Host Controlled Variation in Bacterial Viruses

Abstract

Passage through new hosts or new tissues is a widely used method for altering the properties of viruses. In some instances selection of spontaneous mutants has been demonstrated to be the mechanism causing the variation (Luria, 1945). Nonhereditary mechanisms sometimes have been postulated, but since no such case has been analyzed sufficiently, it is often assumed that selection of mutants is the only possible mechanism. A detailed analysis of two cases of variation in two different bacterial viruses is reported in this paper. In both these cases we are dealing with nonheritable alterations stemming directly from passage through a new host and not with mutations. A somewhat similar case of host controlled variation involving other bacterial viruses has been reported recently by Luria and Human (1952). MATERIAL AND METHODS Baceria. The following bacterial strains were used: (a) Escherichia coli, strain 5, a nonlysogenic derivative of strain K-12 (Weigle and Delbrick, 1951); (b) E. coli, strain C (no. 122 of the National Collection of Type Cultures, London); (c) Shigella dysnterie, strain Sh (Bertani, 1951); (d) E. coli, strain B. A derivative of C, strain C/1,5, resistant to phages Ti and T5, and a streptomycin resistant derivative of Sh, strain Sh/s, were also used. Phages. The following bacteriophages were 1 This work was supported by grants from the American Cancer Society, as recommended by the Committee on Growth of the National Research Council, and from The National Foundation for Infantile Paralysis. The authors are greatly indebted to Miss Shirley J. Nice for assistance; to Dr. Margaret Lieb for contributing information on phage desorption; to Dr. R. K. Appleyard for contributing data on the distribution of the "exceptional" plaques formed by XC on S; and finally to Drs. Max Delbruck and S. E. Luria for discussing the manuscript.

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A century of bacteriophage research and applications: impacts on biotechnology, health, ecology and the economy!

“…The host bacteria appeared to modify the phage so that phages with the incorrect modification were restricted in their replication in certain strains. 31,32 It was only 20 years later that genetic and biochemical studies revealed that this is caused by certain sequence-specific host endonucleases, now universally in use as restriction enzymes. The existence and role of messenger RNA was proven with phage-infected cells.…”

Molecular noise of innate immunity shapes bacteria-phage ecologies

“…Despite the ubiquity of RM systems in prokaryotic genomes [17], basic ecological and evolutionary aspects of these otherwise simple genetic elements are poorly understood [20]. Although RM systems have been discovered more than six decades ago due to their ability to protect bacteria from phage [32] and this is often assumed to be their main function [33], only a few experimental studies focused on the ecological and evolutionary dynamics of interactions between RM systems and phage [34,35]. Similarly, eects of RM systems on their host bacteria, such as their cost in individual bacteria due to self-restriction, began to be addressed quantitatively only recently [24,36].…”