Mycobacterium Tuberculosis Strains Research Articles

Molecular docking, molecular dynamics simulations and binding free energy studies of interactions between Mycobacterium tuberculosis Pks13, PknG and bioactive constituents of extremophilic bacteria

Mycobacterial pathogens present a significant challenge to disease control efforts globally due to their inherent resistance to multiple antibiotics. The rise of drug-resistant strains of Mycobacterium tuberculosis has prompted an urgent need for innovative therapeutic solutions. One promising way to discover new tuberculosis drugs is by utilizing natural products from the vast biochemical space. Multidisciplinary methods can used to harness the bioactivity of these natural products. This study aimed to evaluate the antimycobacterial efficacy of functional crude extracts from bacteria isolated from gold mine tailings in South Africa. Bacterial strains were identified using 16S rRNA sequencing. The crude extracts obtained from the bacteria were tested against Mycobacterium tuberculosis H37Rv, Mycobacterium smegmatis mc2155, and Mycobacterium aurum A+. Untargeted HPLC-qTOF and molecular networking were used to identify the functional constituents present in extracts that exhibited inhibitory activity. A virtual screening workflow (VSW) was used to filter compounds that were strong binders to Mycobacterium tuberculosis Pks13 and PknG. The ligands returned from the VSW were subjected to optimization using density functional theory (DFT) at M06-2X/6-311++ (d,p) level of theory and basis set implemented in Gaussian16 Rev.C01. The optimized ligands were re-docked against Mycobacterium tuberculosis Pks13 and PknG. Molecular dynamics simulation and molecular mechanics generalized born surface area were used to evaluate the stability of the protein–ligand complexes formed by the identified hits. The hit that showed promising binding characteristics was virtually modified through multiple synthetic routes using reaction-driven enumeration. Three bacterial isolates showed significant activity against the two strains of Mycobacterium, while only two, Bacillus subtilis and Bacillus licheniformis, exhibited activity against both Mycobacterium tuberculosis H37Rv, Mycobacterium smegmatis mc2155, and Mycobacterium aurum A+. The tentatively identified compounds from the bacterial crude extracts belonged to various classes of natural compounds associated with antimicrobial activity. Two compounds, cyclo-(L-Pro-4-OH-L-Leu) and vazabitide A, showed strong binding against PknG and Pks13, with pre-MD MM-GBSA values of − 42.8 kcal/mol and − 47.6 kcal/mol, respectively. The DFT-optimized compounds exhibited the same docking scores as the ligands optimized using the OPSL-4 force field. After modifying vazabitide A, its affinity to the Pks13 binding site increased to − 85.8 kcal/mol, as revealed by the post-MD MM-GBSA analysis. This study highlights the potential of bacteria isolates from gold mine tailings as a source of new scaffolds for designing and optimizing anti-Mycobacterium agents. These agents synthesized in-silico can be further tested in-vitro to evaluate their efficacy.

An Exploratory Review of the Potential of Lytic Proteins and Bacteriophages for the Treatment of Tuberculosis.

Tuberculosis (TB) is a highly prevalent infectious disease that causes more than 1.5 million deaths a year. More than 25% of TB deaths occur in Africa, and TB is South Africa's leading cause of death, with about 89,000 people dying of it yearly. The emergence of multidrug-resistant TB (MDR-TB) poses a significant threat to health security and could reverse the positive gains already made in the fight against TB. Antibiotic treatments are available, but side effects and the alarming increase in the prevalence of drug-resistant strains of Mycobacterium tuberculosis (Mtb) will compromise the control of the spread and treatment of the disease. A promising option is to employ specialized enzymes encoded by bacteriophages, which destroy bacterial cell membranes and walls to treat tuberculosis. Phage therapy against bacteria is a known treatment that is now reemerging with lytic proteins. These proteins provide an alternative means to treat infectious diseases where conventional antibiotic regimens do not meet the requirements. This review explores and discusses the potential of lytic protein therapy as an antimicrobial strategy against M. tuberculosis and multidrug-resistant tuberculosis.

Genetic mechanisms of co-emergence of INH-resistant Mycobacterium tuberculosis strains during the standard course of antituberculosis therapy.

The incidence of isoniazid (INH) resistant Mycobacterium tuberculosis is increasing globally. This study aimed to identify the molecular mechanisms behind the development of INH resistance in M. tuberculosis strains collected from the same patients during the standard course of treatment. Three M. tuberculosis strains were collected from a patient before and during antituberculosis (anti-TB) therapy. The strains were characterized using phenotypic drug susceptibility tests, Mycobacterial Interspersed Repeated Unit-Variable-Number Tandem Repeats (MIRU-VNTR), and whole-genome sequencing (WGS) to identify mutations associated with INH resistance. To validate the role of the novel mutations in INH resistance, the mutated katG genes were electroporated into a KatG-deleted M. tuberculosis strain (GA03). Three-dimensional structures of mutated KatG were modeled to predict their impact on INH binding. The pre-treatment strain was susceptible to INH. However, two INH-resistant strains were isolated from the patient after anti-TB therapy. MIRU-VNTR and WGS revealed that the three strains were clonally identical. A missense mutation (P232L) and a nonsense mutation (Q461Stop) were identified in the katG of the two post-treatment strains, respectively. Transformation experiments showed that katG of the pre-treatment strain restored INH susceptibility in GA03, whereas the mutated katG genes from the post-treatment strains rendered negative catalase activity and INH resistance. The protein model indicated that P232L reduced INH-KatG binding affinity while Q461Stop truncated gene transcription. Our results showed that the two katG mutations, P232L and Q461Stop, accounted for the co-emergence of INH-resistant clones during anti-TB therapy. The inclusion of these mutations in the design of molecular assays could increase the diagnostic performance.IMPORTANCEThe evolution of drug-resistant strains of Mycobacterium tuberculosis within the lung lesions of a patient has a detrimental impact on treatment outcomes. This is particularly concerning for isoniazid (INH), which is the most potent first-line antimycobacterial drug. However, the precise genetic factors responsible for drug resistance in patients have not been fully elucidated, with approximately 15% of INH-resistant strains harboring unknown genetic factors. This raises concerns about the emergence of drug-resistant clones within patients, further contributing to the global epidemic of resistance. In this study, we revealed the presence of two novel katG mutations, which emerged independently due to the stress exerted by antituberculosis (anti-TB) treatment on a parental strain. Importantly, we experimentally demonstrated the functional significance of both mutations in conferring resistance to INH. Overall, this research sheds light on the genetic mechanisms underlying the evolution of INH resistance within patients and provides valuable insights for improving diagnostic performance by targeting specific mutations.

Genetic diversity of Mycobacterium tuberculosis strains isolated from spiritual holy water site attendees in Northwest Ethiopia. A cross-sectional study

BackgroundThe genetic diversity of Mycobacterium tuberculosis complex (MTBC) strains was characterized among isolates from individuals with pulmonary tuberculosis (PTB) symptoms attended holy water sites (HWSs) in the Amhara region, Ethiopia. MethodsA cross-sectional study was done from June 2019 to March 2020 to describe the genetic diversity and drug-resistance profiles of MTBC isolates. Sputum specimens were collected and cultured in the Löwenstein-Jensen culture medium. Line Probe Assay, MTBDRplus VER 2.0, and MTBDRsl VER 2.0 were used to detect first-and second-line anti-TB drug-resistance patterns. A spoligotyping technique was utilized to characterize the genetic diversity. Statistical analysis was performed using STATA 15. ResultsOf 560 PTB-symptomatic participants, 122 (21.8%) were culture-positive cases. Spoligotyping of 116 isolates revealed diverse MTBC sublineages, with four major lineages: Euro-American (EA) (Lineage 4), East-African-Indian (EAI) (Lineage 3), Ethiopian (ETH) (Lineage 7), East Asian (EA) (Lineage 2). The majority (96.6%) of the isolates were EA (lineage 4) and EAI, with proportions of 54.3% and 42.2%, respectively. A total of 31 spoligotype patterns were identified, 26 of which were documented in the SITVIT2 database. Of these, there were 15 unique spoligotypes, while eleven were grouped with 2-17 isolates. SIT149/T3-ETH (n = 17), SIT26/CAS1-DELHI (n = 16), SIT25/CAS1-DELHI (n = 12), and SIT52/T2 (n = 11) spoligotypes were predominant. A rare spoligotype pattern: SIT41/Turkey and SIT1/Beijing, has also been identified in North Shewa. The overall clustering rate of sub-lineages with known SIT was 76.4%.Of the 122 culture-positive isolates tested, 16.4% were resistant to rifampicin (RIF) and/or isoniazid (INH). Multidrug-resistant TB (MDR-TB) was detected in 12.3% of isolates, five of which were fluoroquinolones (FLQs) resistant. SIT149/T3-ETH and SIT21/CAS1-KILI sublineages showed a higher proportion of drug resistance. ConclusionsDiverse MTBC spoligotypes were identified, with the T and CAS families and EA (lineage 4) predominating. A high prevalence of drug-resistant TB, with SIT149/T3-ETH and CAS1-KILI sublineages comprising a greater share, was observed. A study with large sample size and a sequencing method with stronger discriminatory power is warranted to understand better the genetic diversity of circulating MTBC in this cohort of study, which would help to adopt targeted interventions.

Bioorthogonal Metabolic Labeling of the Virulence Factor Phenolic Glycolipid in Mycobacteria.

Surface lipids on pathogenic mycobacteria modulate infection outcomes by regulating host immune responses. Phenolic glycolipid (PGL) is a host-modulating surface lipid that varies among clinical Mycobacterium tuberculosis strains. PGL is also found in Mycobacterium marinum, where it promotes infection of zebrafish through effects on the innate immune system. Given the important role this lipid plays in the host-pathogen relationship, tools for profiling its abundance, spatial distribution, and dynamics are needed. Here, we report a strategy for imaging PGL in live mycobacteria using bioorthogonal metabolic labeling. We functionalized the PGL precursor p-hydroxybenzoic acid (pHB) with an azide group (3-azido pHB). When fed to mycobacteria, 3-azido pHB was incorporated into the cell surface, which could then be visualized via the bioorthogonal conjugation of a fluorescent probe. We confirmed that 3-azido pHB incorporates into PGL using mass spectrometry methods and demonstrated selectivity for PGL-producing M. marinum and M. tuberculosis strains. Finally, we applied this metabolic labeling strategy to study the dynamics of PGL within the mycobacterial membrane. This new tool enables visualization of PGL that may facilitate studies of mycobacterial pathogenesis.

Assessing the Genetic Diversity of Mycobacterium tuberculosis Strains in Kerala, India: A Comprehensive Study

Assessing the Genetic Diversity of Mycobacterium tuberculosis Strains in Kerala, India: A Comprehensive Study

Discovery of 2,9-diaryl-6-carbamoylpurines as a novel class of antitubercular agents

A series of novel 9-alkyl/aryl-2-aryl-6-carbamoylpurines were synthesized, and their activity against Mycobacterium tuberculosis strain H37Rv was assessed. The SAR analysis on the first set of derivatives, with an alkyl or aryl unit at N-9 and a phenolic unit at C-2, showed that the activity depends on the purine ring substituents at N-9 and C-2. A phenyl group at N-9 combined with a 3-hydroxyphenyl or 4-hydroxyphenyl at C-2 improve the activity. The most active compound of this set has a phenyl group at N-9 and a 4-hydroxyphenyl group at C-2, displaying an IC90 = 1.2 μg/mL and a selectivity index higher than 25.5. This compound served as a Hit to design the second set of derivatives. A phenyl group at N-9 was maintained, and the group at C-2 was diversified. The SAR analysis showed that the aryl unit at C-2 must have an oxygen or nitrogen atom bonded in the para position. A proton, a small alkyl or a substituted aryl group may also be bonded to the oxygen. The compound with the 4-methoxyphenyl group at C-2, 1Bd, exhibits the highest activity with an IC90 < 0.19 μg/mL. This compound is highly potent against M. tuberculosis strain H37Rv and non-toxic for VERO mammalian cells with an SI > 153.8. Compound 1Bd was also non-cytotoxic against primary macrophage cultures at IC90, 2xIC90, and 10xIC90 and significantly reduced the bacterial load in M. tuberculosis-infected macrophages at the same concentrations. Compound 1Bd showed a favorable pharmacokinetic profile when administered orally, with major lung and liver accumulation. In vivo antimycobacterial efficacy of 1Bd was tested at 25 mg/kg. At the tested regimen, a decrease in bacterial burden was observed in the liver. Optimization of the treatment regimen should be performed to fully potentiate the in vivo efficacy of our lead molecule, particularly in the lung, the main target organ of M. tuberculosis.

Review for QSAR studies and drug design of selected heterocyclic nucleus of antitubercular drugs

This review article explores the pressing issue of drug-resistant strains of Mycobacterium tuberculosis, which have emerged due to the widespread and uncontrolled use of antibiotics in clinical settings over several decades. In response to this challenge, various methods have been developed for synthesizing new antitubercular compounds. Among these, the fragment-based drug discovery (FBDD) approach has shown promise as an effective strategy. One class of compounds that has exhibited significant potential in combating tuberculosis is 1,2-diazoles. The article discusses the importance of these compounds and their potential as future antitubercular drugs. Additionally, it delves into the various strategies employed in drug development, emphasizing the relevance and efficacy of FBDD. Analytical methods play a crucial role in characterizing antitubercular antibiotics, and the article highlights liquid chromatography and voltammetry as preferred techniques for determining these compounds. The redox (oxidation/reduction) properties of antituberculars make them amenable to analysis using electrochemical methods, with voltammetry being particularly suitable. Furthermore, the article underscores the significance of utilizing voltammetry for quantifying different categories of antibiotics in both dosage forms and human body fluids. The affordability of this method makes it particularly advantageous for developing countries, providing a cost-effective approach to monitor and assess the presence of antitubercular drugs. Overall, the review article offers valuable insights into the current strategies for addressing drug resistance in tuberculosis and highlights the potential of 1,2-diazoles as future antitubercular agents.

Mesenchymal stem cells-derived extracellular vesicles for therapeutics of renal tuberculosis

Extrapulmonary tuberculosis with a renal involvement can be a manifestation of a disseminated infection that requires therapeutic intervention, particularly with a decrease in efficacy of conventional regimens. In the present study, we investigated the therapeutic potency of mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) in the complex anti-tuberculosis treatment (ATT). A rabbit model of renal tuberculosis (rTB) was constructed by injecting of the standard strain Mycobacterium tuberculosis H37Rv into the cortical layer of the kidney parenchyma. Isolated rabbit MSC-EVs were intravenously administered once as an addition to standard ATT (isoniazid, pyrazinamide, and ethambutol). The therapeutic efficacy was assessed by analyzing changes of blood biochemical biomarkers and levels of anti- and pro-inflammatory cytokines as well as by renal computed tomography with subsequent histological and morphometric examination. The therapeutic effect of therapy with MSC-EVs was shown by ELISA method that confirmed a statistically significant increase of the anti-inflammatory and decrease of pro-inflammatory cytokines as compared to conventional treatment. In addition, there is a positive trend in increase of ALP level, animal weigh, and normalization of ADA activity that can indicate an improvement of kidney state. A significant reduction of the area of specific and interstitial inflammation indicated positive affect of MSC-EVs that suggests a shorter duration of ATT. The number of MSC-EVs proteins (as identified by mass-spectometry analysis) with anti-microbial, anti-inflammatory and immunoregulatory functions reduced the level of the inflammatory response and the severity of kidney damage (further proved by morphometric analysis). In conclusion, MSC-EVs can be a promising tool for the complex treatment of various infectious diseases, in particularly rTB.

Model-based impact evaluation of new tuberculosis vaccines in aging populations under different modeling scenarios: the case of China.

The slow descent in TB burden, the COVID-19 pandemic, along with the rise of multidrug-resistant strains of Mycobacterium tuberculosis, seriously threaten TB control and the goals of the End TB strategy. To fight back, several vaccine candidates are under development, with some of them undergoing the phases 2B and 3 of the development pipeline. The impact of these vaccines on the general population needs to be addressed using disease-transmission models, and, in a country like China, which last year ranked third in number of cases worldwide, and where the population is aging at a fast pace, the impact of TB vaccination campaigns may depend heavily upon the age of targeted populations, the mechanistic descriptions of the TB vaccines and the coupling between TB dynamics and demographic evolution. In this work, we studied the potential impact of a new TB vaccine in China targeting adolescents (15-19 y.o.) or older adults (60-64 y.o.), according to varying vaccine descriptions that represent reasonable mechanisms of action leading to prevention of disease, or prevention of recurrence, each of them targetting specific routes to TB disease. To measure the influence of the description of the coupling between transmission dynamics and aging in TB transmission models, we explored two different approaches to compute the evolution of the contact matrices, which relate to the spreading among different age strata. Our findings highlight the dependence of model-based impact estimates on vaccine profiles and the chosen modeling approach for describing the evolution of contact matrices. Our results also show, in line with previous modeling works, that older adult vaccination is a suitable option in China to reduce the incidence of TB as long as the vaccine is able to protect already exposed individuals. This study underscores the importance of considering vaccine characteristics and demographic dynamics in shaping TB control strategies. In this sense, older adult vaccination emerges as a promising avenue for mitigating TB transmission in China but also remarks the need for tailored intervention strategies aligned with demographic trends.

Detection of a historic reservoir of bedaquiline/clofazimine resistance-associated variants in Mycobacterium tuberculosis

BackgroundDrug resistance in tuberculosis (TB) poses a major ongoing challenge to public health. The recent inclusion of bedaquiline into TB drug regimens has improved treatment outcomes, but this advance is threatened by the emergence of strains of Mycobacterium tuberculosis (Mtb) resistant to bedaquiline. Clinical bedaquiline resistance is most frequently conferred by off-target resistance-associated variants (RAVs) in the mmpR5 gene (Rv0678), the regulator of an efflux pump, which can also confer cross-resistance to clofazimine, another TB drug.MethodsWe compiled a dataset of 3682 Mtb genomes, including 180 carrying variants in mmpR5, and its immediate background (i.e. mmpR5 promoter and adjacent mmpL5 gene), that have been associated to borderline (henceforth intermediate) or confirmed resistance to bedaquiline. We characterised the occurrence of all nonsynonymous mutations in mmpR5 in this dataset and estimated, using time-resolved phylogenetic methods, the age of their emergence.ResultsWe identified eight cases where RAVs were present in the genomes of strains collected prior to the use of bedaquiline in TB treatment regimes. Phylogenetic reconstruction points to multiple emergence events and circulation of RAVs in mmpR5, some estimated to predate the introduction of bedaquiline. However, epistatic interactions can complicate bedaquiline drug-susceptibility prediction from genetic sequence data. Indeed, in one clade, Ile67fs (a RAV when considered in isolation) was estimated to have emerged prior to the antibiotic era, together with a resistance reverting mmpL5 mutation.ConclusionsThe presence of a pre-existing reservoir of Mtb strains carrying bedaquiline RAVs prior to its clinical use augments the need for rapid drug susceptibility testing and individualised regimen selection to safeguard the use of bedaquiline in TB care and control.

Whole Genome Sequence Dataset of Mycobacterium tuberculosis Strains from Patients of Campania Region

Tuberculosis (TB) is one of the deadliest infectious disorders in the world. To effectively TB manage, an essential step is to gain insight into the lineage of Mycobacterium tuberculosis (MTB) and the distribution of drug resistance. Although the Campania region is declared a cluster area for the infection, to contribute to the effort to understand TB evolution and transmission, still poorly known, we have generated a dataset of 159 genomes of MTB strains, from Campania region collected during 2018–2021, obtained from the analysis of whole genome sequence. The results show that the most frequent MTB lineage is the 4 according for 129 strains (81.11%). Regarding drug resistance, 139 strains (87.4%) were classified as multi susceptible, while the remaining 20 (12.58%) showed drug resistance. Among the drug-resistance strains, 8 were isoniazid-resistant MTB, 4 multidrug-resistant MTB, while only one was classified as pre-extensively drug-resistant MTB. This dataset expands the existing available knowledge on drug resistance and evolution of MTB, contributing to further TB-related genomics studies to improve the management of this disease.

Transmission dynamics of drug-resistant tuberculosis in Ningbo, China: an epidemiological and genomic analysis.

Tuberculosis (TB), particularly drug-resistant TB (DR-TB), remains a significant public health concern in Ningbo, China. Understanding its molecular epidemiology and spatial distribution is paramount for effective control. From December 24, 2020, to March 12, 2023, we collected clinical Mycobacterium tuberculosis (MTB) strains in Ningbo, with whole-genome sequencing performed on 130 MTB strains. We analyzed DR-related gene mutations, conducted phylogenetic and phylodynamic analyses, identified recent transmission clusters, and assessed spatial distribution. Among 130 DR-TB cases, 41% were MDR-TB, 36% pre-XDR-TB, 19% RR-TB, and 3% HR-TB. The phylogenetic tree showed that 90% of strains were Lineage 2 (Beijing genotype), while remaining 10% were Lineage 4 (Euro-American genotype). The spatial analysis identified hotspots of DR-TB in Ningbo's northern region, particularly in traditional urban centers. 31 (24%) of the DR-TB cases were grouped into 7 recent transmission clusters with a large outbreak cluster containing 15 pre-XDR-TB patients. Epidemiological analyses suggested a higher risk of recent DR-TB transmission among young adult patients who frequently visited Internet cafes, game rooms, and factories. Our study provides comprehensive insights into the epidemiology and genetics of DR-TB in Ningbo. The presence of genomic clusters highlights recent transmission events, indicating the need for targeted interventions. These findings are vital for informing TB control strategies in Ningbo and similar settings.

Comparative analysis of genomic characteristics and immune response between Mycobacterium tuberculosis strains cultured continuously for 25 years and H37Rv.

Tuberculosis (TB) continues to pose a significant global health challenge, emphasizing the critical need for effective preventive measures. Although many studies have tried to develop new attenuated vaccines, there is no effective TB vaccine. In this study, we report a novel attenuated Mycobacterium tuberculosis (M. tb) strain, CHVAC-25, cultured continuously for 25 years in the laboratory. CHVAC-25 exhibited significantly reduced virulence compared to both the virulent H37Rv strain in C57BL/6J and severe combined immunodeficiency disease mice. The comparative genomic analysis identified 93 potential absent genomic segments and 65 single nucleotide polymorphic sites across 47 coding genes. Notably, the deletion mutation of ppsC (Rv2933) involved in phthiocerol dimycocerosate synthesis likely contributes to CHVAC-25 virulence attenuation. Furthermore, the comparative analysis of immune responses between H37Rv- and CHVAC-25-infected macrophages showed that CHVAC-25 triggered a robust upregulation of 173 genes, particularly cytokines crucial for combating M. tb infection. Additionally, the survival of CHVAC-25 was significantly reduced compared to H37Rv in macrophages. These findings reiterate the possibility of obtaining attenuated M. tb strains through prolonged laboratory cultivation, echoing the initial conception of H37Ra nearly a century ago. Additionally, the similarity of CHVAC-25 to genotypes associated with attenuated M. tb vaccine positions it as a promising candidate for TB vaccine development.

PCR Development for Analysis of Some Type II Toxin-Antitoxin Systems, relJK, mazEF3, and vapBC3 Genes, in Mycobacterium tuberculosis and Mycobacterium bovis.

Toxin-Antitoxin (TA) systems are some small genetic modules in bacteria that play significant roles in resistance and tolerance development to antibiotics. Whole genome sequencing (WGS) is an effective method to analyze TA systems in pathogenic Mycobacteria. However, this study aimed to use a simple and inexpensive PCR-Sequencing approach to investigate the type II TA system. Using data from the WGS of Mycobacterium tuberculosis (M. tuberculosis) strain H37Rv and Mycobacterium bovis (M. bovis) strain BCG, primers specific to the relJK, mazEF3, and vapBC3 gene families were designed by Primer3 software. Following that, a total of 90 isolates were examined using the newly developed PCR assay, consisting of 64M. tuberculosis and 26M. bovis isolates, encompassing both 45 rifampin-sensitive and 45 rifampin-resistant strains. Finally, 28 isolates (including 14 rifampin-resistant isolates) were sent for sequencing, and their sequences were aligned and compared to the mentioned reference sequences. The amplicons size of mazEF3, relJK, and vapBC3 genes were 825, 875, and 934 bp, respectively. Furthermore, all tested isolates showed the specific amplicons for these TA families. To evaluate the specificity of the primers, PCR was performed on S. aureus and E.coli isolates. None of the examined samples had the desired amplicons. Therefore, the primers had acceptable specificity. The results indicated that the developed PCR-Sequencing approach can be used to effectively investigate certain types of TA systems. Considering high costs of WGS and difficulty in interpreting its results, such a simple and inexpensive method is beneficial in the evaluation of TA systems in Mycobacteria.

Temperature-Induced Restructuring of Mycolic Acid Bilayers Modeling the Mycobacterium tuberculosis Outer Membrane: A Molecular Dynamics Study.

The emergence of new drug-resistant strains of the tuberculosis pathogen Mycobacterium tuberculosis (Mtb) is a new challenge for modern medicine. Its resistance capacity is closely related to the properties of the outer membrane of the Mtb cell wall, which is a bilayer membrane formed by mycolic acids (MAs) and their derivatives. To date, the molecular mechanisms of the response of the Mtb outer membrane to external factors and, in particular, elevated temperatures have not been sufficiently studied. In this work, we consider the temperature-induced changes in the structure, ordering, and molecular mobility of bilayer MA membranes of various chemical and conformational compositions. Using all-atom long-term molecular dynamics simulations of various MA membranes, we report the kinetic parameters of temperature-dependent changes in the MA self-diffusion coefficients and conformational compositions, including the apparent activation energies of these processes, as well as the characteristic times of ordering changes and the features of phase transitions occurring over a wide range of elevated temperatures. Understanding these effects could be useful for the prevention of drug resistance and the development of membrane-targeting pharmaceuticals, as well as in the design of membrane-based materials.

The Recent Transmission and Associated Risk Factor of Mycobacterium tuberculosis in Golmud City, China.

Tuberculosis (TB) remains a severe public health problem globally, and it is essential to comprehend the transmission pattern to control tuberculosis. Herein, we evaluated the drug-resistant characteristics, recent transmission, and associated risk factors of TB in Golmud, Qinghai, China. In this study, we performed a population-based study of patients diagnosed with TB in Golmud from 2013 to 2018. Drug-susceptibility testing and whole-genome sequencing were performed on 133 Mycobacterium tuberculosis strains. The genomic clustering rate was calculated to evaluate the level of recent transmission. Risk factors were identified by logistic regression analysis. Our results showed that 46.97% (62/132) of strains were phylogenetically clustered and formed into 23 transmission clusters, suggesting a high recent transmission of TB in the area. 12.78% (17/133) strains were multidrug-resistant/rifampicin tuberculosis (MDR/RR-TB), with a high drug-resistant burden. Based on drug resistance gene analysis, we found 23 strains belonging to genotype MDR/RR-TB, where some strains may have borderline mutations. Among these strains, 65.2% (15/23) were found within putative transmission clusters. Additionally, risk factor analysis showed that recent transmission of TB happened more in patients with Tibetan nationality or older age. Overall our study indicates that the recent transmissions of MTB strains, especially genotypic MDR/RR strains, drive the tuberculosis epidemic in Golmud, which could contribute to developing effective TB prevention and control strategies.

Mutation Characteristics of inhA and katG Genes in Isoniazid-Resistant Mycobacterium Tuberculosis Patients in Xinjiang

Objective: To analyze the mutation characteristics of inhA and katG genes in isoniazid-resistant Mycobacterium tuberculosis in Xinjiang. Methods: The katG and inhA in 148 strains of isoniazid-resistant Mycobacterium tuberculosis were amplified through fluorescence quantitative PCR, and the amplified products were sequenced and compared. Results:The inhA gene mutation rate of 148 strains of isoniazid-resistant mycobacterium tuberculosis was 13.51% (20/148), among which the inhA gene mutation rate among patients of Han, Uygur, and Kazakh ethnicity were 15.87%, 13.21%, and 17.65%, respectively. There was no significant difference in the inhA mutation rate among nationalities (c2 = 2.897, P &gt; 0.05). The mutation rate of the katG gene was 84.46% (125/148), among which the mutation rates of patients of Han, Uyghur, and Kazak ethnicities were 82.54%, 84.91%, and 76.47%, respectively. The Hui and other ethnic groups were all affected by the katG gene mutation. There was no significant difference in the mutation rate of the katG gene among different ethnicities (c2 = 3.772, P &gt; 0.05). The mutation rates of the inhA gene in southern Xinjiang, northern Xinjiang, and other provinces were 18.60%, 9.28%, and 37.50%, respectively. The mutation rates of the inhA gene in different regions were statistically different (c2 = 6.381, P &lt; 0.05). There was no significant difference in the inhA mutation rate between patients from southern and northern Xinjiang (c2 = 2.214, P &gt; 0.05) and between southern Xinjiang and other provinces (c2 =1.424, P &gt; 0.05). However, the mutation rate of the inhA gene in patients from other provinces was higher than that in northern Xinjiang (c2 = 5.539, P &lt; 0.05). The mutation rates of the katG gene in southern Xinjiang, northern Xinjiang, and other provinces were 81.40%, 87.63%, and 62.50%, respectively. There was no significant difference in the mutation rates of the katG gene among different regions (c2 = 3.989, P &gt; 0.05). Conclusion: katG gene mutation was predominant in isoniazid-resistant tuberculosis patients in Xinjiang Uygur Autonomous Region, and inhA and katG gene mutation were no different among different ethnic groups.

Design of Cyclobut-3-Ene-1,2 Dione Derivatives as Anti-tubercular Agents

Introduction: Recent studies have shown modified cyclobutene derivatives as potent anti- tubercular agents, and the discovery of drugs against strains of Mycobacterium tuberculosis is still a crucial challenge in the modern world. Objective: The objective of the present study is to design and perform molecular docking studies and in-silico analysis of some novel cyclobut-3-ene-1,2 Dione derivatives with the aim of creating new, potential Mtb ATP synthase inhibitors. Materials and Methods: The structures of 24 compounds of diamino-substituted cyclobut-3-ene-1,2 Dione derivatives against Mtb ATP synthase were drawn using ChemSketch. Further, molecular docking and in-silico studies for the prediction of drug-likeness and pharmacokinetic parameters were carried out. Results: The docking studies of the novel compounds were done, and they had a better docking score with a good binding affinity towards the protein molecule. The synthesized compounds also comply with the in-silico prediction of drug-likeness and pharmacokinetic parameters and have shown good activity against Mtb ATP synthase. Conclusion: The current study shows that the cyclobut-3-ene-1,2 Dione derivatives can serve as a better lead molecule against Mtb ATP synthase and can be involved in further drug discovery

Synthesis of some chalcones derivatives series and their antituberculosis activity

Abstract Chalcone is an important biosynthetic precursor, due to the diverse pharmacological activities. The aim of this current study was to synthesize 14 new chalcone derivatives compounds by incorporating p-alkoxyacetophenones with substituted benzaldehydes. Two new series of chalcone derivatives have been synthesized using the alkylation and the base catalysed Claisen-Schmidt condensation. All the synthesized compounds were fully characterized by IR, 1D NMR (1H and 13C NMR) and 2D NMR (COSY, HMQC, HMBC) as well as mass spectrometry analysis. All the synthesized compounds were assayed in vitro for their antituberculosis activities against Mycobacterium tuberculosis strain. Among them, compounds (E)-1-[4-(heptoxy)phenyl]-3-(2-hydroxy-5-bromophenyl)prop-2-en-1-one (5a), (E)-1-[4-(octyloxy)phenyl]-3-(2-hydroxy-5-bromophenyl)prop-2-en-1-one (5b) and (E)-1-[4-(decyloxy)phenyl]-3-(2-hydroxy-5-bromophenyl)prop-2-en-1-one (5d) showed good activities with the lowest MIC value of 12.5 μg/mL.