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IUBMB Life Sep 2018Reporter strains have proven to be powerful tools to study Mycobacterium tuberculosis (Mtb) physiology. Transcriptional and translational reporter strains are engineered... (Review)
Review
Reporter strains have proven to be powerful tools to study Mycobacterium tuberculosis (Mtb) physiology. Transcriptional and translational reporter strains are engineered by fusing a readout gene, encoding a fluorescent, luminescent or enzymatic protein, downstream of a promoter or in-frame with a gene of interest. When the reporter is expressed, it generates a signal that acts as a synthetic phenotype, enabling the study of physiologies that might have otherwise been hidden. This review will discuss approaches for generating reporter strains in Mtb and how they can be used as tools for high-throughput genetic and small molecule screening and as biomarkers for examining Mtb responses to drug or immune stresses during animal infections. Fluorescent reporter strains have an added benefit in that they can be used for single-cell studies both in vitro and in vivo, thus enabling the study of mechanisms underlying phenotypic heterogeneity. Recent examples of the use of Mtb reporter strains will be presented with a focus on how they can be used as tools for drug discovery and development. © 2018 IUBMB Life, 70(9):818-825, 2018.
Topics: Animals; Antitubercular Agents; Drug Discovery; Genes, Reporter; Host-Pathogen Interactions; Humans; Mycobacterium tuberculosis; Tuberculosis
PubMed: 29707888
DOI: 10.1002/iub.1862 -
Revista Da Sociedade Brasileira de... 2017The lipid-rich cell wall of Mycobacterium tuberculosis is a dynamic structure that is involved in the regulation of the transport of nutrients, toxic host-cell effector... (Review)
Review
The lipid-rich cell wall of Mycobacterium tuberculosis is a dynamic structure that is involved in the regulation of the transport of nutrients, toxic host-cell effector molecules, and anti-tuberculosis drugs. It is therefore postulated to contribute to the long-term bacterial survival in an infected human host. Accumulating evidence suggests that M. tuberculosis remodels the lipid composition of the cell wall as an adaptive mechanism against host-imposed stress. Some of these lipid species (trehalose dimycolate, diacylated sulphoglycolipid, and mannan-based lipoglycans) trigger an immunopathologic response, whereas others (phthiocerol dimycocerosate, mycolic acids, sulpholipid-1, and di-and polyacyltrehalose) appear to dampen the immune responses. These lipids appear to be coordinately expressed in the cell wall of M. tuberculosis during different phases of infection, ultimately determining the clinical fate of the infection. This review summarizes the current state of knowledge on the metabolism, transport, and homeostatic or immunostatic regulation of the cell wall lipids, and their orchestrated interaction with host immune responses that results in bacterial clearance, persistence, or tuberculosis.
Topics: Cell Wall; Humans; Immunity, Innate; Lipid Metabolism; Lipids; Membrane Lipids; Membrane Transport Proteins; Mycobacterium tuberculosis
PubMed: 28327797
DOI: 10.1590/0037-8682-0230-2016 -
Applied Biochemistry and Biotechnology Feb 2017The host-pathogen interaction and involvement of calcium (Ca) signaling in tuberculosis infection is crucial and plays a significant role in pathogenesis. Ca is known as... (Review)
Review
The host-pathogen interaction and involvement of calcium (Ca) signaling in tuberculosis infection is crucial and plays a significant role in pathogenesis. Ca is known as a ubiquitous second messenger that could control multiple processes and is included in cellular activities like division, motility, stress response, and signaling. However, Ca is thought to be a regulative molecule in terms of TB infection but its binding relation with proteins/substrates molecules which are influenced with Ca concentrations in host-pathogen interaction requires attention. So, in this review, our primary goal is to focus on some Ca substrates/proteins and their imperative involvement in pathogenesis, which is unclear. We have discussed several Ca-binding substrate and protein that affect intracellular mechanism of infected host cell. The major involvement of these proteins/substrates including calmodulin (CaM), calpain, annexin, surfactant protein A (SP-A), surfactant protein D (SP-D), calprotectin (MRP8/14), and PE_PGRS family protein are considered to be significant; however, their detailed understanding in mycobacterium infection is limited. In this aspect, this study will help in adding up our understanding in TB biology and additionally in the development of new therapeutic approach to reduce TB pandemic worldwide.
Topics: Calcium; Calcium Signaling; Cell Survival; Host-Pathogen Interactions; Mycobacterium tuberculosis; Virulence Factors
PubMed: 27660000
DOI: 10.1007/s12010-016-2247-9 -
Journal of Microbiological Methods Apr 2016Tuberculosis (TB) is an infectious bacterial disease caused by Mycobacterium tuberculosis. Despite global TB eradication efforts, it is still a global public health... (Review)
Review
Tuberculosis (TB) is an infectious bacterial disease caused by Mycobacterium tuberculosis. Despite global TB eradication efforts, it is still a global public health concern, especially in low- and middle-income countries. Most of the active TB infections are curable with early diagnosis and appropriate treatment, but drug-resistant TB is difficult and expensive to treat in immunocompetent as well as immunocompromised individuals. Thus, rapid, economic, and accurate point-of care tools for TB diagnosis are required urgently. This review describes the history of M. tuberculosis detection methods up to date and the recent advances using nanotechnology for point-of-care testing of TB diagnosis.
Topics: Diagnostic Techniques and Procedures; Humans; Mycobacterium tuberculosis; Tuberculosis
PubMed: 26853124
DOI: 10.1016/j.mimet.2016.02.007 -
Advances in Experimental Medicine and... 2017Tuberculosis is caused by different groups of bacteria belonging to the Mycobacterium tuberculosis complex (MTBC). The combined action of human factors, environmental... (Review)
Review
Tuberculosis is caused by different groups of bacteria belonging to the Mycobacterium tuberculosis complex (MTBC). The combined action of human factors, environmental conditions and bacterial virulence determine the extent and form of human disease. MTBC virulence is a composite of different clinical phenotypes such as transmission rate and disease severity among others. Clinical phenotypes are also influenced by cellular and immunological phenotypes. MTBC phenotypes are determined by the genotype, therefore finding genotypes responsible for clinical phenotypes would allow discovering MTBC virulence factors. Different MTBC strains display different cellular and clinical phenotypes. Strains from Lineage 5 and Lineage 6 are metabolically different, grow slower, and are less virulent. Also, at least certain groups of Lineage 2 and Lineage 4 strains are more virulent in terms of disease severity and human-to-human transmission. Because phenotypic differences are ultimately caused by genotypic differences, different genomic loci have been related to various cellular and clinical phenotypes. However, defining the impact of specific bacterial genomic loci on virulence when other bacterial determinants, human and environmental factors are also impacting the phenotype would contribute to a better knowledge of tuberculosis virulence and ultimately benefit tuberculosis control.
Topics: Africa; Genetic Loci; Genetic Variation; Genome, Bacterial; Genotype; Host-Pathogen Interactions; Humans; Latin America; Mutation Rate; Mycobacterium tuberculosis; Phenotype; Phylogeny; Phylogeography; Severity of Illness Index; Tuberculosis; Virulence; Virulence Factors
PubMed: 29116631
DOI: 10.1007/978-3-319-64371-7_5 -
Cold Spring Harbor Perspectives in... Mar 2015The mycobacterial bacillus is encompassed by a remarkably elaborate cell wall structure. The mycolyl-arabinogalactan-peptidoglycan (mAGP) complex is essential for the... (Review)
Review
The mycobacterial bacillus is encompassed by a remarkably elaborate cell wall structure. The mycolyl-arabinogalactan-peptidoglycan (mAGP) complex is essential for the viability of Mycobacterium tuberculosis and maintains a robust basal structure supporting the upper "myco-membrane." M. tuberculosis peptidoglycan, although appearing to be unexceptional at first glance, contains a number of unique molecular subtleties that become particularly important as the TB-bacilli enters into nonreplicative growth during dormancy. Arabinogalactan, a highly branched polysaccharide, serves to connect peptidoglycan with the outer mycolic acid layer, and a variety of unique glycolsyltransferases are used for its assembly. In this review, we shall explore the microbial chemistry of this unique heteropolysacchride, examine the molecular genetics that underpins its fabrication, and discuss how the essential biosynthetic process might be exploited for the development of future anti-TB chemotherapies.
Topics: Cell Wall; Galactans; Humans; Mycobacterium tuberculosis; Peptidoglycan; Sensitivity and Specificity; Virulence
PubMed: 25818664
DOI: 10.1101/cshperspect.a021113 -
Tuberculosis (Edinburgh, Scotland) Jul 2019The currently available methods are unable to directly detect dormant forms of Mycobacterium tuberculosis (Mtb) in vivo. The persistence of Mtb in the host body is... (Review)
Review
The currently available methods are unable to directly detect dormant forms of Mycobacterium tuberculosis (Mtb) in vivo. The persistence of Mtb in the host body is detectable only in an indirect manner via the immunological response to Mtb-specific antigens. It is commonly recognized that the pathogen prevalently exists in the human body in a latent stage. Additional research efforts focusing on the Mtb dormancy are needed for development of sterilizing drugs, which are necessary to control LTBI and stop TB epidemic. To this end, the in vitro models of Mtb dormancy may be useful. This review briefly describes the phenomenon of Mtb dormancy and its role in the context of tuberculosis as a persistent bacterial infection; then the article characterizes in details the in vitro methods used for modeling the Mtb dormancy in bacterial cultures.
Topics: Antibiotics, Antitubercular; Bacterial Physiological Phenomena; Cell Proliferation; Drug Tolerance; Gene Expression Regulation; Humans; Latent Tuberculosis; Models, Biological; Mycobacterium tuberculosis
PubMed: 31378272
DOI: 10.1016/j.tube.2019.05.005 -
EBioMedicine Oct 2021
Topics: Host-Pathogen Interactions; Humans; Mycobacterium avium; Mycobacterium tuberculosis; Tuberculosis
PubMed: 34717837
DOI: 10.1016/j.ebiom.2021.103659 -
Tuberculosis (Edinburgh, Scotland) May 2017Linezolid (LZD) is not commonly used for treating tuberculosis (TB), but in some patients with drug-resistant TB it is being used. However, the in vitro LZD activity,...
BACKGROUND
Linezolid (LZD) is not commonly used for treating tuberculosis (TB), but in some patients with drug-resistant TB it is being used. However, the in vitro LZD activity, in combination with rifampicin (RIF) against Mycobacterium tuberculosis has not been fully elucidated.
AIMS
The aim of this study was to evaluate the in vitro activity of RIF/LZD combination against M. tuberculosis clinical isolates.
MATERIALS AND METHODS
The activity of the RIF/LZD combination was firstly determined in M. tuberculosis HRv, 14 susceptible, 9 isoniazid nonresistant and 14 multi-drug resistant (MDR) M. tuberculosis clinical isolates by modified checkerboard assay, Resazurin Drugs Combination Microtiter Assay (REDCA). After, the Time Kill Curve Assay, at 0.5 × MIC of drugs, in combination and alone, was performed in M. tuberculosis HRv and 8 (20.5%) of those clinical isolates, which the RIF/LZD combination showed to have synergistic effect by the checkerboard assay.
RESULTS AND CONCLUSION
By Time Kill Curve Assay, we could observe in M. tuberculosis HRv and susceptible isolates, that LZD alone, at sub inhibitory concentration, has poor effect on the bacillus death. In some cases, the bacillus growth stayed constant while in others showed regrowth at the eighth day of drug exposure. RIF alone exhibits potent concentration-dependent bactericidal activity, and was strongly dependent by the drug exposure time. The RIF/LZD combination accomplished a bacteriostatic effect in the reference strain and susceptible isolates. For the RIF resistant isolates, the RIF/LZD combination did not enhance the effect in killing bacillus. In this sense, additional, in vitro and in vivo studies are needed to evaluate the effect of RIF/LZD combination in order to better understand the adjunctive action of LZD in the treatment of TB and prevent the emergence of mutants with resistance to the available anti-TB drugs.
Topics: Antitubercular Agents; Drug Resistance, Multiple, Bacterial; Drug Synergism; Drug Therapy, Combination; Genotype; Linezolid; Microbial Sensitivity Tests; Microbial Viability; Mycobacterium tuberculosis; Rifampin; Time Factors
PubMed: 28454646
DOI: 10.1016/j.tube.2017.02.004 -
Journal of Global Antimicrobial... Mar 2018In this brief review, various forms of drug-resistant tuberculosis (DR-TB) are discussed. The focus of the study is to highlight morphological alterations of DR-TB... (Review)
Review
In this brief review, various forms of drug-resistant tuberculosis (DR-TB) are discussed. The focus of the study is to highlight morphological alterations of DR-TB bacilli at the cellular level.
Topics: Antitubercular Agents; Fimbriae, Bacterial; Genome, Bacterial; Humans; Mycobacterium tuberculosis; Tuberculosis, Multidrug-Resistant
PubMed: 29042338
DOI: 10.1016/j.jgar.2017.10.006