Bacteriophage Infection
Explore T4 infection of E. coli in six interactive steps, from receptor recognition to lysis. Rotate the cutaway to follow DNA into the cell.
How T4 infects a bacterial cell
This interactive teaching model follows T4 infection of E. coli. Select a stage above or read the sequence below; the explanation remains available without WebGL.
Finding a host
T4 encounters a bacterium. Its long tail fibers contact and recognize receptors on the host surface. It cannot infect just any cell.
Attachment and anchoring
After recognition, the phage moves closer to the surface. Its baseplate rearranges and short tail fibers help anchor it firmly before DNA transfer.
DNA transfer
The tail sheath becomes shorter and wider, driving the inner tube downward. DNA then passes along the tail channel into the cytoplasm; the protein capsid stays outside.
Replication and synthesis
Viral DNA replicates inside the host. The host’s ribosomes and other systems use viral genetic instructions to produce proteins for new phages.
Assembly of new phages
New genomes are packaged into heads. Heads, tails and tail fibers assemble to form progeny that can infect another host.
Lysis and release
The lysis system disrupts the cell envelope and the host bursts. Newly formed phages enter the environment and may start another infection cycle.
Model assumptions and sources
- The incoming phage is enlarged and fewer progeny are shown. Views change between stages; sizes are not for measurement.
- Envelope thickness, receptors, DNA helices and protein particles are enlarged.
- Animation progress is a teaching sequence, not the actual duration of infection.
- DNA replication, protein synthesis and assembly partly overlap in a real cell.