Lysis from without (LFW) occurs in two steps: (1) sensitization of cells by phage, which renders the cells susceptible to (2) destruction of an essential cell structure by an extracellular lytic enzyme. Virolysin, from phage-infected cells, was used in these studies. Normal cell autolysin is also effective.
Evidence is presented that:
1. Neither phage nor lysin alone causes LFW.
2. Sensitization requires phage adsorption.
3. It can be caused by non-infectious particles. This establishes a new biological activity of the particle.
4. Heat, U.V., detergents, penicillin, and other damaging agents also sensitize cells.
5. Sensitization involves a non-lethal, reversible reaction.
6. Sensitization by phage prevents virus synthesis. Following adsorption, a cell can undergo sensitization or infection but not simultaneously. When only a few particles are adsorbed, infection can occur; when sufficient particles are adsorbed, sensitization takes place.
7. Quantitative aspects of LFW are described. Lysis proceeds logarithmically. The lysis end-point depends upon the phage concentration but is independent of the enzyme concentration.