mycobacteriophage

Mycobacteriophages are bacteriophages that infect bacteria of the genus Mycobacterium. In laboratory studies, they most commonly infect Mycobacterium smegmatis, a non-pathogenic model species, but some also infect members of the Mycobacterium tuberculosis complex and other pathogenic mycobacteria. They are predominantly dsDNA tailed phages and show diverse morphology, including long contractile tails (myoviruses), flexible noncontractile tails (siphoviruses), and short tails (podoviruses). Many are temperate and capable of lysogeny, while others are strictly lytic.

Genome organization is typical of tailed phages, with modules for structure, DNA replication, regulation, lysis, and, in temperate phages, integrase and repressor genes. Genomes are mosaic and frequently rearranged due to horizontal exchange. Clusters and subclusters are defined by gene content similarity, and thousands of mycobacteriophages have been cataloged in the Actinobacteriophage Database (PhagesDB).

Practical applications include use as genetic tools for mycobacteria, such as integration-proficient vectors derived from temperate phages (for example, L5-family) and transducing phages. Endolysins and other phage-derived enzymes have been explored as potential antimicrobials. Phages are also studied for phage therapy against drug-resistant mycobacterial infections, with several compassionate-use cases and ongoing research, though clinical approval remains limited.

Discovery dates to environmental samples and enrichment with mycobacteria; the field emphasizes host range, infection dynamics, and genome mining to understand phage–host interactions and to expand the toolkit for mycobacterial genetics.