Relevance of genomic diversity of Mycobacterium tuberculosis complex in Africa

Genome-wide analyses of Mycobacterium tuberculosis complex isolates reveal insights into circulating lineages and drug resistance mutations in The Gambia

Tuberculosis (TB), caused by the Mycobacterium tuberculosis complex (MTBC), remains a pressing global health challenge, with the West African region, including The Gambia, experiencing a substantial burden. This study explores the genetic diversity of MTBC strains circulating in The Gambia for nearly two decades (2002-2021) to enhance understanding of drug resistance dynamics and inform targeted diagnostic and treatment strategies. Using whole-genome sequencing (WGS) data from 1,803 TB isolates, we identified the predominance of lineage 4 (L4, 67.2%) and lineage 6 (L6, 26.6%) strains, with L4 showing more significant genetic variability over time. Drug susceptibility analysis of these isolates revealed that 78% (1421 isolates) were drug-susceptible, while 6.5% (119 isolates) exhibited resistance, primarily to isoniazid, rifampicin, and their combination. Additionally, 15.5% (282 isolates) were classified as Other, having potential drug-resistance mutations of uncertain significance by the WHO catalogue. Interestingly, our resistance-associated analysis showed the lineage 6 specific ethambutol uncertain significance (by WHO catalogue) mutation (embC Ala307Thr) more prevalent in The Gambia than in West Africa and globally. Structural analysis showed that first-line drug resistance mutations frequently occur in solvent-inaccessible and conserved regions of proteins, often impacting protein stability and reflecting a balance between resistance, fitness, and evolutionary adaptation. This study highlights the coexistence of globally prevalent and regionally restricted MTBC lineages, underscoring the importance of region-specific TB control measures. Integrating bioinformatic and structural analyses revealed many uncertain significant mutations by the WHO catalogue in The Gambian isolates compared to West Africa and globally. These findings reinforce the necessity of continuous genomic surveillance to address the evolving challenges of TB in high-burden settings like West Africa.

Mycobacterium tuberculosis complex molecular networks and their regulation: Implications of strain heterogeneity on epigenetic diversity and transcriptome regulation

Tuberculosis has been a public health crisis since the 1900, which has caused the highest mortalities due to a single bacterial infection worldwide, that was recently further complicated by the Coronavirus disease 2019 pandemic. The causative agent of Tuberculosis, Mycobacterium tuberculosis, belongs to a genetically well-characterized family of strains known as the Mycobacterium tuberculosis complex, which has complicated progress made towards eradicating Tuberculosis due to pathogen-specific phenotypic differences in the members of this complex. Mycobacterium tuberculosis complex strains are genetically diverse human- and animal-adapted pathogens belonging to 7 lineages (Indo-Oceanic, East-Asian, East-African Indian, Euro-American, M. africanum West Africa 1, M. africanum West Africa 2 and Ethopia), respectively and the recently identified Lineage 8 and M. africanum Lineage 9. Genomic studies have revealed that Mycobacterium tuberculosis complex members are ∼99 % similar, however, due to selective pressure and adaptation to human host, they are prone to mutations that have resulted in development of drug resistance and phenotypic heterogeneity that impact strain virulence. Furthermore, members of the Mycobacterium tuberculosis complex have preferred geographic locations and possess unique phenotypic characteristics that is linked to their pathogenicity. Due to the recent advances in development next generation sequencing platforms, several studies have revealed epigenetic changes in genomic regions combined with "unique" gene regulatory mechanisms through non-coding RNAs that are responsible for strain-specific behaviour on in vitro and in vivo infection models. The current review provides up to date epigenetic patterns, gene regulation through non-coding RNAs, together with implications of these mechanisms in down-stream proteome and metabolome, which may be responsible for "unique" responses to infection by members of the Mycobacterium tuberculosis complex. Understanding lineage-specific molecular mechanisms during infection may provide novel drug targets and disease control measures towards World Health organization END-TB strategy.

Comprehensive coverage on anti-mycobacterial endeavour reported during 2022

TB being one of the deadliest diseases and second most common infectious cause of deaths, poses the severe threat to global health. The extended duration of therapy owing to resistance and its upsurge in immune-compromised patients have been the driving force for the development of novel of anti-TB scaffolds. Recently, we have compiled the account of anti-mycobacterial scaffolds published during 2015-2020 and updated them in 2021. The present work involves the insights on the anti-mycobacterial scaffolds reported in 2022 with their mechanism of action, structure activity relationships, along with the key perceptions for the design of newer anti-TB agents for the broader interests of medicinal chemists.

Spotlight on mycobacterial lipid exploitation using nanotechnology for diagnosis, vaccines, and treatments

Tuberculosis (TB), historically the most significant cause of human morbidity and mortality, has returned as the top infectious disease worldwide, under circumstances worsened by the COVID-19 pandemic's devastating effects on public health. Although Mycobacterium tuberculosis, the causal agent, has been known of for more than a century, the development of tools to control it has been largely neglected. With the advancement of nanotechnology, the possibility of engineering tools at the nanoscale creates unique opportunities to exploit any molecular type. However, little attention has been paid to one of the major attributes of the pathogen, represented by the atypical coat and its abundant lipids. In this review, an overview of the lipids encountered in M. tuberculosis and interest in exploiting them for the development of TB control tools are presented. Then, the amalgamation of nanotechnology with mycobacterial lipids from both reported and future works are discussed.