology in Chronic Diseases , Bengbu Medical College, Bengbu, China
| | - Baiqing Li
- Research Center of Laboratory, Bengbu Medical College, Bengbu, China
- Anhui Province Key Laboratory of Immunology in Chronic Diseases , Bengbu Medical College, Bengbu, China
- Department of Immunology, School of Laboratory, Bengbu Medical College, Bengbu, China
| | - Zhongqing Qian
- Research Center of Laboratory, Bengbu Medical College, Bengbu, China
- Anhui Province Key Laboratory of Immunology in Chronic Diseases , Bengbu Medical College, Bengbu, China
- Department of Immunology, School of Laboratory, Bengbu Medical College, Bengbu, China
| | - Xiaojing Wang
- Anhui Province Key Laboratory of Clinical and Preclinical Research in Respiratory Disease, Bengbu Medical College, Bengbu, China
| | - Hongtao Wang
- Research Center of Laboratory, Bengbu Medical College, Bengbu, China
- Anhui Province Key Laboratory of Immunology in Chronic Diseases , Bengbu Medical College, Bengbu, China
- Department of Immunology, School of Laboratory, Bengbu Medical College, Bengbu, China
| | - Tao Xu
- Research Center of Laboratory, Bengbu Medical College, Bengbu, China
- Anhui Province Key Laboratory of Immunology in Chronic Diseases , Bengbu Medical College, Bengbu, China
- Department of Clinical Laboratory, School of Laboratory, Bengbu Medical College, Bengbu, China
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D'Souza C, Kishore U, Tsolaki AG. The PE-PPE Family of Mycobacterium tuberculosis: Proteins in Disguise. Immunobiology 2023; 228:152321. [PMID: 36805109 DOI: 10.1016/j.imbio.2022.152321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 12/22/2022] [Accepted: 12/27/2022] [Indexed: 12/31/2022]
Abstract
Mycobacterium tuberculosis has thrived in parallel with humans for millennia, and despite our efforts, M. tuberculosis continues to plague us, currently infecting a third of the world's population. The success of M. tuberculosis has recently been attributed, in part, to the PE-PPE family; a unique collection of 168 proteins fundamentally involved in the pathogenesis of M. tuberculosis. The PE-PPE family proteins have been at the forefront of intense research efforts since their discovery in 1998 and whilst our knowledge and understanding has significantly advanced over the last two decades, many important questions remain to be elucidated. This review consolidates and examines the vast body of existing literature regarding the PE-PPE family proteins, with respect to the latest developments in elucidating their evolution, structure, subcellular localisation, function, and immunogenicity. This review also highlights significant inconsistencies and contradictions within the field. Additionally, possible explanations for these knowledge gaps are explored. Lastly, this review poses many important questions, which need to be addressed to complete our understanding of the PE-PPE family, as well as highlighting the challenges associated with studying this enigmatic family of proteins. Further research into the PE-PPE family, together with technological advancements in genomics and proteomics, will undoubtedly improve our understanding of the pathogenesis of M. tuberculosis, as well as identify key targets/candidates for the development of novel drugs, diagnostics, and vaccines.
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Affiliation(s)
- Christopher D'Souza
- Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge UB8 3PH, United Kingdom
| | - Uday Kishore
- Department of Veterinary Medicine, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Anthony G Tsolaki
- Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge UB8 3PH, United Kingdom.
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Arif S, Akhter M, Khaliq A, Akhtar MW. Fusion peptide constructs from antigens of M. tuberculosis producing high T-cell mediated immune response. PLoS One 2022; 17:e0271126. [PMID: 36174012 PMCID: PMC9521936 DOI: 10.1371/journal.pone.0271126] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Accepted: 06/23/2022] [Indexed: 11/18/2022] Open
Abstract
Non availability of effective anti-TB vaccine impedes TB control which remains a crucial global health issue. A fusion molecule based on immunogenic antigens specific to different growth phases of Mycobacterium tuberculosis can enhance T-cell responses required for developing a potent vaccine. In this study, six antigens including EspC, TB10.4, HspX, PPE57, CFP21 and Rv1352 were selected for constructing EspC-TB10.4 (bifu25), TnCFP21-Rv1352 (bifu29), HspX-EspC-TB10.4 (trifu37), HspX-TnCFP21-Rv1352 (trifu44) and HspX-EspC-TB10.4-PPE57 (tetrafu56) fusion proteins. Th1-cell epitopes of EspC, PPE57 and Rv1352 antigens were predicted for the first time using different in silico tools. The fusion molecule tetrafu56, which consisted of antigens from both the replicating and the dormant stages of Mtb, induced a release of 397 pg/mL of IFN-γ from PBMCs of the active TB patients. This response was comparable to the response obtained with cocktail of the component antigens (396 pg/mL) as well as to the total of the responses obtained separately for each of its component antigens (388 pg/mL). However, PBMCs from healthy samples in response to tetrafu56 showed IFN-γ release of only 26.0 pg/mL Thus a previous exposure of PBMCs to Mtb antigens in TB plasma samples resulted in 15-fold increase in IFN-γ response to tetrafu56 as compared to the PBMCs from the healthy controls. Hence, most of the T-cell epitopes of the individual antigens seem to be available for T-cell interactions in the form of the fusion. Further investigation in animal models should substantiate the immune efficacy of the fusion molecule. Thus, the fusion tetrafu56 seems to be a potential candidate for developing an effective multistage vaccine against TB.
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Affiliation(s)
- Shaista Arif
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan
| | - Mohsina Akhter
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan
| | - Aasia Khaliq
- Department of Biology, Lahore University of Management Sciences (LUMS), Lahore, Pakistan
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Gong W, Wu X. Differential Diagnosis of Latent Tuberculosis Infection and Active Tuberculosis: A Key to a Successful Tuberculosis Control Strategy. Front Microbiol 2021; 12:745592. [PMID: 34745048 PMCID: PMC8570039 DOI: 10.3389/fmicb.2021.745592] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 09/24/2021] [Indexed: 12/16/2022] Open
Abstract
As an ancient infectious disease, tuberculosis (TB) is still the leading cause of death from a single infectious agent worldwide. Latent TB infection (LTBI) has been recognized as the largest source of new TB cases and is one of the biggest obstacles to achieving the aim of the End TB Strategy. The latest data indicate that a considerable percentage of the population with LTBI and the lack of differential diagnosis between LTBI and active TB (aTB) may be potential reasons for the high TB morbidity and mortality in countries with high TB burdens. The tuberculin skin test (TST) has been used to diagnose TB for > 100 years, but it fails to distinguish patients with LTBI from those with aTB and people who have received Bacillus Calmette–Guérin vaccination. To overcome the limitations of TST, several new skin tests and interferon-gamma release assays have been developed, such as the Diaskintest, C-Tb skin test, EC-Test, and T-cell spot of the TB assay, QuantiFERON-TB Gold In-Tube, QuantiFERON-TB Gold-Plus, LIAISON QuantiFERON-TB Gold Plus test, and LIOFeron TB/LTBI. However, these methods cannot distinguish LTBI from aTB. To investigate the reasons why all these methods cannot distinguish LTBI from aTB, we have explained the concept and definition of LTBI and expounded on the immunological mechanism of LTBI in this review. In addition, we have outlined the research status, future directions, and challenges of LTBI differential diagnosis, including novel biomarkers derived from Mycobacterium tuberculosis and hosts, new models and algorithms, omics technologies, and microbiota.
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Affiliation(s)
- Wenping Gong
- Tuberculosis Prevention and Control Key Laboratory/Beijing Key Laboratory of New Techniques of Tuberculosis Diagnosis and Treatment, Senior Department of Tuberculosis, The 8th Medical Center of PLA General Hospital, Beijing, China
| | - Xueqiong Wu
- Tuberculosis Prevention and Control Key Laboratory/Beijing Key Laboratory of New Techniques of Tuberculosis Diagnosis and Treatment, Senior Department of Tuberculosis, The 8th Medical Center of PLA General Hospital, Beijing, China
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Yi F, Hu J, Zhu X, Wang Y, Yu Q, Deng J, Huang X, Ma Y, Xie Y. Transcriptional Profiling of Human Peripheral Blood Mononuclear Cells Stimulated by Mycobacterium tuberculosis PPE57 Identifies Characteristic Genes Associated With Type I Interferon Signaling. Front Cell Infect Microbiol 2021; 11:716809. [PMID: 34490145 PMCID: PMC8416891 DOI: 10.3389/fcimb.2021.716809] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Accepted: 07/30/2021] [Indexed: 02/05/2023] Open
Abstract
Proline-glutamic acid (PE)- and proline-proline-glutamic acid (PPE)-containing proteins are exclusive to Mycobacterium tuberculosis (MTB), the leading cause of tuberculosis (TB). In this study, we performed global transcriptome sequencing (RNA-Seq) on PPE57-stimulated peripheral blood mononuclear cells (PBMCs) and control samples to quantitatively measure the expression level of key transcripts of interest. A total of 1367 differentially expressed genes (DEGs) were observed in response to a 6 h exposure to PPE57, with 685 being up-regulated and 682 down-regulated. Immune-related gene functions and pathways associated with these genes were evaluated, revealing that the type I IFN signaling pathway was the most significantly enriched pathway in our RNA-seq dataset, with 14 DEGs identified therein including ISG15, MX2, IRF9, IFIT3, IFIT2, OAS3, IFIT1, IFI6, OAS2, OASL, RSAD2, OAS1, IRF7, and MX1. These PPE57-related transcriptomic profiles have implications for a better understanding of host global immune mechanisms underlying MTB infection outcomes. However, more studies regarding these DEGs and type I IFN signaling in this infectious context are necessary to more fully clarify the underlying mechanisms that arise in response to PPE57 during MTB infection.
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Affiliation(s)
- Fanli Yi
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Jing Hu
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Xiaoyan Zhu
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Yue Wang
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Qiuju Yu
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Jing Deng
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Xuedong Huang
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Ying Ma
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Yi Xie
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, China
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Srivastava S, Abraham PR, Mukhopadhyay S. Aptamers: An Emerging Tool for Diagnosis and Therapeutics in Tuberculosis. Front Cell Infect Microbiol 2021; 11:656421. [PMID: 34277465 PMCID: PMC8280756 DOI: 10.3389/fcimb.2021.656421] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 06/09/2021] [Indexed: 11/13/2022] Open
Abstract
Tuberculosis (TB) has been plaguing human civilization for centuries, and currently around one-third of the global population is affected with TB. Development of novel intervention tools for early diagnosis and therapeutics against Mycobacterium tuberculosis (M.tb) is the main thrust area in today's scenario. In this direction global efforts were made to use aptamers, the chemical antibodies as tool for TB diagnostics and therapeutics. This review describes the various aptamers introduced for targeting M.tb and highlights the need for development of novel aptamers to selectively target virulent proteins of M.tb for vaccine and anti-TB drugs. The objective of this review is to highlight the diagnostic and therapeutic application of aptamers used for tuberculosis. The discovery of aptamers, SELEX technology, different types of SELEX development processes, DNA and RNA aptamers reported for diseases and pathogenic agents as well have also been described in detail. But the emphasis of this review is on the development of aptamers which can block the function of virulent mycobacterial components for developing newer TB vaccine candidates and/or drug targets. Aptamers designed to target M.tb cell wall proteins, virulent factors, secretory proteins, or combination could orchestrate advanced diagnosis and therapeutic measures for tuberculosis.
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Affiliation(s)
- Shruti Srivastava
- Laboratory of Molecular Cell Biology, Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, India
| | - Philip Raj Abraham
- Unit of OMICS, ICMR-Vector Control Research Centre (VCRC), Puducherry, India
| | - Sangita Mukhopadhyay
- Laboratory of Molecular Cell Biology, Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, India
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Arif S, Akhter M, Khaliq A, Nisa ZU, Khan IH, Akhtar MW. Serodiagnostic evaluation of fusion proteins from multiple antigens of Mycobacterium tuberculosis for active TB. Tuberculosis (Edinb) 2021; 127:102053. [PMID: 33561630 DOI: 10.1016/j.tube.2021.102053] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/07/2021] [Accepted: 01/18/2021] [Indexed: 10/22/2022]
Abstract
Tuberculosis (TB) is a global health problem, being prevalent in the developing countries. A rapid, reliable and cost effective diagnostic method would help in controlling TB in the endemic populations. Development of suitable fusion molecules detecting multiple antibodies produced against Mycobacterium tuberculosis antigens would enhance sensitivity of serodiagnostic assays. In this study, EspC, CFP7 and PPE57 antigens of M. tuberculosis were selected for constructing fusion molecules after prediction of B-cell epitopes using in silico tools. Fusion proteins EspC-CFP7, HspX-EspC-CFP7 and HspX-EspC-CFP7-PPE57 were expressed in E.coli (BL21). The serodiagnostic potential of the individual antigens and their fusions was analyzed by screening 230 plasma samples of pulmonary TB patients. The single antigens HspX, EspC, CFP7, PPE57 showed sensitivities of 30%, 31%, 22% and 35%, respectively. The fusion protein EspC-CFP7 showed sensitivity of 43%. Linking of HspX antigen to the N-terminus of EspC-CFP7 fusion molecule increased sensitivity to 58%, while joining PPE57 antigen to the C-terminus of HspX-EspC-CFP7 increased sensitivity to 69%. The fusion protein HspX-EspC-CFP7-PPE57 seems to be a promising molecule for use in the development of fusions with higher sensitivity.
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Affiliation(s)
- Shaista Arif
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan
| | - Mohsina Akhter
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan
| | - Aasia Khaliq
- Armed Forces Institute of Pathology, Rawalpindi, Pakistan
| | | | - Imran H Khan
- Department of Pathology and Laboratory Medicine, University of California, Davis, USA
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Song N, Li Z, Cui Z, Chen L, Cui Y, Dang G, Li Z, Li H, Liu S. The prominent alteration in transcriptome and metabolome of Mycobacterium bovis BCG str. Tokyo 172 induced by vitamin B 1. BMC Microbiol 2019; 19:104. [PMID: 31117936 PMCID: PMC6530141 DOI: 10.1186/s12866-019-1492-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 05/14/2019] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Vitamin B1 (VB1) is a crucial dietary nutrient and essential cofactor for several key enzymes in the regulation of cellular and metabolic processes, and more importantly in the activation of immune system. To date, the precise role of VB1 in Mycobacterium tuberculosis remains to be fully understood. RESULTS In this study, the transcriptional and metabolic profiles of VB1-treated Mycobacterium. bovis BCG were analyzed by RNA-sequencing and LC-MS (Liquid chromatography coupled to mass spectrometry). The selection of BCG strain was based on its common physiological features shared with M. tuberculosis. The results of cell growth assays demonstrated that VB1 inhibited the BCG growth rate in vitro. Transcriptomic analysis revealed that the expression levels of genes related to fatty acid metabolism, cholesterol metabolism, glycolipid catabolism, DNA replication, protein translation, cell division and cell wall formation were significantly downregulated in M. bovis BCG treated with VB1. In addition, the metabolomics LC-MS data indicated that most of the amino acids and adenosine diphosphate (ADP) were decreased in M. bovis BCG strain after VB1 treatment. CONCLUSIONS This study provides the molecular and metabolic bases to understand the impacts of VB1 on M.bovis BCG.
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Affiliation(s)
- Ningning Song
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Zhaoli Li
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Ziyin Cui
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Liping Chen
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Yingying Cui
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Guanghui Dang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Zhe Li
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - He Li
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Siguo Liu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
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Ren N, JinLi J, Chen Y, Zhou X, Wang J, Ge P, Khan FA, Zhang L, Hu C, Robertson ID, Chen H, Guo A. Identification of new diagnostic biomarkers for Mycobacterium tuberculosis and the potential application in the serodiagnosis of human tuberculosis. Microb Biotechnol 2018; 11:893-904. [PMID: 29952084 PMCID: PMC6116745 DOI: 10.1111/1751-7915.13291] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 05/03/2018] [Accepted: 05/22/2018] [Indexed: 12/13/2022] Open
Abstract
Mycobacterium tuberculosis (M. tuberculosis) regions of difference (RD) encode proteins which are potentially useful as diagnostic reagents for tuberculosis (TB). In this study, 75 genes from M. tuberculosis RD1‐RD16 were successfully cloned from which 68 proteins were expressed and purified. Three serum pools from patients with pulmonary TB (PTB), extra‐pulmonary tuberculosis (EPTB) and healthy controls (HC) were used to preliminarily screen individual RD proteins. The OD630 ratio of the PTB or EPTB to the HC group ≥ 2‐fold was positive. As a result, 29 proteins were obtained. The serological response to the identified antigens was further verified using 58 PTB samples with 38 sera from smear‐positive PTB (PTB‐SP) patients and 20 sera from smear‐negative PTB (PTB‐SN) patients, 16 EPTB samples, 42 latent M. tuberculosis infection samples and 40 HCs by indirect ELISA. With respect to the PTB diagnosis, receiver operating characteristic analysis showed that Rv0222 [area under the curve (AUC), 0.8129; 95% confidence interval (CI), 0.7280–0.8979] and Rv3403c (AUC, 0.8537; 95% CI, 0.7779–0.9294) performed better than ESAT6/CFP10 (AUC, 0.7435; 95% CI, 0.6465–0.8406). Rv0222 and Rv3403c demonstrated the highest diagnostic ability in the PTB‐SP group (sensitivity, 86.8%; specificity, 80%), while Rv3403c demonstrated the highest diagnostic ability in the PTB‐SN group (sensitivity, 70%; specificity, 80%). With respect to the EPTB diagnosis, Rv0222 exhibited the highest diagnostic value (AUC, 0.7523; sensitivity, 68.8%; specificity, 87.5%). In addition, the combination of Rv0222 and Rv3403c improved the test for PTB‐SN. These results indicate that Rv0222 and Rv3403c would be potential diagnostic biomarkers for active TB serodiagnosis. Mouse experiments demonstrated that Rv0222 and Rv3403c elicited specific cellular and humoral responses which were characterized by production of IFN‐γ, IgG1, and IgG2a, but a higher level of IgG1 than IgG2a.
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Affiliation(s)
- Ningning Ren
- The State Key Laboratory of Agricultural Microbiology, Wuhan, 430070, China.,College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China
| | - Jingfang JinLi
- The State Key Laboratory of Agricultural Microbiology, Wuhan, 430070, China.,College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yingyu Chen
- The State Key Laboratory of Agricultural Microbiology, Wuhan, 430070, China.,College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China
| | - Xia Zhou
- Tuberculosis Department, Wuhan Medical Treatment Center, Wuhan, 430023, China
| | - Jieru Wang
- The State Key Laboratory of Agricultural Microbiology, Wuhan, 430070, China.,College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China
| | - Pan Ge
- The State Key Laboratory of Agricultural Microbiology, Wuhan, 430070, China.,College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China
| | - Farhan Anwar Khan
- Department of Animal Health, Faculty of Animal Husbandry and Veterinary Sciences, The University of Agriculture, Peshawar, Khyber Pakhtunkhwa, 25120, Pakistan
| | - Li Zhang
- Tuberculosis Department, Wuhan Medical Treatment Center, Wuhan, 430023, China
| | - Changmin Hu
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China
| | - Ian D Robertson
- The State Key Laboratory of Agricultural Microbiology, Wuhan, 430070, China.,College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.,Hubei International Scientific and Technological Cooperation Base of Veterinary Epidemiology, Huazhong Agricultural University, Wuhan, 430070, China.,College of Veterinary Medicine, Murdoch University, Murdoch, WA, 6160, Australia
| | - Huanchun Chen
- The State Key Laboratory of Agricultural Microbiology, Wuhan, 430070, China.,College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.,Hubei International Scientific and Technological Cooperation Base of Veterinary Epidemiology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Aizhen Guo
- The State Key Laboratory of Agricultural Microbiology, Wuhan, 430070, China.,College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.,Hubei International Scientific and Technological Cooperation Base of Veterinary Epidemiology, Huazhong Agricultural University, Wuhan, 430070, China
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12
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Luo L, Zhu L, Yue J, Liu J, Liu G, Zhang X, Wang H, Xu Y. Antigens Rv0310c and Rv1255c are promising novel biomarkers for the diagnosis of Mycobacterium tuberculosis infection. Emerg Microbes Infect 2017; 6:e64. [PMID: 28698665 PMCID: PMC5567170 DOI: 10.1038/emi.2017.54] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 05/21/2017] [Accepted: 05/22/2017] [Indexed: 12/19/2022]
Abstract
This study aimed to identify novel immunogenic epitopes from Mycobacterium tuberculosis (MTB) that could be used in tuberculosis (TB) diagnostics. To determine the diagnostic potential of mycobacterial antigens in serodiagnosis of TB, 256 patients were enrolled in a study and divided into two groups: 126 smear-positive pulmonary TB patients (SPPT) and 130 smear-negative pulmonary TB patients (SNPT); 152 bacillus Calmette-Guerin (BCG)-vaccinated healthy people were used as a control. Murine results showed that antigens Rv0310c-E from RD 8 and Rv1255c-E from RD 10 were strongly immunogenic to Th1 cells and induced a great humoral response. Receiver operating characteristic analysis indicated that Rv0310c-E (area under the curve (AUC): 0.800) and Rv1255c-E (AUC: 0.808) performed better than ESAT-6 (AUC: 0.665) and CFP-10 (AUC: 0.623) proteins but were comparable with Rv3425 (AUC: 0.788) protein in a human serum IgG analysis. Rv0310c-E demonstrated the highest diagnostic ability for the SPPT group (Youden index: 0.5602, sensitivity: 69.84%, specificity: 86.18%), while Rv1255c-E demonstrated the highest diagnostic ability for the SNPT group (Youden index: 0.5674, sensitivity: 73.84%, specificity: 82.89%). In addition, combination analysis found that antigen Rv0310c-E, coupled with the Rv3425 protein (Youden index: 0.6098, sensitivity: 87.30%, specificity: 73.68%) had the strongest performance for TB diagnostics of the SPPT group, and the single antigen Rv1255c-E was strongest for the SNPT group. These results suggest that antigens Rv0310c-E and Rv1255c-E are potential antigens for TB serodiagnostic tests, which may facilitate detection of MTB in smear-negative and smear-positive patients.
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Affiliation(s)
- Liulin Luo
- State Key Laboratory of Genetic Engineering, Institute of Genetics, Fudan University, Shanghai 200433, China.,Department of Clinical Laboratory Medicine, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200433, China
| | - Lin Zhu
- State Key Laboratory of Genetic Engineering, Institute of Genetics, Fudan University, Shanghai 200433, China
| | - Jun Yue
- Department of Clinical Laboratory Medicine, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200433, China
| | - Jianping Liu
- State Key Laboratory of Genetic Engineering, Institute of Genetics, Fudan University, Shanghai 200433, China
| | - Guoyuan Liu
- State Key Laboratory of Genetic Engineering, Institute of Genetics, Fudan University, Shanghai 200433, China
| | - Xuelian Zhang
- State Key Laboratory of Genetic Engineering, Institute of Genetics, Fudan University, Shanghai 200433, China
| | - Honghai Wang
- State Key Laboratory of Genetic Engineering, Institute of Genetics, Fudan University, Shanghai 200433, China
| | - Ying Xu
- State Key Laboratory of Genetic Engineering, Institute of Genetics, Fudan University, Shanghai 200433, China
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13
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Abraham PR, Pathak N, Pradhan G, Sumanlatha G, Mukhopadhyay S. The N-terminal domain of Mycobacterium tuberculosis PPE17 (Rv1168c) protein plays a dominant role in inducing antibody responses in active TB patients. PLoS One 2017. [PMID: 28651002 PMCID: PMC5484515 DOI: 10.1371/journal.pone.0179965] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The PPE (proline-proline-glutamic acid) proteins of Mycobacterium tuberculosis are characterized by a conserved N-terminal domain of approximately 180 amino acids and variable C-terminal domain. Since last decade, these proteins have gained much importance in the serodiagnosis of tuberculosis (TB) as they act as a source of antigenic variation. We have demonstrated earlier that one of the PPE proteins PPE17 (Rv1168c) induces strong B-cell and T-cell responses in active TB disease and also displays a higher antibody titer compared to immunodominant antigens such as ESAT-6, Hsp60 and PPD. However, the immunodominant domain of PPE17 (N-terminal or C-terminal) was not examined in detail. In the present study, we observed that antibody responses elicited in TB patients were directed mostly towards the N-terminal domain of PPE17 (N-PPE17). The antibody generated against N-PPE17 in TB patients did not significantly cross-react with N-terminal domains of other PPE proteins used in this study. Our data suggest that the N-terminal domain of PPE17 protein is immunodominant and could be used as a better serodiagnostic marker than the full-length PPE17 protein.
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Affiliation(s)
- Philip Raj Abraham
- Laboratory of Molecular Cell Biology, Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, India
| | - Niteen Pathak
- Laboratory of Molecular Cell Biology, Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, India
| | - Gourango Pradhan
- Laboratory of Molecular Cell Biology, Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, India
- Graduate Studies, Manipal University, Manipal, India
| | | | - Sangita Mukhopadhyay
- Laboratory of Molecular Cell Biology, Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, India
- * E-mail: ,
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Delogu G, Brennan MJ, Manganelli R. PE and PPE Genes: A Tale of Conservation and Diversity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1019:191-207. [PMID: 29116636 DOI: 10.1007/978-3-319-64371-7_10] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
PE and PPE are two large families of proteins typical of mycobacteria whose structural genes in the Mycobacterium tuberculosis complex (MTBC) occupy about 7% of the total genome. The most ancestral PE and PPE proteins are expressed by genes that belong to the same operon and in most cases are found inserted in the esx clusters, encoding a type VII secretion system. Duplication and expansion of pe and ppe genes, coupled with intragenomic and intergenomic recombination events, led to the emergence of the polymorphic pe_pgrs and ppe_mptr genes in the MTBC genome. The role and function of these proteins, and particularly of the polymorphic subfamilies, remains elusive, although it is widely accepted that PE and PPE proteins may represent a specialized collection used by MTBC to interact with the complex host immune system of mammals. In this chapter, we summarize what has been discovered since the identification of these genes in 1998, focusing on M. tuberculosis genetic variability, host-pathogen interaction and TB pathogenesis.
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Affiliation(s)
- Giovanni Delogu
- Institute of Microbiology, Università Cattolica del Sacro Cuore, Largo A. Gemelli, 8, 00168, Rome, Italy.
| | | | - Riccardo Manganelli
- Department of Molecular Medicine, University of Padua, Via A. Gabelli, 63, 35121, Padua, Italy
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15
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The Mycobacterium tuberculosis PPE protein Rv1168c induces stronger B cell response than Rv0256c in active TB patients. INFECTION GENETICS AND EVOLUTION 2015; 40:339-345. [PMID: 26364913 DOI: 10.1016/j.meegid.2015.09.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 07/30/2015] [Accepted: 09/08/2015] [Indexed: 10/23/2022]
Abstract
Tuberculosis (TB) caused by Mycobacterium tuberculosis is a serious global health problem and is responsible for millions of deaths every year. For effective control of this dreadful disease, it is necessary to diagnose TB cases at the initial stages of infection. The serodiagnosis of disease represents simple, rapid and inexpensive method that can be used at the primary health care levels. In this study we have compared sensitivity of two PPE proteins of M. tuberculosis, i.e., Rv0256c and Rv1168c for their use as serodiagnostic markers in active tuberculosis patients. Employing a standardized enzyme immunoassay with these PPE proteins as candidate antigens we were able to successfully discriminate the TB patients' sera from the BCG-vaccinated healthy controls. Further, we observed that Rv1168c displayed higher sensitivity in detecting extrapulmonary and smear negative pulmonary TB cases which are difficult to diagnose by available diagnostic methods. Overall the study highlights that Rv1168c can be used as a potential serodiagnostic marker for the diagnosis of active tuberculosis disease.
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16
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Yang E, Wang F, Xu Y, Wang H, Hu Y, Shen H, Chen ZW. A lentiviral vector-based therapeutic vaccine encoding Ag85B-Rv3425 potently increases resistance to acute tuberculosis infection in mice. Acta Biochim Biophys Sin (Shanghai) 2015; 47:588-96. [PMID: 26112017 DOI: 10.1093/abbs/gmv059] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2015] [Accepted: 04/16/2015] [Indexed: 11/13/2022] Open
Abstract
Few treatment options for multidrug-resistant tuberculosis (TB) and extensively drug-resistant TB call attention to the development of novel therapeutic approaches for TB. Therapeutic vaccines are promising candidates because they can induce antigen-specific cellular immune responses, which play an important role in the elimination of Mycobacterium tuberculosis (MTB). In this study, a novel lentiviral vector therapeutic vaccine for delivering MTB-specific fusion protein Ag85B-Rv3425 was constructed. Results showed that one single-injection of this recombinant lentivirus vaccine could trigger antigen-specific Th1-type immune responses in mice. More importantly, mice with acute infection benefited a lot from a single-dose administration of this vaccine by markedly reduced MTB burdens in lungs and spleens as well as attenuated lesions in lungs compared with untreated mice. These results displayed good prospects of this novel vaccine for the immunotherapy of TB.
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Affiliation(s)
- Enzhuo Yang
- Unit of Anti-Tuberculosis Immunity, Key Laboratory of Molecular Virology and Immunology, Institute Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200031, China
| | - Feifei Wang
- Department of Medical Microbiology and Parasitology, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Ying Xu
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Honghai Wang
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Yong Hu
- Department of Neonatology, Shanghai Children's Hospital, Shanghai Jiao Tong University, Shanghai 200040, China
| | - Hongbo Shen
- Unit of Anti-Tuberculosis Immunity, Key Laboratory of Molecular Virology and Immunology, Institute Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200031, China
| | - Zheng W Chen
- Unit of Anti-Tuberculosis Immunity, Key Laboratory of Molecular Virology and Immunology, Institute Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200031, China
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17
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Xu Y, Yang E, Huang Q, Ni W, Kong C, Liu G, Li G, Su H, Wang H. PPE57 induces activation of macrophages and drives Th1-type immune responses through TLR2. J Mol Med (Berl) 2015; 93:645-62. [PMID: 25586105 DOI: 10.1007/s00109-014-1243-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Revised: 12/04/2014] [Accepted: 12/14/2014] [Indexed: 01/10/2023]
Abstract
UNLABELLED Proline-glutamic acid (PE) and proline-proline-glutamic acid (PPE) are related proteins exclusive to Mycobacteria that play diverse roles in modulating critical innate immune pathways. In this study, we observed that the PPE57 protein is associated with the cell wall and is exposed on the cell surface. PPE57 enhances Mycobacterium spp. entering into macrophages and plays a role in macrophage phagocytosis. To explore the underlying mechanism, we demonstrated that PPE57 is able to recognise Toll-like receptor 2 (TLR2) and further induce macrophage activation by augmenting the expression of several cell surface molecules (CD40, CD80, CD86 and MHC class II) and pro-inflammatory cytokines (TNF-α, IL-6 and IL-12p40) within macrophages. These molecules are involved in the mitogen-activated protein kinase (MAPK) and nuclear factor κB (NF-κB) signalling pathways. We demonstrated that PPE57 effectively polarises T cells to secrete interferon (IFN)-γ and IL-2 and to up-regulate CXCR3 expression in vivo and in vitro, suggesting that this protein may contribute to Th1 polarisation during the immune response. Moreover, recombinant Bacillus Calmette-Guérin (BCG) over-expressing PPE57 could provide better protective efficacy against Mycobacterium tuberculosis challenge compared with BCG. Taken together, our data provides several pieces of evidence that PPE57 may regulate innate and adaptive immunity by interacting with TLR2. These findings indicate that PPE57 protein is a potential antigen for the rational design of an efficient vaccine against M. tuberculosis. KEY MESSAGES PPE57 is located on the cell surface and enhances mycobacterium entry into macrophage. PPE57 interacts directly with TLR2 on macrophages. PPE57 plays a key role in the activation of macrophages in a TLR2-dependent manner. PPE57 induces a Th1 immune response via TLR2-mediated macrophage functions. Recombinant BCG over-expressing PPE57 could improve protective efficacy against M. tuberculosis.
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Affiliation(s)
- Ying Xu
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Science, Fudan University, No. 220 Handan Road, Shanghai, 200433, China,
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18
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Zhao J, Sun Z, Pei H, Ye J, Chen C, Samten B, Zhang S, Guo X. Immunological evaluation of a novel Mycobacterium tuberculosis antigen, Rv3117, absent in Mycobacterium bovis BCG. Mol Med Rep 2013; 8:1587-93. [PMID: 24045507 DOI: 10.3892/mmr.2013.1687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2013] [Accepted: 09/04/2013] [Indexed: 11/05/2022] Open
Abstract
Tuberculosis (TB) remains a global infectious disease. To investigate the value of a novel Mycobacterium tuberculosis (M. tuberculosis) region of difference 5 (RD5)-encoded antigen, Rv3117, in the development of effective immuno-diagnostics and vaccines against TB, the immune responses to the antigen were examined in human subjects, as well as in C57BL/6 mice. The results showed that Rv3117 was able to evoke specific humoral and cellular immune responses. Consistent with the results from the RD1-encoded antigens, culture filtrate protein 10 kDa (CFP-10) and early secreted antigenic target 6 kDa (ESAT-6), the immunoglobulin G (IgG), IgM and IgA antibody responses to Rv3117 were able to statistically distinguish between the 65 patients with active pulmonary TB and the 59 healthy controls (P<0.01, respectively). In addition, higher levels of Rv3117‑specific interferon-γ (IFN-γ) were observed in immunized C57BL/6 mice than in the negative control mice (P<0.05). Furthermore, high titers of total IgG, IgG1 and IgG2a antibodies were present in the sera from immunized mice, even six weeks subsequent to the immunization. In conclusion, the present results suggested that Rv3117 may be used as a candidate for the development of TB immunodiagnostics and vaccine design.
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Affiliation(s)
- Junwei Zhao
- Department of Medical Microbiology and Parasitology, School of Medicine, Shanghai Jiao Tong University, Shanghai 200025, P.R. China
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19
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Mycobacterium tuberculosis PPE protein Rv0256c induces strong B cell response in tuberculosis patients. INFECTION GENETICS AND EVOLUTION 2013; 22:244-9. [PMID: 23827809 DOI: 10.1016/j.meegid.2013.06.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 06/19/2013] [Accepted: 06/23/2013] [Indexed: 11/20/2022]
Abstract
Tuberculosis (TB) is one of the most important diseases of humans and major public health problem worldwide. Early and accurate diagnosis of TB is necessary for the treatment, prevention, and control of TB. Therefore, it is important to identify suitable antigens that can differentiate active tuberculosis patients from BCG-vaccinated individuals. In the present study, we have used Rv0256c (PPE2) protein of Mycobacterium tuberculosis to screen the sera of infected patients belonging to different clinical TB presentations, and BCG-vaccinated clinically healthy individuals by enzyme immunoassay. Our results demonstrated that Rv0256c displayed stronger and specific immunoreactivity against the sera obtained from clinically active tuberculosis patients compared to PPD and ESAT-6 and could differentiate the TB-patients from the BCG-vaccinated controls. Importantly, Rv0256c was also found to detect even the extrapulmonary and smear-negative pulmonary cases which often are tedious and difficult to detect using conventional diagnostic methods. This study suggests that Rv0256c can be used as a potential marker for the serodiagnosis of tuberculosis patients.
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20
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Mustafa AS. In silico analysis and experimental validation of Mycobacterium tuberculosis -specific proteins and peptides of Mycobacterium tuberculosis for immunological diagnosis and vaccine development. Med Princ Pract 2013; 22 Suppl 1:43-51. [PMID: 24008694 PMCID: PMC5586813 DOI: 10.1159/000354206] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 07/08/2013] [Indexed: 01/15/2023] Open
Abstract
Comparative analyses of the Mycobacterium tuberculosis genome with the genomes of other mycobacteria have led to the identification of several genomic regions of difference (RDs) between M. tuberculosis and M. bovis BCG. The identification of immunodominant and HLA-promiscuous antigens and peptides encoded by these RDs could be useful for diagnosis and the development of new vaccines against tuberculosis. The analysis of RD proteins and peptides by in silico methods (using computational programs to predict major and HLA-promiscuous antigenic proteins and peptides) and experimental validations (using peripheral blood mononuclear cells and sera from tuberculosis patients and BCG-vaccinated healthy subjects to assess antigen-specific cellular and humoral immune responses in vitro) identified several major antigens and peptides. To evaluate the in vivo potentials, the genes of immunodominant antigens were cloned and expressed in DNA vaccine vectors. Immunizations of experimental animals with the recombinant constructs induced antigen-specific cellular responses. Further experiments showed that each of these proteins had several T and B cell epitopes scattered throughout their sequence, which confirmed their strong immunogenicity. In conclusion, the bioinformatics-based in silico identification of promiscuous antigens and peptides of M. tuberculosis is a useful approach to identify new candidates important for diagnosis and vaccine applications.
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Affiliation(s)
- Abu Salim Mustafa
- *Abu Salim Mustafa, Department of Microbiology, Faculty of Medicine, Kuwait University, PO Box 24923, Safat 13110 (Kuwait), E-Mail
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21
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Chen F, Zhai MX, Zhu YH, Qi YM, Zhai WJ, Gao YF. In vitro and in vivo identification of a novel cytotoxic T lymphocyte epitope from Rv3425 of Mycobacterium tuberculosis. Microbiol Immunol 2012; 56:548-53. [PMID: 22537173 PMCID: PMC7168511 DOI: 10.1111/j.1348-0421.2012.00470.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The identification of novel cytotoxic T lymphocyte (CTL) epitopes is important to analysis of the involvement of CD8+ T cells in Mycobacterium tuberculosis infection as well as to the development of peptide vaccines. In this study, a novel CTL epitope from region of difference 11 encoded antigen Rv3425 was identified. Epitopes were predicted by the reversal immunology approach. Rv3425‐p118 (LIASNVAGV) was identified as having relatively strong binding affinity and stability towards the HLA‐A*0201 molecule. Peripheral blood mononuclear cells pulsed by this peptide were able to release interferon‐γ in healthy donors (HLA‐A*02+ purified protein derivative+). In cytotoxicity assays in vitro and in vivo, Rv3425‐p118 induced CTLs to specifically lyse the target cells. Therefore, this epitope could provide a subunit component for designing vaccines against Mycobacterium tuberculosis.
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Affiliation(s)
- Fei Chen
- Department of Bioengineering, Zhengzhou University, Zhengzhou 450001, China
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22
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Mycobacterium tuberculosis region of difference (RD) 2 antigen Rv1985c and RD11 antigen Rv3425 have the promising potential to distinguish patients with active tuberculosis from M. bovis BCG-vaccinated individuals. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2012; 20:69-76. [PMID: 23136116 DOI: 10.1128/cvi.00481-12] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Antigens encoded in the region of difference (RD) of Mycobacterium tuberculosis constitute a potential source of specific immunodiagnostic antigens for distinguishing tuberculosis (TB) infection from BCG vaccination. We evaluated the diagnostic potential of specific T-cell epitopes selected from two immunodominant antigens, Rv1985c and Rv3425, from RD2 and RD11, respectively, on the basis of epitope mapping, in TB patients and BCG-vaccinated healthy individuals. Using a whole-blood gamma interferon release assay, a wide array of epitopes was recognized on both Rv1985c and Rv3425 in TB patients. Those epitopes that could specifically discriminate TB infection from BCG vaccination were carefully selected, and the most promising peptide pools from Rv1985c showed a sensitivity of 53.9% and a specificity of 95.5%. When the novel specific peptides from Rv1985c joined the diagnostic antigens in the QuantiFERON-TB Gold In-Tube (QFT-IT) assay, the sensitivity was increased from 86.4% to 96.2%, with no drop in specificity. These results indicate that the peptide pools selected from Rv1985c and Rv3425 have the potential to diagnose TB infection by a method that may be routinely used in clinical laboratories.
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23
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Deng W, Xie J. Ins and outs of Mycobacterium tuberculosis PPE family in pathogenesis and implications for novel measures against tuberculosis. J Cell Biochem 2012; 113:1087-95. [PMID: 22275049 DOI: 10.1002/jcb.23449] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Mycobacterium tuberculosis is the most successful pathogen with multiple mechanisms to subvert host immune response, resulting in insidious disease. A unique Mycobacterium antigen family termed PPE (Pro-Pro-Glu) has long been widely speculated as "molecular mantra" to escape host immunity. Members of this family are characterized by a conserved N terminal and a variable C terminal. This family associated closely with ESAT-6(ESX) secretion system and largely located in cell wall or cell membrane. The expression of PPE protein is temporally regulated, and highly expressed during M. tuberculosis persistence. Importantly, the distribution of PPE family is so far limited to Mycobacterium genus, prevalent among pathogenic Mycobacterium species. It is tempting to explore this family due to its potential in the latency and reactivation of M. tuberculosis. The evolution, structure, and functions of most PPE proteins remain elusive. The understanding of these questions will deepen our appreciation of the pathogenesis of M. tuberculosis and accelerate novel anti-TB measures discovery.
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Affiliation(s)
- Wanyan Deng
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, School of Life Sciences, Southwest University, Beibei, Chongqing 400715, China
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Opportunities for improved serodiagnosis of human tuberculosis, bovine tuberculosis, and paratuberculosis. Vet Med Int 2012; 2012:674238. [PMID: 22720192 PMCID: PMC3375143 DOI: 10.1155/2012/674238] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2012] [Accepted: 04/02/2012] [Indexed: 11/21/2022] Open
Abstract
Mycobacterial infections—tuberculosis (TB), bovine tuberculosis (bTB), and Johne's disease (JD)—are major infectious diseases of both human and animals. Methods presently in use for diagnosis of mycobacterial infections include bacterial culture, nucleic acid amplification, tuberculin skin test, interferon-γ assay, and serology. Serological tests have several advantages over other methods, including short turn-around time, relatively simple procedures, and low cost. However, current serodiagnostic methods for TB, bTB and JD exhibit low sensitivity and/or specificity. Recent studies that have aimed to develop improved serodiagnostic tests have mostly focused on identifying useful species-specific protein antigens. A review of recent attempts to improve diagnostic test performance indicates that the use of multiple antigens can improve the accuracy of serodiagnosis of these mycobacterial diseases. Mycobacteria also produce a variety of species-specific nonprotein molecules; however, only a few such molecules (e.g., cord factor and lipoarabinomannan) have so far been evaluated for their effectiveness as diagnostic antigens. For TB and bTB, there has been recent progress in developing laboratory-free diagnostic methods. New technologies such as microfluidics and “Lab-on-Chip” are examples of promising new technologies that can underpin development of laboratory-free diagnostic devices for these mycobacterial infections.
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Identification of RD5-encoded Mycobacterium tuberculosis proteins as B-cell antigens used for serodiagnosis of tuberculosis. Clin Dev Immunol 2012; 2012:738043. [PMID: 22701501 PMCID: PMC3373134 DOI: 10.1155/2012/738043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2011] [Accepted: 04/01/2012] [Indexed: 12/02/2022]
Abstract
Comparative genomic studies have identified several Mycobacterium tuberculosis-specific genomic regions of difference (RDs) which are absent in the vaccine strains of Mycobacterium bovis BCG and which may be useful in the specific diagnosis of tuberculosis (TB). In this study, all encoded proteins from DNA segment RD5 of Mycobacterium tuberculosis, that is, Rv3117–Rv3121, were recombined and evaluated by enzyme-linked immunosorbent assays for antibody reactivity with sera from HIV-negative pulmonary TB patients (n = 60) and healthy controls (n = 32). The results identified two immunodominant antigens, that is, Rv3117 and Rv3120, both of which revealed a statistically significant antigenic distinction between healthy controls and TB patients (P < 0.05). In comparison with the well-known early-secreted antigen target 6 kDa (ESAT-6) (sensitivity 21.7%, specificity 90.6%), the higher detection sensitivity and higher specificity were achieved (Rv3117: sensitivity 25%, specificity 96.9%; Rv3120: sensitivity 31.7%, specificity 96.9%). Thus, the results highlight the immunosensitive and immunospecific nature of Rv3117 and Rv3120 and indicate promise for their use in the serodiagnosis of TB.
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Cheng Z, Zhao JW, Sun ZQ, Song YZ, Sun QW, Zhang XY, Zhang XL, Wang HH, Guo XK, Liu YF, Zhang SL. Evaluation of a novel fusion protein antigen for rapid serodiagnosis of tuberculosis. J Clin Lab Anal 2012; 25:344-9. [PMID: 21919069 DOI: 10.1002/jcla.20483] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The detection of Mycobacterium tuberculosis-specific antibodies in human sera has been a rapid and important diagnostic aid for tuberculosis (TB) control and prevention. However, any single antigen is not enough to be used to cover the antibody profiles of all TB patients. In this study, a novel fusion protein was constructed using gene splicing by overlap extension (SOEing), and then the antibody level against it in 171 TB patients and 86 controls was evaluated by enzyme-linked immunosorbent assay. Compared with the three individual antigen (16 kDa: sensitivity 19.9%, specificity 96.5%; MPT64: sensitivity 75.4%, specificity 34.9%; 38 kDa: sensitivity 33.3%, specificity 83.7%), the fusion protein antigen (sensitivity 42.1%, specificity 89.5%) gave the best diagnostic performance with the largest receiver operating characteristic curve area 0.656 (95% confidence interval [CI], 0.590-0.721; P<0.01). These results suggested that the novel fusion protein antigen successfully constructed by gene SOEing provided the improved diagnostic performance for TB, and other mycobacterial multiepitope fusion proteins may also be worthy of investigation for further enhancing the detection sensitivity.
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Affiliation(s)
- Zhe Cheng
- The First Affiliated Hospital of Zhengzhou University, Institute of Clinical Medical Research of Henan Universities, Zhengzhou, PR China
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Liu S, Han W, Sun C, Lei L, Feng X, Yan S, Diao Y, Gao Y, Zhao H, Liu Q, Yao C, Li M. Subtractive screening with the Mycobacterium tuberculosis surface protein phage display library. Tuberculosis (Edinb) 2011; 91:579-86. [PMID: 21900047 DOI: 10.1016/j.tube.2011.07.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2011] [Revised: 07/22/2011] [Accepted: 07/25/2011] [Indexed: 11/20/2022]
Abstract
Surface proteins consist of secreted and membrane proteins and play a central role in the interaction of the pathogen with its environment, especially in the pathogenicity of Mycobacterium tuberculosis (MTB). Research on surface proteins in MTB has focused on 2D electrophoresis of culture filtrate proteins (CFP), extraction of transmembrane proteins with detergent and predicting their properties with a range of available algorithms. However, functional analysis of these secretomes is possible only if many proteins are expressed and purified individually, which limits a large number of studies to the function of the proteome. Here, we utilized a phage display system to construct a whole genomic surface protein phage display library of MTB, which can complete direct selection, identification, expression, purification and functional research of surface proteins of MTB. With this system we made a new serological approach involving iterative subtraction screening. Cross-reactivity of antibodies was reduced by preadsorption of the surface protein phage display library with the sera of healthy BCG-vaccinated individuals prior to studying their reactivity against the sera of tuberculosis (TB) patients. As a result six antigens were identified, three of which have not previously been reported as diagnosis antigens. The surface protein phage display library shows great promise in the study of MTB.
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Affiliation(s)
- Shanshan Liu
- College of Animal Science and Veterinary Medicine, Jilin University, Xi'an Road 5333#, Changchun 130062, China
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Zhu YH, Gao YF, Chen F, Liu W, Zhai MX, Zhai WJ, Qi YM, Ye Y. Identification of novel T cell epitopes from efflux pumps of Mycobacterium tuberculosis. Immunol Lett 2011; 140:68-73. [PMID: 21756938 DOI: 10.1016/j.imlet.2011.06.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 06/26/2011] [Accepted: 06/27/2011] [Indexed: 10/18/2022]
Abstract
Cytotoxic T lymphocytes (CTLs) play an important role in the immunity of Mycobacterium tuberculosis (Mtb) infection. In the present study, the identification of novel CTL epitopes from efflux pumps, Rv1258c and Rv1410c, was reported. Candidate native peptides and their analogues were predicted with prediction programs. Rv1410c-p510 (TLAPQVEPL) and Rv1410c-p510-1Y9V (YLAPQVEPV) showed potent binding affinity and stability towards HLA-A*0201 molecule. In enzyme-linked immunospot (ELISPOT) assay, the CTLs induced from peripheral blood mononuclear cells (PBMCs) by these peptides could release interferon-γ (IFN-γ) in at least one healthy donor (HLA-A*02(+), PPD(+)). In cytotoxicity assay in vitro and in vivo, the CTLs induced by Rv1410c-p510-1Y9V could specifically lyse peptide-loaded T2 cells. This is the first report to identify CTL epitopes from the efflux pumps of Mtb. The novel epitope identified could serve as candidate to the multivalent peptide vaccine against drug-resistant M. tuberculosis.
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Affiliation(s)
- Yu-Huang Zhu
- Department of Bioengineering, Zhengzhou University, 100 Science Road, Zhengzhou 450001, China
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Assessment of five antigens from Mycobacterium tuberculosis for serodiagnosis of tuberculosis. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2011; 18:565-70. [PMID: 21288992 DOI: 10.1128/cvi.00507-10] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Tuberculosis (TB), caused by Mycobacterium tuberculosis, is a major public health issue, particularly in developing countries, and thus effective diagnostic methods for TB remain a central theme in basic and clinical research. To evaluate five antigens (38-kDa protein [38kDa], Rv3621c, Rv3618, 38kDa-ESAT-6 [38E6], and Ag85B-HBHA [AH]) in serological tests for TB patients, we recruited 288 patients and 201 healthy controls. The median IgG reactivity to 38kDa, 38E6, and AH was higher than that to Rv3618 and Rv3621c in pulmonary TB. 38kDa and 38E6 provided high sensitivities in pulmonary TB but low sensitivities in extrapulmonary TB (EPTB). The specificities achieved by 38kDa and 38E6 ranged from 82.0% to 93.9% in patients with non-TB respiratory disease (PD) and in controls. 38kDa and 38E6 exhibited lower sensitivities and higher specificities than their combinations with Rv3618. These findings provide useful information on the relative importance of the above five antigens and suggest that combinations of Rv3618 with 38kDa and 38E6 can increase their sensitivities, but their specificities need to be further increased.
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Mycobacterial PE/PPE proteins at the host-pathogen interface. Clin Dev Immunol 2011; 2011:497203. [PMID: 21318182 PMCID: PMC3034920 DOI: 10.1155/2011/497203] [Citation(s) in RCA: 192] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Accepted: 12/23/2010] [Indexed: 11/17/2022]
Abstract
The mycobacterial PE/PPE proteins have attracted much interest since their formal identification just over a decade ago. It has been widely speculated that these proteins may play a role in evasion of host immune responses, possibly via antigenic variation. Although a cohesive understanding of their function(s) has yet to be established, emerging data increasingly supports a role for the PE/PPE proteins at multiple levels of the infectious process. This paper will delineate salient features of the families revealed by comparative genomics, bioinformatic analyses and genome-wide screening approaches and will summarise existing knowledge of subcellular localization, secretion pathways, and protein structure. These characteristics will be considered in light of findings on innate and adaptive host responses to PE/PPE proteins, and we will review the increasing body of data on B and T cell recognition of these proteins. Finally, we will consider how current knowledge and future explorations may contribute to a more comprehensive understanding of these intriguing proteins and their involvement in host pathogen interactions. Ultimately this information could underpin future intervention strategies, for example, in the area of new and improved diagnostic tools and vaccine candidates.
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Rv1985c, a promising novel antigen for diagnosis of tuberculosis infection from BCG-vaccinated controls. BMC Infect Dis 2010; 10:273. [PMID: 20849593 PMCID: PMC2949761 DOI: 10.1186/1471-2334-10-273] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2009] [Accepted: 09/17/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Antigens encoded in the region of difference (RD) of Mycobacterium tuberculosis constitute a potential source of specific antigens for immunodiagnosis. In the present study, recombinant protein Rv1985c from RD2 was cloned, expressed, purified, immunologically characterized and investigated for its potentially diagnostic value for tuberculosis (TB) infection among BCG-vaccinated individuals. METHODS T-cell response to Rv1985c was evaluated by IFN-γ ELISPOT in 56 TB patients, 20 latent TB infection (LTBI) and 30 BCG-vaccinated controls in comparison with the commercial T-SPOT. TB kit. Humoral response was evaluated by ELISA in 117 TB patients, 45 LTBI and 67 BCG-vaccinated controls, including all those who had T-cell assay, in comparison with a commercial IgG kit. RESULTS Rv1985c was specifically recognized by cellular and humoral responses from both TB and LTBI groups compared with healthy controls. Rv1985c IgG-ELISA achieved 52% and 62% sensitivity respectively, which outperformed the sensitivity of PATHOZYME-MYCO kit (34%) in detecting active TB (P = 0.011), whereas IFN-γ Rv1985c-ELISPOT achieved 71% and 55% sensitivity in detecting active and LTBI, respectively. Addition of Rv1985c increased sensitivities of ESAT-6, CFP-10 and ESAT-6/CFP-10 combination in detecting TB from 82.1% to 89.2% (P = 0.125), 67.9% to 87.5% (P < 0.001) and 85.7% to 92.9% (P = 0.125), respectively. CONCLUSIONS In conclusion, Rv1985c is a novel antigen which can be used to immunologically diagnose TB infection along with other immunodominant antigens among BCG-vaccinated population.
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Zeng J, Zhang L, Li Y, Wang Y, Wang M, Duan X, He ZG. Over-producing soluble protein complex and validating protein–protein interaction through a new bacterial co-expression system. Protein Expr Purif 2010; 69:47-53. [DOI: 10.1016/j.pep.2009.09.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Revised: 08/26/2009] [Accepted: 09/04/2009] [Indexed: 02/01/2023]
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Parkash O, Singh BP, Pai M. Regions of Differences Encoded Antigens as Targets for Immunodiagnosis of Tuberculosis in Humans. Scand J Immunol 2009; 70:345-57. [DOI: 10.1111/j.1365-3083.2009.02312.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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McEvoy CRE, van Helden PD, Warren RM, van Pittius NCG. Evidence for a rapid rate of molecular evolution at the hypervariable and immunogenic Mycobacterium tuberculosis PPE38 gene region. BMC Evol Biol 2009; 9:237. [PMID: 19769792 PMCID: PMC2758852 DOI: 10.1186/1471-2148-9-237] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Accepted: 09/21/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND PPE38 (Rv2352c) is a member of the large PPE gene family of Mycobacterium tuberculosis and related mycobacteria. The function of PPE proteins is unknown but evidence suggests that many are cell-surface associated and recognised by the host immune system. Previous studies targeting other PPE gene members suggest that some display high levels of polymorphism and it is thought that this might represent a means of providing antigenic variation. We have analysed the genetic variability of the PPE38 genomic region on a cohort of M. tuberculosis clinical isolates representing all of the major phylogenetic lineages, along with the ancestral M. tuberculosis complex (MTBC) member M. canettii, and supplemented this with analysis of publicly available whole genome sequences representing additional M. tuberculosis clinical isolates, other MTBC members and non tuberculous mycobacteria (NTM). Where possible we have extended this analysis to include the adjacent plcABC and PPE39/40 genomic regions. RESULTS We show that the ancestral MTBC PPE38 region comprises 2 homologous PPE genes (PPE38 and PPE71), separated by 2 esat-6 (esx)-like genes and that this structure derives from an esx/esx/PPE duplication in the common ancestor of M. tuberculosis and M. marinum. We also demonstrate that this region of the genome is hypervariable due to frequent IS6110 integration, IS6110-associated recombination, and homologous recombination and gene conversion events between PPE38 and PPE71. These mutations result in combinations of gene deletion, gene truncation and gene disruption in the majority of clinical isolates. These mutations were generally found to be IS6110 strain lineage-specific, although examples of additional within-lineage and even within-cluster mutations were observed. Furthermore, we provide evidence that the published M. tuberculosis H37Rv whole genome sequence is inaccurate regarding this region. CONCLUSION Our results show that this antigen-encoding region of the M. tuberculosis genome is hypervariable. The observation that numerous different mutations have become fixed within specific lineages demonstrates that this genomic region is undergoing rapid molecular evolution and that further lineage-specific evolutionary expansion and diversification has occurred subsequent to the lineage-defining mutational events. We predict that functional loss of these genes could aid immune evasion. Finally, we also show that the PPE38 region of the published M. tuberculosis H37Rv whole genome sequence is not representative of the ATCC H37Rv reference strain.
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Affiliation(s)
- Christopher RE McEvoy
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research/MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Faculty of Health Sciences, Stellenbosch University, PO Box 19063, Tygerberg, South Africa
| | - Paul D van Helden
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research/MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Faculty of Health Sciences, Stellenbosch University, PO Box 19063, Tygerberg, South Africa
| | - Robin M Warren
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research/MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Faculty of Health Sciences, Stellenbosch University, PO Box 19063, Tygerberg, South Africa
| | - Nicolaas C Gey van Pittius
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research/MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Faculty of Health Sciences, Stellenbosch University, PO Box 19063, Tygerberg, South Africa
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Chen J, Su X, Zhang Y, Wang S, Shao L, Wu J, Wang F, Zhang S, Wang J, Weng X, Wang H, Zhang W. Novel recombinant RD2- and RD11-encoded Mycobacterium tuberculosis antigens are potential candidates for diagnosis of tuberculosis infections in BCG-vaccinated individuals. Microbes Infect 2009; 11:876-85. [DOI: 10.1016/j.micinf.2009.05.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2009] [Revised: 05/12/2009] [Accepted: 05/13/2009] [Indexed: 10/20/2022]
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The transcriptional regulator Rv0485 modulates the expression of a pe and ppe gene pair and is required for Mycobacterium tuberculosis virulence. Infect Immun 2009; 77:4654-67. [PMID: 19651861 DOI: 10.1128/iai.01495-08] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The pe and ppe genes are unique to mycobacteria and are widely speculated to play a role in tuberculosis pathogenesis. However, little is known about how expression of these genes is controlled. Elucidating the regulatory control of genes found exclusively in mycobacteria, such as the pe and ppe gene families, may be key to understanding the success of this pathogen. In this study, we used a transposon mutagenesis approach to elucidate pe and ppe regulation. This resulted in the identification of Rv0485, a previously uncharacterized transcriptional regulator. Microarray and quantitative real-time PCR analysis confirmed that disruption of Rv0485 reduced the expression of the pe13 and ppe18 gene pair (Rv1195 and Rv1196), defined the Rv0485 regulon, and emphasized the lack of global regulation of pe and ppe genes. The in vivo phenotype of the Rv0485 transposon mutant strain (Rv0485::Tn) was investigated in the mouse model, where it was demonstrated that the mutation has minimal effect on bacterial organ burden. Despite this, disruption of Rv0485 allowed mice to survive for significantly longer, with substantially reduced lung pathology in comparison with mice infected with wild-type Mycobacterium tuberculosis. Infection of immune-deficient SCID mice with the Rv0485::Tn strain also resulted in extended survival times, suggesting that Rv0485 plays a role in modulation of innate immune responses. This is further supported by the finding that disruption of Rv0485 resulted in reduced secretion of proinflammatory cytokines by infected murine macrophages. In summary, we have demonstrated that disruption of a previously uncharacterized transcriptional regulator, Rv0485, results in reduced expression of pe13 and ppe18 and attenuation of M. tuberculosis virulence.
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Development and evaluation of a novel multiple-antigen ELISA for serodiagnosis of tuberculosis. Tuberculosis (Edinb) 2009; 89:278-84. [DOI: 10.1016/j.tube.2009.05.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Revised: 04/28/2009] [Accepted: 05/24/2009] [Indexed: 11/20/2022]
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Steingart KR, Dendukuri N, Henry M, Schiller I, Nahid P, Hopewell PC, Ramsay A, Pai M, Laal S. Performance of purified antigens for serodiagnosis of pulmonary tuberculosis: a meta-analysis. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2009; 16:260-76. [PMID: 19052159 PMCID: PMC2643545 DOI: 10.1128/cvi.00355-08] [Citation(s) in RCA: 141] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Revised: 11/04/2008] [Accepted: 11/24/2008] [Indexed: 11/20/2022]
Abstract
Serological antibody detection tests for tuberculosis may offer the potential to improve diagnosis. Recent meta-analyses have shown that commercially available tests have variable accuracies and a limited clinical role. We reviewed the immunodiagnostic potential of antigens evaluated in research laboratories (in-house) for the serodiagnosis of pulmonary tuberculosis and conducted a meta-analysis to evaluate the performance of comparable antigens. Selection criteria included the participation of at least 25 pulmonary tuberculosis patients and the use of purified antigens. Studies evaluating 38 kDa, MPT51, malate synthase, culture filtrate protein 10, TbF6, antigen 85B, alpha-crystallin, 2,3-diacyltrehalose, 2,3,6-triacyltrehalose, 2,3,6,6'-tetraacyltrehalose 2'-sulfate, cord factor, and TbF6 plus DPEP (multiple antigen) were included in the meta-analysis. The results demonstrated that (i) in sputum smear-positive patients, sensitivities significantly >or=50% were provided for recombinant malate synthase (73%; 95% confidence interval [CI], 58 to 85) and TbF6 plus DPEP (75%; 95% CI, 50 to 91); (ii) protein antigens achieved high specificities; (iii) among the lipid antigens, cord factor had the best overall performance (sensitivity, 69% [95% CI, 28 to 94]; specificity, 91% [95% CI, 78 to 97]); (iv) compared with the sensitivities achieved with single antigens (median sensitivity, 53%; range, 2% to 100%), multiple antigens yielded higher sensitivities (median sensitivity, 76%; range, 16% to 96%); (v) in human immunodeficiency virus (HIV)-infected patients who are sputum smear positive, antibodies to several single and multiple antigens were detected; and (vi) data on seroreactivity to antigens in sputum smear-negative or pediatric patients were insufficient. Potential candidate antigens for an antibody detection test for pulmonary tuberculosis in HIV-infected and -uninfected patients have been identified, although no antigen achieves sufficient sensitivity to replace sputum smear microscopy. Combinations of select antigens provide higher sensitivities than single antigens. The use of a case-control design with healthy controls for the majority of studies was a limitation of the review. Efforts are needed to improve the methodological quality of tuberculosis diagnostic studies.
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Affiliation(s)
- Karen R Steingart
- Francis J. Curry National Tuberculosis Center, University of California, San Francisco, 3180 18th Street, Suite 101, San Francisco, CA 94110-2028, USA.
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Wang J, Qie Y, Zhang H, Zhu B, Xu Y, Liu W, Chen J, Wang H. PPE protein (Rv3425) from DNA segment RD11 of Mycobacterium tuberculosis: a novel immunodominant antigen of Mycobacterium tuberculosis induces humoral and cellular immune responses in mice. Microbiol Immunol 2008; 52:224-30. [PMID: 18426397 DOI: 10.1111/j.1348-0421.2008.00029.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Subtractive DNA hybridization of pathogenic M. bovis and BCG, and comparative genome-wide DNA microarray analysis of M. tuberculosis H37Rv and BCG identified several RD, designated as RD1 to RD16, between M. tuberculosis and M. bovis on the one hand and BCG on the other. These regions cover 108 ORF of M. tuberculosis H37Rv, and are deleted from all 13 BCG sub-strains currently used as anti-tuberculosis vaccines in different parts of the world. In this study, we evaluated cellular and humoral immune response in C57BL/6 mice immunized with the PPE protein Rv3425, encoded by an ORF found in RD11 of M. tuberculosis. Rv3425 protein induced an increased Th1/Th2 type immune response in mice, characterized by an elevated concentration of IFN-gamma in antigen stimulated splenocyte culture and a strong IgG(1) antibody response. These results provide evidence on the immunogenicity of the PPE protein Rv3425 which, together with its reported immunodominant characteristics, imply that it may be a candidate for development of a vaccine for the control of TB.
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Affiliation(s)
- Jiuling Wang
- State Key Laboratory of Genetic Engineering, Institute of Genetics, Fudan University, Shanghai 200433, China
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Frequent homologous recombination events in Mycobacterium tuberculosis PE/PPE multigene families: potential role in antigenic variability. J Bacteriol 2008; 190:7838-46. [PMID: 18820012 DOI: 10.1128/jb.00827-08] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The PE and PPE (PE/PPE) multigene families of Mycobacterium tuberculosis are particularly GC-rich and share extensive homologous repetitive sequences. We hypothesized that they may undergo homologous recombination events, a mechanism rarely described in the natural evolution of mycobacteria. To test our hypothesis, we developed a specific oligonucleotide-based microarray targeting nearly all of the PE/PPE genes, aimed at detecting signals for homologous recombination. Such a microarray has never before been reported due to the multiplicity and highly repetitive and homologous nature of these sequences. Application of the microarray to a collection of M. tuberculosis clinical isolates (n = 33) representing prevalent spoligotype strain families in Tunisia allowed successful detection of six deleted genomic regions involving a total of two PE and seven PPE genes. Some of these deleted genes are known to be immunodominant or involved in virulence. The four precisely determined deletions were flanked by 400- to 500-bp stretches of nearly identical sequences lying mainly at the conserved N-terminal region of the PE/PPE genes. These highly homologous sequences thus serve as substrates to mediate both intergenic and intragenic homologous recombination events, indicating an important function in generating strain variation. Importantly, all recombination events yielded a new in-frame fusion chimeric gene. Hence, homologous recombination within and between PE/PPE genes likely increased their antigenic variability, which may have profound implications in pathogenicity and/or host adaptation. The finding of high prevalence (approximately 45% and approximately 58%) for at least two of the genomic deletions suggests that they likely confer advantageous biological attributes.
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Zvi A, Ariel N, Fulkerson J, Sadoff JC, Shafferman A. Whole genome identification of Mycobacterium tuberculosis vaccine candidates by comprehensive data mining and bioinformatic analyses. BMC Med Genomics 2008; 1:18. [PMID: 18505592 PMCID: PMC2442614 DOI: 10.1186/1755-8794-1-18] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Accepted: 05/28/2008] [Indexed: 12/19/2022] Open
Abstract
Background Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), infects ~8 million annually culminating in ~2 million deaths. Moreover, about one third of the population is latently infected, 10% of which develop disease during lifetime. Current approved prophylactic TB vaccines (BCG and derivatives thereof) are of variable efficiency in adult protection against pulmonary TB (0%–80%), and directed essentially against early phase infection. Methods A genome-scale dataset was constructed by analyzing published data of: (1) global gene expression studies under conditions which simulate intra-macrophage stress, dormancy, persistence and/or reactivation; (2) cellular and humoral immunity, and vaccine potential. This information was compiled along with revised annotation/bioinformatic characterization of selected gene products and in silico mapping of T-cell epitopes. Protocols for scoring, ranking and prioritization of the antigens were developed and applied. Results Cross-matching of literature and in silico-derived data, in conjunction with the prioritization scheme and biological rationale, allowed for selection of 189 putative vaccine candidates from the entire genome. Within the 189 set, the relative distribution of antigens in 3 functional categories differs significantly from their distribution in the whole genome, with reduction in the Conserved hypothetical category (due to improved annotation) and enrichment in Lipid and in Virulence categories. Other prominent representatives in the 189 set are the PE/PPE proteins; iron sequestration, nitroreductases and proteases, all within the Intermediary metabolism and respiration category; ESX secretion systems, resuscitation promoting factors and lipoproteins, all within the Cell wall category. Application of a ranking scheme based on qualitative and quantitative scores, resulted in a list of 45 best-scoring antigens, of which: 74% belong to the dormancy/reactivation/resuscitation classes; 30% belong to the Cell wall category; 13% are classical vaccine candidates; 9% are categorized Conserved hypotheticals, all potentially very potent T-cell antigens. Conclusion The comprehensive literature and in silico-based analyses allowed for the selection of a repertoire of 189 vaccine candidates, out of the whole-genome 3989 ORF products. This repertoire, which was ranked to generate a list of 45 top-hits antigens, is a platform for selection of genes covering all stages of M. tuberculosis infection, to be incorporated in rBCG or subunit-based vaccines.
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Affiliation(s)
- Anat Zvi
- Israel Institute for Biological Research, Ness Ziona 74100, Israel.
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Wang JL, Qie YQ, Zhu BD, Zhang HM, Xu Y, Wang QZ, Chen JZ, Liu W, Wang HH. Evaluation of a recombinant BCG expressing antigen Ag85B and PPE protein Rv3425 from DNA segment RD11 of Mycobacterium tuberculosis in C57BL/6 mice. Med Microbiol Immunol 2008; 198:5-11. [PMID: 18491134 DOI: 10.1007/s00430-008-0098-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Indexed: 11/25/2022]
Abstract
Antigen 85B (Ag85B) is an important immunodominant antigen of Mycobacterium tuberculosis, and is a very promising vaccine candidate molecule. Rv3425 is a member of the subgroup 3 of the PPE family, which does not exist in all BCG strains. In this study we constructed a new rBCG which included this united gene (Ag85B-Rv3425). The level of antigen-stimulated T cells expressing IFN-gamma was significantly higher in the C57BL/6 mice vaccinated with rBCG::Ag85B-Rv3425 than with BCG. In addition, the sera from mice immunized with rBCG::Ag85B-Rv3425 revealed an increase in the specific immunoglobulin G titers than that from mice immunized with BCG. Antigen specific IgG subclass analysis showed that rBCG::Ag85B-Rv3425 tended to facilitate IgG2a production, suggesting enhancement of predominant Th1 response which in turn may facilitate increased production of protective IFN-gamma. These results suggested that this rBCG::Ag85B-Rv3425 could be a strong vaccine candidate for further study.
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Affiliation(s)
- Jiu ling Wang
- Institute of Genetics, Fudan University, 200433, Shanghai, People's Republic of China
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Association of strong immune responses to PPE protein Rv1168c with active tuberculosis. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2008; 15:974-80. [PMID: 18400969 DOI: 10.1128/cvi.00485-07] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Accurate diagnosis of tuberculosis (TB) infection is critical for the treatment, prevention, and control of TB. Conventional diagnostic tests based on purified protein derivative (PPD) do not achieve the required diagnostic sensitivity. Therefore, in this study, we have evaluated the immunogenic properties of Rv1168c, a member of the PPE family, in comparison with PPD, which is routinely used in the tuberculin test, and Hsp60 and ESAT-6, well-known immunodominant antigens of Mycobacterium tuberculosis. In a conventional enzyme immunoassay, the recombinant Rv1168c protein displayed stronger immunoreactivity against the sera obtained from patients with clinically active TB than did PPD, Hsp60, or ESAT-6 and could distinguish TB patients from Mycobacterium bovis BCG-vaccinated controls. Interestingly, Rv1168c antigen permits diagnosis of smear-negative pulmonary TB as well as extrapulmonary TB cases, which are often difficult to diagnose by conventional tests. The immunodominant nature of Rv1168c makes it a promising candidate to use in serodiagnosis of TB. In addition, our studies also show that Rv1168c is a potent T-cell antigen which elicits a strong gamma interferon response in sensitized peripheral blood mononuclear cells obtained from TB patients.
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Rosenkrands I, Aagaard C, Weldingh K, Brock I, Dziegiel MH, Singh M, Hoff S, Ravn P, Andersen P. Identification of Rv0222 from RD4 as a novel serodiagnostic target for tuberculosis. Tuberculosis (Edinb) 2008; 88:335-43. [PMID: 18243798 DOI: 10.1016/j.tube.2007.12.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2007] [Revised: 11/29/2007] [Accepted: 12/14/2007] [Indexed: 11/25/2022]
Abstract
Forty-seven Mycobacterium tuberculosis genes from the 'regions of difference' RD2-7, RD9-13 and RD15 were cloned and expressed, and the purified recombinant proteins were screened for their serodiagnostic potential. Evaluation of six selected proteins in serum samples from Danish resident tuberculosis patients and healthy controls led to identification of Rv0222 as the most promising serodiagnostic antigen. Recognition of the Rv0222 was compared with the 38 kDa protein and a fusion protein of the RD1 proteins ESAT-6 and CFP10 in a serum panel from pulmonary tuberculosis (TB) patients from Uganda. The highest overall sensitivity was observed for Rv0222 compared to BCG-vaccinated non-endemic healthy controls as well as symptomatic endemic controls. Importantly, Rv0222 identified human immuno deficiency (HIV) virus-positive patients and HIV-negative patients with the same overall sensitivity. The results emphasize the importance of cut-off values in TB endemic regions based on endemic control individuals to diagnose active TB, and identify Rv0222 as a promising new antigen for serodiagnosis of TB in both HIV-negative and HIV-positive patients.
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Affiliation(s)
- Ida Rosenkrands
- Department of Infectious Disease Immunology, Statens Serum Institut, Artillerivej 5, DK-2300 Copenhagen S, Denmark.
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Functional role of the PE domain and immunogenicity of the Mycobacterium tuberculosis triacylglycerol hydrolase LipY. Infect Immun 2007; 76:127-40. [PMID: 17938218 DOI: 10.1128/iai.00410-07] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PE and PPE proteins appear to be important for virulence and immunopathogenicity in mycobacteria, yet the functions of the PE/PPE domains remain an enigma. To decipher the role of these domains, we have characterized the triacylglycerol (TAG) hydrolase LipY from Mycobacterium tuberculosis, which is the only known PE protein expressing an enzymatic activity. The overproduction of LipY in mycobacteria resulted in a significant reduction in the pool of TAGs, consistent with the lipase activity of this enzyme. Unexpectedly, this reduction was more pronounced in mycobacteria overexpressing LipY lacking the PE domain [LipY(deltaPE)], suggesting that the PE domain participates in the modulation of LipY activity. Interestingly, Mycobacterium marinum contains a protein homologous to LipY, termed LipY(mar), in which the PE domain is substituted by a PPE domain. As for LipY, overexpression of LipY(mar) in Mycobacterium smegmatis significantly reduced the TAG pool, and this was further pronounced when the PPE domain of LipY(mar) was removed. Fractionation studies and Western blot analysis demonstrated that both LipY and LipY(deltaPE) were mainly present in the cell wall, indicating that the PE domain was not required for translocation to this site. Furthermore, electron microscopy immunolabeling of LipY(deltaPE) clearly showed a cell surface localization, thereby suggesting that the lipase may interact with the host immune system. Accordingly, a strong humoral response against LipY and LipY(deltaPE) was observed in tuberculosis patients. Together, our results suggest for the first time that both PE and PPE domains can share similar functional roles and that LipY represents a novel immunodominant antigen.
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