Final answer:
The T4 bacteriophage is the viral phage known for infecting E. coli with a complex structure that includes a protein tail for attachment and a head housing DNA, leading to the host cell's destruction.
Step-by-step explanation:
The most intensively studied virulent phage that infects E. coli is the T4 bacteriophage. This phage is known for its complex structure, which includes a protein tail that it uses to latch onto the host cell and a head structure that contains its DNA. As a virulent phage, T4 undergoes the lytic cycle, inevitably leading to the death of the host cell upon infection.