Complexes of F-Pili and RNA Bacteriophage

Abstract
Cell-free filtrates of F+ strains of Escherichia coli "inactivate" RNA phages. The active agents have been identified in the electron microscope as thin appendages called F-pili. Complexes of F-pili and phage may be easily assayed because of their retention by membrane filter pads. Calcium ion is required for formation of the complex.