The infection of Escherichia coli by T2 and T4 bacteriophages as seen in the electron microscope I. Attachment and penetration

Abstract

The infection of Escherichia coli by T2 and T4 bacteriophages has been studied with the electron microscope using both thin-sectioning and negative-staining techniques. The initial attachment of T2 and T4 viruses to the bacterial surface is made by the distal ends of the phages' long tail fibers. The second major step in the adsorption process seems to be a repositioning of the bacteriophage so that its short tail pins which were at first more than 1000 A from the bacterial surface are brought into very close proximity to the cell wall. In the final step in the attachment of T2 and T4 bacteriophages the tail sheath contracts and the baseplate is pulled along the needle away from the cell wall. At this stage the tail pins are no longer visible, but short tail fibers about 370 A long connect the baseplate directly to the cell wall, while the long tail fibers are found attached to the wall at points apparently corresponding to their initial sites of attachment. The needle appears to penetrate about 120 A into the cell wall.