Abstract
Adams (1954) defined abortive infection as the loss of the plaque forming potential of infected bacteria under conditions which do not result in destruction of either free phage or uninfected bacteria. His discussion was primarily concerned with the abortion of infection caused by certain chemical agents, for instance, as 5-methyl tryptophane, but the purpose of his paper was, as he stated there, to look for generalization, if any, to be drawn concerning this phenomenon. Benzer (1952) discovered a type of abortive infection which proceeded in starved bacterial cells infected with bacteriophage T2r, and a more extensive study of this kind of phenomenon was conducted by Gross (1954a; 1954b) . At first, the term “abortive adsorption” was used by Benzer for the phenomenon, but Gross proposed to call it “abortive infection” because of the lack of experiments permitting the isolation of the specific phase of infection during which the loss of infective centers occurred.
The phenomenon called abortive infection by Gross is actually concerned with the incapability of a fraction of the starved bacterial population ofEsherichia. coil, K12 to support the synthesis of bacteriophage T2r. However, Lwoff (1953) employed the term“abortive phage development”in his review of lysogeny, where a strain of B. megateriumlysogenized by a bacteriophage is subjected to lysis with production of no bacteriophages when induced by ultraviolet irradiation. So far unknown is a relation between two phenomena both called“abortive”.
The invasion of the bacteriophage into a host cell is another problem. Hershey revealed that the phage DNA is introduced into a host cell through the tail of the phage, with which this is attached to its host cell (Hershey, 1953) . Puck (1954), Puck, Garen and Cline (1951), and Puck and Sagik (1953) analyzed experimentally several factors involved in cell attachment and penetration by bacterial viruses; primary virus cell attachment, which occurs through electrostatic binding, is followed by virus penetration, of which the first step is thought to be principally constituted by a phenomenon of splitting the virus into protein and DNA particles. According to them completion of virus penetration is influenced upon by several factors. In a normal process the splitting of the virus into protein and DNA parts is immediately followed by the injection of the splitted DNA into the cell, but in some abnormal cases the splitted DNA may be liberated into the external medium.
Luria and Steiner (1954) investigated the role of calcium ion in the first step of bacteriophage T5 infection. Phage T5 adsorbed on its host cell is inactivated fairly rapidly in the absence of calcium or magnesium ion and even in the presence of adequate concentrations of calcium the penetration process is rather slow requiring several minutes for its completion. This result agrees quite well with Lanni's finding (Lanni, 1954) obtained by a different procedure.
During the experiments concerning host-range mutation of T2 bacteriophage, a mutant ofE. coli, strain B was obtained whose behavior towards T2 phage was fairly peculiar and may throw some light on the phenomenon of abortive infection as well as penetration process of T2 bacteriophage. The present paper is devoted to describe the analyses of the process of abortive infection of T2 phage in the mutant of E. coli, strain B.
