T7 phage

German-American biophysicist Max Delbrück worked with the same virus in the late 1930s, calling it phage δ, and French-Canadian microbiologist Félix d'Herelle likely studied its close relative in the 1920s.

Due to the short latent period, most physiological studies are conducted at 30˚C where infected cells lyse after 30 min.

However, high-fitness strains of T7 have been isolated with a latent period of only ~11 min at 37˚C growing under optimal conditions in rich media results.

In some strains of T7, the tail fibers are replaced with tail-spikes that degrade the O- or K-antigens on the cell surface by way of enzymatic activity.

[5] The adsorption and penetration process use lysozymes to create an opening within the peptidoglycan layer of the bacterial cell wall, allowing transfer of the viral DNA into the bacterium.

[18] T7 bacteriophage has been evolved to override several of the host bacteria's defenses including the peptidoglycan cell wall and the CRISPR system.

[19] Under optimal conditions, the T7 phage can complete the lytic process within 25 minutes, leading to the death of the E. coli host cell.

[21] This repair of double-strand breaks is facilitated by the gene 2.5 protein that promotes the annealing of homologous complementary strands of DNA.

Bacteriophage T7 Structural Model at Atomic Resolution [ 1 ]
Colored microphotography of a T7 virion with its six tail fibers that are folded back against its capsid. The fibers extend as the virus locates a suitable host.
Annotated schematic drawing of a Enterobacteria phage T7 virion (cross section and side view)
T7 infecting a host cell . Schematic drawing with annotations.
Tomograms of a T7 virion in action. T7 is using its fibers to "walk" across the cell surface and finally infect the cell.
Reproduction cycle of T7, in total
Replication machinery of T7, details