Research Projects

Tuberculosis (TB), caused by the pathogen Mycobacterium tuberculosis (Mtb), continues to be one of the leading causes of infectious disease-related mortality worldwide, accounting for approximately 10 million new cases and over 1.6 million deaths each year. The emergence of drug-resistant Mtb strains threatens TB control efforts (WHO, 2025), compromising the efficacy of frontline antibiotics such as isoniazid, rifampicin, ethambutol, and pyrazinamide (1). Conventional research has primarily focused on genetic mutations affecting drug targets, such as katG, rpoB, inhA, and embB (2). Still, these do not fully account for the complex, multifactorial nature of resistance. Recent studies suggest microbial extracellular vesicles (EVs) play roles in antimicrobial resistance through drug sequestration, efflux regulation, and intercellular signaling (3). Mtb is also known to secrete EVs, yet their contribution to drug resistance remains understudied. Mtb-derived EVs (MEVs) carry a rich repertoire of secretory molecules, including lipoproteins (e.g., LpqH, LprG), lipoglycans (e.g., lipoarabinomannan), virulence proteins (e.g., KatG, SodA, antigen 85 complex), enzymes, and iron-acquisition factors like mycobactin (4-6). Proteome profiling has revealed classical ESX-1 and ESX-5 substrates (EsxA, and PPE41 and EsxN respectively) to be present in EV, suggesting cross-talk between type VII secretion systems and vesicle-mediated export. Beyond classical systems (SecA1, Tat, ESX-1), non-classical pathways like SecA2 also mediate cargo loading, exporting proteins and Mtb RNA into host vesicles that activate innate immunity via RIG-I/MAVS signaling (7). These findings raise the possibility of horizontal gene transfer and immune modulation via EVs. However, the link between such EV-associated cargo and antibiotic resistance, whether via drug efflux, immune evasion, or survival under drug pressure, remains poorly defined. Stress conditions at the host-pathogen interface, such as iron limitation and antibiotic exposure, are known to alter EV production and cargo composition. Under these conditions, differential packaging of secretory proteins and RNAs has been observed, implying adaptive cargo sorting. Despite this, no systematic study has compared the EV profiles of drug-sensitive versus drug-resistant strains. It is plausible that drug-resistant Mtb strains may selectively package distinct secretory proteins that contribute to persistence under therapeutic pressure, either by neutralizing antibiotic stress, modulating efflux systems, or priming host immune pathways to favor bacterial survival. This project aims to characterize the secretory proteome of EVs from drug-sensitive (DS) and drug-resistant (DR) Mtb strains to identify resistance-associated cargo and evaluate MEVs as minimally invasive biomarkers. By dissecting EV composition and secretion dynamics, we seek to uncover novel molecular mediators of TB pathogenesis and persistence.