The initial steps in infection with coliphage M13

Infection of Escherichia coli with the rod-shaped DNA bacteriophage M13 begins with an irreversible attachment of the phage to one of a very limited number of sites on the cell surface. The attachment rate is maximal in media of molar ionic strength of about 0.1. Temperature influences the rate only to the extent that it affects the rate of phage diffusion. Following attachment, the phage DNA penetrates into the cell, leaving behind over 90% of the protein. The penetration process is extremely temperature sensitive, with an energy of activation of about 25,000 cal, can occur in less than 20 seconds at 37°, and depends on the host cell metabolism. Thus, the initial steps of infection with M13 fir into the general pattern known for other bacteriophages. The penetration is not analogous to the release of M13 phage from infected cells, where intact virus particles pass through the cell wall.