The initial steps in infection with coliphage M13

Filamentous bacterial viruses

“…Another source of this hyperchromicity could be n-,w* transitions in the DNA (53 (87,190,205). Plaque-forming ability is resistant to deoxyribonuclease and ribonuclease and is moderately resistant to Pronase and trypsin; however, it is sensitive to the proteolytic enzymes Nagarse, ficin, subtilisin, and papain (132,135,158,162,168,191).…”

“…8). There are only a few of these pili per bacterium (32,41,128), corresponding to the two to three adsorption sites found for Ff (95,191). The adsorption sites apparently can be used only once, since infected cells cannot be superinfected, although they can be co-infected (85,91,95,190).…”

“…The adsorption sites apparently can be used only once, since infected cells cannot be superinfected, although they can be co-infected (85,91,95,190). The small number of adsorption sites accounts for the observation that the adsorption rate constant is 100-fold lower thanfor T-even phages under similar conditions and also lower than for 4X174 and RNA phage (85,191).…”

“…Adsorption rate increases twofold between 0 and 40 C and then drops off sharply at higher temperatures. Thus, the rate behaves as if it were limited solely by diffusion and has no heat of activation (191).…”

“…Adsorption is irreversible; no conditions have been found under which the virus can be eluted from the cells after adsorption, without breaking off pili. Adsorption is prevented by 0.001 M ZnII (191). F pili are involved not only in adsorption of Ff but also in formation of mating pairs of bacteria and in adsorption of RNA phage.…”