Varsha Chauhan

We report the genome sequence of a novel species of nontuberculous mycobacterium (NTM) belonging to the Mycobacterium terrae complex (MTC). The strain SVM_VP21 was isolated from the mouthwash sample of a healthy human adult residing in Delhi, India. The strain exhibited smooth, cream-coloured colonies on Lowenstein Jensen (LJ) medium after 2 weeks of incubation and could not be identified by Hain’s Genotype Mycobacterium CM/AS line probe assay. Whole genome sequencing (WGS) of SVM_VP21 was performed using Illumina NovaSeq 6000 platform for final identification. The whole genome sequence was assembled using Shovill. Gene annotation was performed by Rapid Annotation using Subsystem Technology (RAST) and Prokaryotic Genome Annotation Pipeline (PGAP). The genome of 4,882,418 bp exhibited 67.3% GC content, 59 contigs, 4557 genes and 4502 coding sequences. The genome also encoded four rRNAs, 48 tRNAs, three non-coding RNAs and 177 pseudo genes. BLASTn analysis of the 16S rRNA and hsp65 gene sequences retrieved by WGS showed 100% and 95% identity to M. heraklionense, respectively. AutoMLST showed 93.5% average nucleotide identity of SVM_VP21 to M. virginiense. Digital DNA-DNA Hybridization, finally, identified SVM_VP21 as a novel species of the M. terrae complex. The name Mycobacterium cavoris sp. nov. is proposed for the strain in reference to its isolation from the oral cavity. The data presented here would help in understanding the novel species, which though obtained from a healthy individual in this study, may be a potential pathogen.

In pursuit of potential chemotherapeutic alternates to combat severe tuberculosis infections, novel heterocyclic templates derived from clinically approved anti‐TB drug isoniazid and isatin have been synthesized that demonstrate potent inhibitory action against Mycobacterium tuberculosis, and compound 4i with nitrophenyl motif exhibited the highest anti‐TB efficacy with a MIC value of 2.54 μM/ml. Notably, the same nitro analog 4i shows the best antioxidant efficacy among all the synthesized compounds with an IC₅₀ value of 37.37 μg/ml, suggesting a synergistic influence of antioxidant proficiency on the anti‐TB action. The titled compounds exhibit explicit binding affinity with the InhA receptor. The befitting biochemical reactivity and near‐appropriate pharmacokinetic proficiency of the isoniazid conjugates is reflected in the density functional theory (DFT) studies and ADMET screening. The remarkable anti‐TB action of the isoniazid cognates with marked radical quenching ability may serve as a base for developing multi‐target medications to confront drug‐resistant TB pathogens.

Aim: Developing potent medicinal alternates for tuberculosis (TB) is highly desirable due to the advent of drug-resistant lethal TB strains. Methods & results: Novel indole-isoniazid integrates have been synthesized with promising antimycobacterial action against the H37Rv strain, and the nitro analogs 4e and 4j show the highest efficacy with a minimum inhibitory concentration of 1.25 μg/ml. The molecular docking studies against InhA support the experimental findings. Indole conjugates display remarkable radical quenching efficiency, and compounds 4e and 4j demonstrate maximum IC₅₀ values of 50.19 and 52.45 μg/ml, respectively. Pharmacokinetic analysis anticipated appreciable druggability for the title compounds. Conclusion: The notable bioaction of the indole-isoniazid templates projects them as potential lead in developing anti-TB medications with synergetic antioxidant action.

Mammalian cell entry (mce) operons play a vital role in cell invasion and survival of M. tuberculosis. Of the mce genes, the function of Rv0590A is still unknown. The present study was performed to investigate the function and immunogenic properties of the protein Rv0590A. Human leukemia monocytic cell line (THP-1) derived macrophages were infected with M. tuberculosis H37Rv at 3, 6, and 24 h of infection. The maximum colony forming units (CFU) were observed at 6 h (p < 0.005), followed by 3 h after infection. M. tuberculosis H37Rv and clinical isolates representative of Delhi/CAS, EAI, Beijing, Haarlem and Euro-American-superlineage were included in the study for expression analysis of mce1A, mce2A, mce3A, mce4A, and Rv0590A genes. Maximum upregulation of all mce genes was observed at 3 h of infection. All the five clinical isolates and H37Rv upregulated Rv0590A at various time points. Macrophage infection with M. tuberculosis H37Rv-overexpressing Rv0590A gene showed higher intracellular CFU as compared to that of wild-type H37Rv. Further, purified Rv0590A protein stimulated the production of TNFα, IFNγ, and IL-10 in macrophages. Thus, Rv0590A was found to be involved in cell invasion and showed good immunological response.

The emergence of drug-resistant tuberculosis is a significant global health issue. The presence of heteroresistant Mycobacterium tuberculosis is critical to developing fully drug-resistant tuberculosis cases. The currently available molecular techniques may detect one copy of mutant bacterial genomic DNA in the presence of about 1–1000 copies of wild-type M. tuberculosis DNA. To improve the limit of heteroresistance detection, we developed SuperSelective primer-based real-time PCR assays, which, by their unique assay design, enable selective and exponential amplification of selected point mutations in the presence of abundant wild-type DNA. We designed SuperSelective primers to detect genetic mutations associated with M. tuberculosis resistance to the anti-tuberculosis drugs isoniazid and rifampin. We evaluated the efficiency of our assay in detecting heteroresistant M. tuberculosis strains using genomic DNA isolated from laboratory strains and clinical isolates from the sputum of tuberculosis patients. Results show that our assays detected heteroresistant mutations with a specificity of 100% in a background of up to 10⁴ copies of wild-type M. tuberculosis genomic DNA, corresponding to a detection limit of 0.01%. Therefore, the SuperSelective primer-based RT-PCR assay is an ultrasensitive tool that can efficiently diagnose heteroresistant tuberculosis in clinical specimens and contributes to understanding the drug resistance mechanisms. This approach can improve the management of antimicrobial resistance in tuberculosis and other infectious diseases.