01
Transmission
T4 does not spread between people or cause human infection. Free phage particles encounter susceptible E. coli, attach to the bacterial surface, and inject their DNA into the cell.
Detailed lesson · DNA Virus
Bacteriophage T4
Bacteriophage T4
A bacteriophage that infects and replicates inside E. coli bacteria.
FamilyStraboviridaeGenomeLinear double-stranded DNA
01
T4 follows a lytic life cycle rather than remaining dormant in the host chromosome.
02
A single infected bacterium can release many newly assembled phage particles.
03
Research on T4 contributed to understanding how genes control protein production.
01 · Specimen
Explore the virion
Rotate the specimen, inspect its form, and shift into X-Ray mode.
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02 · Context
Overview
Bacteriophage T4 is a virus that infects the bacterium Escherichia coli. It is one of the best-studied bacteriophages and has helped scientists uncover fundamental principles of genes, DNA replication, and virus assembly.
03 · Taxonomy
Classification
T4 belongs to the family Straboviridae, genus Tequatrovirus, within the tailed bacterial viruses. It is part of the historically named T-even group, which also includes phages T2 and T6.
- Family
- Straboviridae
- Genome
- Linear double-stranded DNA
- Host
- Escherichia coli and closely related bacteria
- Size
- About 200 nm long
- Discovery
- Classified among the T-even bacteriophages in the 1940s
- Transmission
- Contact between free phage particles and susceptible bacterial cells
04 · Anatomy
Structure
The physical architecture and genetic material of the pathogen.
T4 has an elongated icosahedral head containing its DNA, a contractile tail, a baseplate, and long tail fibers. The fibers recognize a suitable bacterium, while contraction of the tail sheath helps deliver the genome across the cell envelope.
05 · Health
Disease information
Clinical presentation, risk reduction, and approaches to care.
02
Symptoms
T4 produces no symptoms in humans, animals, or plants. In a susceptible bacterial culture, infection rapidly redirects cell activity and ends with lysis—the bursting of the bacterial cell.
03
Prevention
No public-health prevention is needed because T4 is not a human pathogen. In laboratories and biotechnology facilities, routine sterile technique and decontamination help prevent unwanted phage contamination of bacterial cultures.
04
Treatment
Treatment is not applicable to people. T4 and related phages are studied as tools for molecular biology and as possible foundations for therapies that target harmful bacteria.
06 · History
Timeline
Defining moments in research, discovery, and public health.
Frederick Twort and Félix d’Hérelle independently describe viruses that kill bacteria.
T4 is classified among a numbered set of phages that infect *E. coli*.
Experiments using T4 help reveal that the genetic code is read in three-letter units.
07 · Curiosities
Interesting facts
T4 resembles a microscopic lunar lander, with a head, tail, baseplate, and leg-like fibers.
Its contractile tail works as a molecular injection apparatus.
The complete particle is self-assembled from many protein components in a carefully controlled sequence.
08 · Further reading
References
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