Major programs at the CTR:
- Establishing a repository of CRISPRi mutant strains of mycobacteria:
Center for Tuberculosis Research has pioneered in designing the CRISPRi tool for conditional silencing of genes in mycobacteria. Currently, Principal Investigators at the centre are setting up the repository of CRISPRi mutants to aid researchers within and outside India. So far, ~500 knockdown strains of Mycobacterium tuberculosis and various other mycobacterial species as well as the respective plasmid constructs have been deposited in the repository, which are freely available to outside users. To our knowledge, this is the largest collect of CRISPRi mutant strains in the country targeting a variety of mycobacterial genes. These resources have been shared worldwide with investigators at the premier institutions in different countries including India such as United States of America, Poland, Czech Republic, Brazil, Norway, Germany, China, Spain, Colombia, United Kingdom, Italy and France.
- Identification of novel drug targets in the tuberculosis pathogen:
A thorough analysis of the genome sequence of the tuberculosis pathogen M. tuberculosis reveals multiple genes of unknown functions, several of which are predicted essential for the pathogen’s survival. With the help of CRISPRi-based gene silencing technology, the Centre for Tuberculosis Research is involved in studying the function of unknown genes. Primary emphasis is given to those involved in the protein homeostasis machinery. The ultimate goal of his research is to decipher the function of uncharacterized genes of essential nature to comprehend their involvement in bacterial susceptibility to antibiotics, and explore some of these as novel therapeutic targets
- Discovery, design and development of novel therapeutics for tuberculosis:
New drugs with a novel mechanism of action are urgently needed to tackle the issue of drug resistant tuberculosis (DR-TB). The identified new molecules should be effective against DR- TB and target a pathway that is essential, druggable and distinct from the known tuberculosis drug targets. At the Centre for Tuberculosis research assays have been standardized to perform phenotypic, target and macrophage-based screening to identify novel antitubercular agents. Using these screening assays, we have identified small molecules that possess novel mechanism of action and show synergy with first-line anti-tuberculosis drugs. The identified small molecules are also active against intracellular drug-sensitive and drug resistant M. tuberculosis strains. Experiments are in progress to further optimize identified lead molecules to enhance their antimycobacterial activity
- Shortening of anti-tuberculosis drug regimen by targeting persisters
One of the major issues with tuberculosis therapy is the long treatment duration causing several toxic effects on humans. More than 50% of active tuberculosis patients voluntarily stop drugs in the mid-way leading to sustained transmission of the disease and emergence of drug- resistance in the pathogen. Depending on the drug susceptibility profile, the treatment duration of tuberculosis can extend from 6 months to 2 years. This protracted drug regimen is attributed to a supposedly non-replicating and metabolically inert subset of a population, called ‘persisters’. The mechanisms underlying stochastic generation and enrichment of persisters is not elucidated well. It is believed that molecules targeting persisters would potentiate the current therapy by shortening the duration. Efforts are ongoing to decipher the underlying mechanisms of persisters formation, with a long-term goal to identify therapeutic molecules against these specialized population of the pathogen.
- Understanding the host-response to the tuberculosis pathogen and the underlying mechanisms of disease pathogenesis:
The pathogenesis of tuberculosis involves a complex interplay of interactions between host and bacteria. The Centre for Tuberculosis research has standardised methods to generate mutant strains and perform animal infection studies in mice, guinea pigs to identify virulence factors. Using these approaches the centre has identified novel metabolic pathways to be essential for M. tuberculosis to establish disease in animals. These include toxin-antitoxin systems, enzyme involved in inorganic polyphosphate metabolism, transcription factors, enzymes involved in itaconate dissimilation pathway and various conserved hypothetical proteins that are induced in stress conditions. Experiments are in progress to further delineate the mechanisms by which these pathways contribute to disease pathogenesis.
Using in-house developed CRISPRi mutant strains, the Principal Investigators at THSTI are studying response of host macrophages to M. tuberculosis infection. The study aims at identifying and understanding role of key virulent genes that are critical for the manipulation of host metabolic pathways during infection.
- Pathogen-derived extracellular vesicles-based diagnostics:
Similar to most bacteria, mycobacteria also generate membrane-derived extracellular vesicles. These nanostructures pack themselves with proteins and small molecules that have the propensity to be generated and transported from the very site of infections. Additionally, infected hosts sample pathogen molecules, load them into host-derived extracellular vesicles (exosomes) and translocate to different organs of the body for immune onslaught. Given the nature of both pathogen and host extracellular vesicles have several pathogen molecules, efforts are on to exploit these as novel pathogen biomarkers for superior diagnosis especially in extra- pulmonary tuberculosis patients.
- Significance and implication of fatty liver on progression of tuberculosis as well as treatment outcome:
Fatty liver or hepatic steatosis is a clinical condition where liver cells have abnormal retention of fat or lipid bodies. Hepatic steatosis is not a disease but a well-known risk factor for multiple metabolic diseases such as diabetes, Non-alcoholic steatohepatitis (NASH), cardiovascular complications or chronic kidney diseases. Unfortunately, the prevalence of fatty liver is epidemic. There are reports highlighting higher susceptibility to tuberculosis infection as well as higher mortality due to the prevalence of diabetes. However, not much is understood about the implication of fatty liver on tuberculosis pathogenesis and treatment outcome. Additionally, fatty liver is also prone to drug-induced liver injuries (DILI) which is a serious concern due to the long treatment regime of Mtb infection. The tuberculosis research group at THSTI has an interest in determining and delineating the possible association and implication of fatty liver on tuberculosis pathogenesis and treatment outcome
Name of faculty members and Scientists
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