STUDIES ON THE RELATIONSHIP BETWEEN VIRUS AND HOST CELL

Abstract

Infection of E. coli with P³² labelled T2r⁺ bacteriophage resulted in the con version of a part of the isotope to a form soluble in 5% trichloroacetic acid. This acid soluble phosphorus was used as a measure of the breakdown of the virus. When the phage to cell ratio was less than unity a two step breakdown curve was obtained corresponding to the two cycles of infection in this type of experi ment. The heights of the steps represented 5 and 32% breakdown, the second rise commencing after about 25 min. Multiple infection of cells yielded a curve which rose without inflection to about 23% breakdown at 20 min. after which there was little further increase. When the addition of radioactive phage was preceded by sufficient nonradioactive phage to infect most of the cells in the culture, the amount of breakdown of labelled virus increased to about 55% within 20 min. at which time breakdown practically ceased. Control experi ments indicated that dead phage in the labelled preparations contributed little to the acid soluble P³² fraction in these experiments and that the breakdown resulted from infection of the cells by virus. It is suggested that infection of cells by phage stimulates some mechanism whereby phage adsorbed to the cell at a later time is broken down extensively at the cell surface. The experimental results are interpreted in the light of this concept.