National Institute for Research in Tuberculosis NIRT

Chennai, India

National Institute for Research in Tuberculosis NIRT

Chennai, India
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Unissa A.N.,National Institute for Research in Tuberculosis NIRT | Sukumar S.,National Institute for Research in Tuberculosis NIRT | Hanna L.E.,National Institute for Research in Tuberculosis NIRT
Tuberculosis and Respiratory Diseases | Year: 2017

Background: N-acetyl transferase (NAT) inactivates the pro-drug isoniazid (INH) to N-acetyl INH through a process of acetylation, and confers low-level resistance to INH in Mycobacterium tuberculosis (MTB). Similar to NAT of MTB, NAT2 in humans performs the same function of acetylation. Rapid acetylators, may not respond to INH treatment efficiently, and could be a potential risk factor, for the development of INH resistance in humans. Methods: To understand the contribution of NAT of MTB and NAT2 of humans in developing INH resistance using in silico approaches, in this study, the wild type (WT) and mutant (MT)-NATs of MTB, and humans, were modeled and docked, with substrates and product (acetyl CoA, INH, and acetyl INH). The MT models were built, using templates 4BGF of MTB, and 2PFR of humans. Results: On the basis of docking results of MTB-NAT, it can be suggested that in comparison to the WT, binding affinity of MT-G207R, was found to be lower with acetyl CoA, and higher with acetyl-INH and INH. In case of MT-NAT2 from humans, the pattern of score with respect to acetyl CoA and acetyl-INH, was similar to MT-NAT of MTB, but revealed a decrease in INH score. Conclusion: In MTB, MT-NAT revealed high affinity towards acetyl-INH, which can be interpreted as increased formation of acetyl-INH, and therefore, may lead to INH resistance through inactivation of INH. Similarly, in MT-NAT2 (rapid acetylators), acetylation occurs rapidly, serving as a possible risk factor for developing INH resistance in humans. Copyright © 2017 The Korean Academy of Tuberculosis and Respiratory Diseases. All rights reserved.


Sweetline Anne N.,Tamil Nadu Veterinary and Animal Sciences University | Ronald B.S.M.,Veterinary College and Research Institute | Kumar T.M.A.S.,Tamil Nadu Veterinary and Animal Sciences University | Kannan P.,National Institute for Research In Tuberculosis NIRT | Thangavelu A.,Tamil Nadu Veterinary and Animal Sciences University
Veterinary Microbiology | Year: 2017

Bovine tuberculosis continued to be a re-emerging problem in some countries especially in endemic areas due to the fact that human and animal health surveillance system is not adopted to diagnose the infection. This crisis can be attributed due to sharing of the same habitat especially in rural areas. In the present study, a total of 148 samples were collected from cattle for isolation over a period of 3 years from cattle with and without lesions, of which 67 isolates were obtained by culture. Fifty one isolates were identified as Mycobacterium tuberculosis complex (MTBC) by IS6110 PCR of which 43 (84.3%) were identified as M. tuberculosis and 08 (15.6%) were identified as M. bovis by using 12.7 kb fragment multiplex PCR. Among this, 31 isolates which were positive for IS6110 PCR were subjected to spoligotyping and revealed 28 isolates belonging to MANU1 strain of M. tuberculosis. This study clearly indicates that high prevalence of M. tuberculosis than M. bovis in bovine was identified by means of culture and by molecular methods M. tuberculosis can affect cattle producing lesion in contradiction to the earlier thoughts. This study speculates that M. tuberculosis MANU1 strain infection in cattle could be due to spill over from human or other non specific hosts in tuberculosis endemic areas. Though bovine tuberculosis due to M. tuberculosis in cattle is not considered a serious threat worldwide, in countries where human TB is endemic, M. tuberculosis infection of cattle needs to be considered. © 2016 Elsevier B.V.


Kandasamy S.,National Institute for Research in Tuberculosis NIRT | Narayanan S.,National Institute for Research in Tuberculosis NIRT
Microbiological Research | Year: 2015

Serine/threonine protein kinases play a major role in peptidoglycan biosynthesis in Mycobacterium tuberculosis. To explore the mechanism in detail, in the present study, we have constructed a double knockout (DKO) strain lacking pknI and dacB2 in M. tuberculosis. Initially, we analyzed the colony morphology and found that the DKO strain showed smoother colony morphology on solid agar and irregular shape in transmission electron microscopy. In addition, the DKO strain exhibits defective biofilm and cord formation. The DKO strain was found to be hypersensitive to cell wall damaging agents such as lysozyme, malachite green, ethidium bromide and to isoniazid, a first line anti-TB drug. In conclusion, our data suggest that both pknI and dacB2 play an important role in the maintenance of colony morphology, cell wall permeability and integrity of M. tuberculosis. © 2014 Elsevier GmbH.


Kubler A.,Imperial College London | Kubler A.,Johns Hopkins University | Luna B.,Johns Hopkins University | Larsson C.,Umeå University | And 26 more authors.
Journal of Pathology | Year: 2015

Active tuberculosis (TB) often presents with advanced pulmonary disease, including irreversible lung damage and cavities. Cavitary pathology contributes to antibiotic failure, transmission, morbidity and mortality. Matrix metalloproteinases (MMPs), in particular MMP-1, are implicated in TB pathogenesis. We explored the mechanisms relating MMP/TIMP imbalance to cavity formation in a modified rabbit model of cavitary TB. Our model resulted in consistent progression of consolidation to human-like cavities (100% by day 28), with resultant bacillary burdens (>107 CFU/g) far greater than those found in matched granulomatous tissue (105 CFU/g). Using a novel, breath-hold computed tomography (CT) scanning and image analysis protocol, we showed that cavities developed rapidly from areas of densely consolidated tissue. Radiological change correlated with a decrease in functional lung tissue, as estimated by changes in lung density during controlled pulmonary expansion (R2 = 0.6356, p < 0.0001). We demonstrated that the expression of interstitial collagenase (MMP-1) was specifically greater in cavitary compared to granulomatous lesions (p < 0.01), and that TIMP-3 significantly decreased at the cavity surface. Our findings demonstrated that an MMP-1/TIMP imbalance is associated with the progression of consolidated regions to cavities containing very high bacterial burdens. Our model provided mechanistic insight, correlating with human disease at the pathological, microbiological and molecular levels. It also provided a strategy to investigate therapeutics in the context of complex TB pathology. We used these findings to predict a MMP/TIMP balance in active TB and confirmed this in human plasma, revealing the potential of MMP/TIMP levels as key components of a diagnostic matrix aimed at distinguishing active from latent TB (PPV = 92.9%, 95% CI 66.1-99.8%, NPV = 85.6%; 95% CI 77.0-91.9%). © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.


Kandasamy S.,National Institute for Research in Tuberculosis NIRT | Hassan S.,National Institute for Research in Tuberculosis NIRT | Gopalaswamy R.,National Institute for Research in Tuberculosis NIRT | Narayanan S.,National Institute for Research in Tuberculosis NIRT
Journal of Molecular Graphics and Modelling | Year: 2014

Tuberculosis is caused by Mycobacterium tuberculosis, an intracellular pathogen. PknI is one of the 11 functional Serine/Threonine Protein Kinases which is predicted to regulate the cell division of M. tuberculosis. In order to find newer drugs and vaccine we need to understand the pathogenesis of the disease. We have used the bioinformatics approach to identify the functionally active residues of PknI and to confirm the same with wet lab experiments. In the current study, we have created homology model for PknI and have done comparative structural analysis of PknI with other kinases. Molecular docking studies were done with a library of kinase inhibitors and T95 was found as the potent inhibitor for PknI. Based on structure based pharmacophore analysis of kinase substrate complexes, Lys 41 along with Asp90, Val92 and Asp96 were identified as functionally important residues. Further, we used site directed mutagenesis technique to mutate Lys 41 to Met resulting in defective cell division of Mycobacterium smegmatis mc2. Overall, the proposed model together with its binding features gained from pharmacophore docking studies helped in identifying ligand inhibitor specific to PknI which was confirmed by laboratory experiments.


Dinesh S.,University of Madras | Menon T.,University of Madras | Hanna L.E.,National Institute for Research in Tuberculosis NIRT | Suresh V.,Annamalai University | And 2 more authors.
International Journal of Biological Macromolecules | Year: 2016

Sargassum swartzii, a marine brown algae with wide range of biological properties belongs to the family Sargassaceae. Bioactive fucoidan fractions (CFF, FF1 and FF2) were isolated from S. swartzii and characterized by linear gradient anion-exchange chromatography and FT-IR. The characterized fucoidan fractions contained mainly sugars, sulfate and uronic acid. In the present study, anti-HIV-1 property of the fucoidan fractions was investigated. Fraction FF2 was found to exhibit significant anti-HIV-1 activity at concentrations of 1.56 and 6.25 μg/ml as observed by >50% reduction in HIV-1 p24 antigen levels and reverse transcriptase activity. Fucoidan fractions have no cytotoxic effects on PBMCs at the concentration range of 1.56-1000 μg/ml. These results suggest that fucoidan fractions could have inhibitory activity against HIV and has potential as an anti-HIV-1 agent. © 2015 Elsevier B.V.


PubMed | Veterinary College and Research Institute, National Institute for Research In Tuberculosis NIRT and Tamil Nadu Veterinary and Animal Sciences University
Type: | Journal: Veterinary microbiology | Year: 2017

Bovine tuberculosis continued to be a re-emerging problem in some countries especially in endemic areas due to the fact that human and animal health surveillance system is not adopted to diagnose the infection. This crisis can be attributed due to sharing of the same habitat especially in rural areas. In the present study, a total of 148 samples were collected from cattle for isolation over a period of 3 years from cattle with and without lesions, of which 67 isolates were obtained by culture. Fifty one isolates were identified as Mycobacterium tuberculosis complex (MTBC) by IS6110 PCR of which 43 (84.3%) were identified as M. tuberculosis and 08 (15.6%) were identified as M. bovis by using 12.7kb fragment multiplex PCR. Among this, 31 isolates which were positive for IS6110 PCR were subjected to spoligotyping and revealed 28 isolates belonging to MANU1 strain of M. tuberculosis. This study clearly indicates that high prevalence of M. tuberculosis than M. bovis in bovine was identified by means of culture and by molecular methods M. tuberculosis can affect cattle producing lesion in contradiction to the earlier thoughts. This study speculates that M. tuberculosis MANU1 strain infection in cattle could be due to spill over from human or other non specific hosts in tuberculosis endemic areas. Though bovine tuberculosis due to M. tuberculosis in cattle is not considered a serious threat worldwide, in countries where human TB is endemic, M. tuberculosis infection of cattle needs to be considered.


PubMed | National Institute for Research in Tuberculosis NIRT, Kakatiya University and International Medical University
Type: Journal Article | Journal: Bioorganic & medicinal chemistry letters | Year: 2016

Development of multidrug resistant (MDR) and extensively drug resistant (XDR) tuberculosis (TB) has been considered as major health burden, globally. In order to develop novel, potential molecules against drug resistant TB, twenty two (22) new 3-substituted-7-benzyl-5,6,7,8-tetrahydropyrido[4,3:4,5]thieno[2,3-d]pyrimidin-4(3H)-one (6a-k) and 3-substituted-7-benzyl-2-methyl-5,6,7,8-tetrahydropyrido[4,3:4,5]thieno[2,3-d]pyrimidin-4(3H)-one (7a-k) derivatives were designed and synthesized by using appropriate synthetic protocols. Pantothenate synthetase (PS) was considered as the target for the molecular docking studies and evaluated the binding pattern at active site, as PS plays a significant role in the biosynthesis of pantothenate in Mycobacterium tuberculosis (MTB). The preliminary in vitro antibacterial screening of test compounds was carried out against two strains of Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Klebsiella pneumoniae) bacteria. The antimycobacterial screening was performed against MTB H37Rv and an isoniazid-resistant clinical isolate of MTB. The compounds 6b, 6c, 6d, 6k, 7b, 7c, 7d and 7k exhibited promising antibacterial activity MIC in the range of 15-73 M against all bacterial strains used and compounds 6d and 7b showed antimycobacterial activity (IC50 <340 M in LRP assay) and (MIC <9 M in broth microdilution method).


PubMed | National Institute for Research in Tuberculosis NIRT
Type: | Journal: BioMed research international | Year: 2015

Mutation at codon 315 of katG gene is the major cause for isoniazid (INH) resistance in Mycobacterium tuberculosis (M. tuberculosis). Substitution at codon 315 of katG gene was analyzed in 85 phenotypically resistant isolates collected from various parts of southern India by direct sequencing method. The obtained results were interpreted in the context of minimum inhibitory concentration (MIC) of INH. Of the 85 phenotypically resistant isolates, 56 (66%) were also correlated by the presence of resistance mutations in the katG gene; 47 of these isolates had ACC, 6 had AAC, 2 had ATC, and one had CGC codon. The frequency of Ser315 substitution in katG gene was found to be higher (70%) amongst multidrug-resistant (MDR) strains than among non-MDR (61%) INH-resistant isolates. Further, the frequency of mutations was found to be greater (74%) in isolates with higher MIC values in contrast to those isolates with low MIC values (58%). Therefore, the study identified high prevalence of Ser315Thr substitution in katG gene of INH-resistant isolates from south India. Also, isolates harboring this substitution were found to be associated with multidrug and high level INH resistance.


PubMed | Sathyabama University, National Institute for Research in Tuberculosis NIRT, University of Madras and Annamalai University
Type: | Journal: International journal of biological macromolecules | Year: 2015

Sargassum swartzii, a marine brown algae with wide range of biological properties belongs to the family Sargassaceae. Bioactive fucoidan fractions (CFF, FF1 and FF2) were isolated from S. swartzii and characterized by linear gradient anion-exchange chromatography and FT-IR. The characterized fucoidan fractions contained mainly sugars, sulfate and uronic acid. In the present study, anti-HIV-1 property of the fucoidan fractions was investigated. Fraction FF2 was found to exhibit significant anti-HIV-1 activity at concentrations of 1.56 and 6.25 g/ml as observed by >50% reduction in HIV-1 p24 antigen levels and reverse transcriptase activity. Fucoidan fractions have no cytotoxic effects on PBMCs at the concentration range of 1.56-1000 g/ml. These results suggest that fucoidan fractions could have inhibitory activity against HIV and has potential as an anti-HIV-1 agent.

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