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 vires 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.
SUMMARYThe formation and role of enzyme, virolysin, in StaphyZococcus aureus K, infected with phages P, and PI, are described. Virolysin is a by-product of the metabolism of the cell which is actively producing phage, not of the normal cell. Virolysin is first detected within 10-15 min. in a 40-50min. latent period and increases linearly until lysis. Normal cell autolysin remains constant during infection. Observations on lysis and phage release show that (1) certain inhibitors which prevent lysis of the cocci by external virolysin also prevent lysis and phage release when added at the end of the latent period; (2) the rate of premature lysis of, and phage release from, cocci chilled during the latent period depends upon their virolysin content. Both observations suggest that virolysin functions in phage release.
of brucellae by the combined action of glycine and a lysozyme-like agent from rabbit monocytes. J. Bacteriol. 82:342-353. 1961.-An acidextractable lytic material was obtained from rabbit monocytes. It acts on a substrate in the walls of brucellae and has properties similar to egg-white lysozyme. Brucella melitensis strain Rev Is is completely resistant to this agent and also to crystalline lysozyme, but when the cells are exposed to sufficient amounts of glycine, the surface is rendered susceptible to these lytic agents. Rough type Rev Is cells are more susceptible than smooth, and the virulent B. melitensis strain 6015 is most resistant.
SUMMARYVarious strains of Staphylococcus aureus which type exclusively with phages of lytic group I1 were found to modify phage Kia so that its ability to form plaques on host KIN was lessened. The restricted phage formed plaques with high efficiency on all strains of lytic group 11. In general, it plated at lower titres on strains of lytic groups I, 111, IVY and on some strains of miscellaneous typing characteristics ; however, there were some variations among separate cultures of the same strains. For example, the restricted phage plated at high titre on strains 52~/79", 73, and PA, but formed significantly fewer numbers of plaques on strain 5 2~/ 7 9~ and on a second culture of 4 4~. Strain KIN was found to dissociate into apt (KIHI) and non-apt (mm) forms. The probability of plaque development by restricted phage on strain KIN was dependent upon the nutritional state of the cocci and also upon the proportion of apt and non-apt cells. The restriction of phage Kia was eliminated during its propagation on all strains other than lytic group 11. The unrestricted progeny particles tended to assay at equal titre on all the indicator strains. In all cases the genotype of the phage-susceptibility to host-control-remained unchanged. The observations add to existing data which indicate that strains of phage group I1 form a genetically distinct group. The suggestion is made that this phenomenon might help in taxonomic classification of strains of S . aureus.
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