We have studied the antimycobacterial efficacy of the liposomal preparation of mycobacteriophage D29 on models of tuberculous granuloma in vitro and in the experiment on laboratory mice of the relatively resistant strain C57BL/6, infected with the virulent strain of M. tuberculosis H37Rv. We have shown the preparation of liposomal preparation of the lytic mycobacteriophages and its characteristics. The experiments showed a significant lytic effect of the liposomal form of mycobacteriophage D29 both on the model of tuberculous granuloma formed by human blood mononuclear cells in vitro, which is formed in the presence of Mycobacterium tuberculosis and on the model of tuberculous infection in C57BL/6 mice. Keywords: mycobacteriophage D29, M. tuberculosis, liposomes, tuberculous granuloma in vitro, tuberculosis infection and its treatment.

Background: The use of liposomal lytic mycobacteriophage D29 has been shown to be an effective and less toxic alternative to traditional antibiotics for treating tuberculosis caused by drug-resistant M. tuberculosis strains. Methods: A previously developed liposomal formulation of mycobacteriophage D29, with a size of 0.45 micrometers, was used. The efficacy of this preparation of lytic mycobacteriophages was studied in a model of tuberculosis infection in C57BL/6 mice caused by the multidrug-resistant M. tuberculosis CAO120/26 (SHRE) strain. The acute and chronic toxicity of this liposomal formulation was also investigated. Results: The results demonstrated a significant antimycobacterial effect of a liposomal mycobacteriophage D29-based drug against tuberculosis infection caused by the drug-resistant pathogen. The number of CFUs of MTB in lung homogenates from untreated infected mice was 326875 ± 149221, whereas in treated mice, it was 307 ± 163. In the study of the acute and chronic toxicity of the drug, no significant signs of toxicity were found. Conclusions: The results of experimental studies on the use of liposomal formulations of lytic mycobacteriophages in animal models suggest that they may have potential to significantly enhance the efficacy of chemotherapy in patients with tuberculosis, including those with drug-resistant strains.

50 scientific publications between 2018 and 2025 were analyzed, focusing on drug delivery systems and benefits of linezolid-loaded nanoparticles. Orally administered anti-tuberculosis drugs do not always achieve sufficient bactericidal concentrations at the site of infection, regardless of their serum levels. Consequently, even with treatment adherence, approximately 1% of patients may develop multidrug-resistant tuberculosis (MDR-TB) due to pharmacokinetic variability. This highlights the need for advanced delivery systems that ensure targeted drug release directly into the affected lung tissue. Nanoformulations of linezolid (e.g., dry powders, aerosols) have been developed. These formulations remain stable for up to 6 months and increase bioavailability to 55.2%, enabling dose reduction. This opens up real prospects for lowering the therapeutic dose of the drug.

Interferon-gamma (IFN-γ) is an important cytokine in host defense against tuberculosis infection. In some cases, administration of IFN-γ during tuberculosis infection can promote faster cure. In the present work, we have shown that in a mouse model, human interferon-gamma, exhibits some anti-tuberculosis activity, especially in combination with isoniazid.

INTRODUCTION. The spread of antibiotic-resistant mycobacteria necessitates new therapeutic approaches for tuberculosis, phage therapy being one of them. Liposomal mycobacteriophages are considered to be a way to enhance their efficacy; however, a comprehensive assessment of their stability is warranted for the further use of such preparations. AIM. This study aimed to evaluate the long-term stability (over six months) of a liposomal form of mycobacteriophage D29 under storage conditions at 4 °C based on a set of physicochemical and functional parameters to substantiate its further preclinical study. MATERIALS AND METHODS. The stability of liposomal form D29 was assessed over six months of storage at 4 °C. Sampling was performed at the following time points: 0; 1.5; 3; 4.5; and 6 months. The degree of phage encapsulation (%) was quantified by real-time polymerase chain reaction (qPCR). The surface charge (zeta potential) was measured by electrophoretic light scattering (Doppler electrophoretic mobility). Liposome morphology was analyzed using transmission electron microscopy. Functional activity was assessed by determining lytic activity via the Grazia titration method on M. smegmatis mc² 155 culture. RESULTS. High stability of the liposomal phage D29 form was demonstrated. Lytic activity remained at a level of ~10 ⁹ PFU/mL throughout the storage period (six months, 4 °C). The degree of encapsulation decreased insignificantly (>88% of the initial value). The constant zeta potential value (from –6.1±0.3 to –8.2±0.5 mV) confirmed colloidal stability of the suspension without particle aggregation throughout the entire storage period. CONCLUSIONS. The liposomal mycobacteriophage D29 demonstrates high physicochemical and functional stability after long-term storage (six months, 4 °C), with preserved lytic activity and a high degree of encapsulation. The findings substantiate the prospects for further preclinical and subsequent clinical trial of this preparation designed to treat mycobacterial infections.

Mycobacteriophages are viruses that selectively infect mycobacteria. Due to their specificity and lytic activity, they are considered a promising tool for controlling mycobacterial infections, especially amid rising antibiotic resistance. Their significant genetic diversity and unique biological properties have generated sustained global research interest, supported by successes in treating complex infections caused by non-tuberculous mycobacteria. However, data on phage populations and applied research results in the Russian Federation remain fragmented, necessitating systematization to assess the genuine potential. This review is based on literature data and the authors’ personal results, summarizing current knowledge on mycobacteriophage biology and analyzing the prospects for their therapeutic and diagnostic application. It examines data on mycobacteriophage taxonomic and genomic diversity in a global context, describes the first characterized Russian isolates, including phages Vic9 and Yasnaya_Polyana, and details a domestic collection of 15 phages. The collection aligns with global trends and includes unique findings, such as the phage Arbat with an anomalously large genome and extremely low similarity to known phages. In the therapy context, the review explores strategies for creating effective therapeutic agents, including the design of phage cocktails and genetic modification to switch them to a lytic state. It presents a critical analysis of international clinical experience using phages in parallel with mycobacterioses and highlights fundamental barriers to phage therapy for tuberculosis. Special attention is paid to domestic delivery systems, particularly liposomal formulations of phage D29, which have demonstrated high efficacy against M. tuberculosis, including multidrug-resistant strains, and a favorable safety profile in preclinical studies. In the diagnostics section, the evolution of phage-based methods is traced — from biological amplification tests to reporter systems — and the Russian-developed test system “TB-Phage-LCh” for phenotypic tuberculosis drug susceptibility testing is presented. Despite regulatory complexities and the need to study immunogenicity, this work demonstrates that Russian Federation possesses a solid scientific foundation for developing this field. Further research focused on in-depth characterization of domestic isolates, optimization of therapeutic platforms, and conducting controlled clinical trials could lead to creating effective phage-based drugs and diagnostic tools capable of holding an important place in the arsenal against drug-resistant mycobacterial infections.