Infection of Protoplasts of Escherichia coli by Subviral Particles of Bacteriophage φX174

Abstract

Infection of protoplasts of various strains of Escherichia coli may be obtained with purified DNA preparations from bacteriophage φX174 made by two distinctly different methods. Infection of such protoplasts can also be obtained with nucleoprotein particles made from φX174 by heat treatment. None of the particles, infective to protoplasts, are infective to whole cells and all are infective to protoplasts of strains of bacteria usually resistant to whole φX174 virus. The protoplast-infective agents are in all cases destroyed by enzymatic treatment with DNase. The infective DNA is not inactivated by treatment with enzymatic amounts of trypsin but is by treatment with stoichiometric amounts, suggesting the formation of an inactive DNA-trypsin complex. Studies of the properties of protoplast infection indicate certain general characteristics which distinguish it from the more familiar virus infection of whole bacterial cells.

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