title: In Vitro system for the study of bacteriophage phi chi 174 adsorption and eclipse.
abstract: An in vitro system was developed for the study of the initial stages of bacteriophage phi chi 174 infection. Escherichia coli C cells were incubated with 20% sucrose and then subjected to cold osmotic shock in 5 mM MgSO4. The concentrated supernatant shock fluid inactivated phi chi 174 with the same kinetics and requirements as for normal infection. Shock fluids prepared from phi chi 174-resistant strains of E. coli did not show this effect. The 114S phage were initially converted into 70S particles, the process termed "eclipse". These structurally altered phages then attached to a component of the shock fluid, producing fast-sedimenting complexes, and eventually released at least a part of their DNA into the medium. The fast-sedimenting complex could be radioactively labeled with oleic acid. Radioactivity was found to co-chromatograph with both biological activity and the majority of the high-molecular-weight carbohydrates present in the shock fluid. It is concluded that E. coli C osmotic shock fluid contains isolated phi chi 174-specific receptor sites composed of lipopolysaccharides. This system conveniently separates the early stages of phage phi chi 174 infection from the intracellular events.
mesh_terms: D000327:Adsorption; D001665:Binding Sites; D002250:Carbon Radioisotopes; D002462:Cell Membrane / Q000382:microbiology*; D002501:Centrifugation, Zonal; D003080:Cold Temperature; D003090:Coliphages / Q000254:growth & development*; D004267:DNA Viruses / Q000254:growth & development; D004279:DNA, Viral / Q000302:isolation & purification; D004926:Escherichia coli; D008070:Lipopolysaccharides / Q000302:isolation & purification; D008278:Magnesium Sulfate; D009829:Oleic Acids; D009995:Osmosis; D013997:Time Factors; D014316:Tritium; D014779:Virus Replication
chemical_list: D002250:Carbon Radioisotopes; D004279:DNA, Viral; D008070:Lipopolysaccharides; D009829:Oleic Acids; D014316:Tritium; D008278:Magnesium Sulfate