## 3 Mycobacteriumophages--General Characteristics and Overview
These engineered additions enable phages to not only enhance the intracellular killing of _M. tuberculosis_--which predominantly resides within macrophages--but to also serve as innovative diagnostic tools through fluorescence or reporter-based detection [63; 64; 65]. Delivery of these engineered phages into infected tissues remains a critical bottleneck, but nanoparticle encapsulation or liposomal formulations have shown promise in facilitating phage entry into macrophages, thereby overcoming one of the major biological barriers in TB therapy [65]. A cornerstone of modern mycobacteriophage research is the SEA-PHAGES program (Science Education Alliance-Phage Hunters Advancing Genomics and Evolutionary Science). This initiative has led to the discovery, isolation, and genome sequencing of thousands of mycobacteriophages by undergraduate researchers worldwide [66]. The sequenced phages--many of which are archived in public databases such as PhagesDB.org--serve as a critical resource for therapeutic development [58]. Not only does this collection enable the identification of candidate phages with lytic activity against mycobacterial pathogens, but it also provides valuable insights into phage evolution, comparative genomics, host-range specificity, and resistance mechanisms [67; 68]. The SEA-PHAGES dataset, by virtue of its scale and diversity, forms the taxonomic and functional foundation of the mycobacteriophage field. It offers a unique platform for understanding genomic mosaicism, exploring gene content relationships among phage clusters, and designing recombinant phages tailored to specific clinical applications. In particular, phage selection and genetic modification strategies are increasingly informed by comparative analyses within this database, allowing for the rational design of phage cocktails and engineered variants suitable for therapeutic deployment. Despite significant scientific progress, several challenges still hinder the widespread adoption of mycobacteriophage therapy for tuberculosis. Foremost among these is the difficulty of effectively delivering phages to intracellular _M. tuberculosis_ residing within human tissues, particularly within granulomatous lesions. Furthermore, phages are susceptible to immune system clearance, which may reduce their bioavailability after systemic administration [69]. Regulatory hurdles, including the standardization of production, quality control, and clinical trial design, also remain substantial barriers to clinical translation. Nevertheless, the successful use of engineered phages in compassionate treatment cases--for example, in patients with disseminated _M. abscessus_ infections--demonstrates that personalized phage therapy is feasible and potentially translatable to _M. tuberculosis_, especially in multidrug-resistant or refractory cases [61; 70]. Having characterized the structural and biological diversity of mycobacteriophages, the discussion now turns to their translational potential. The following sections examine their emerging roles in diagnostics and therapy, the technological advances driving phage-based applications, and the key challenges and future perspectives shaping the field.