SENSITIVITY OF ESCHERICHIA COLI TO VIRAL NUCLEIC ACID.

Abstract

Properties of several single-stranded DNA phages were investigated with special reference to their host factor requirements. Phages .vphi.B and G6 were inactivated by anti-.vphi.X174 serum but at different rates. Although host ranges were very similar, plating efficiencies of the 2 phages differed from each other on E. coli CR63.cntdot.1 and on C600.cntdot.1. Phage .vphi.C was immunologically remote from .vphi.B and G6 and, like G4, can infect C/15. At 42 C, .vphi.B and G6 could replicate in E. coli dna+ cells, but growth of G4, G13, G14 and U3 was restricted under this condition. Growth of .vphi.C was more thermosensitive and the free-phage yield at 35.degree. C was only 0.1% of the yield at 30.degree. C. Unlike .vphi.A, replication of G4, .vphi.C and U3 proceeded at 22.degree. C rather normally, but growth of .vphi.B and G6 was considerably retarded at this low temperature. In dna+ hcr+ hosts, multiplication of G6 and .vphi.B was inhibited by 1-2 mg/ml of hydroxyurea, 0.3% phenethyl alcohol, 10 .mu.g/ml of mitomycin C or 20 .mu.g/ml of nalidixic acid. In strain C infected with G6 or .vphi.B, formation of the parental RF [replicative form DNA] occurred in the presence of 200 .mu.g/ml of rifampicin, 50 .mu.g/ml of nalidixic acid, 50 .mu.g/ml of mitomycin C or 25 .mu.g/ml of chloramphenicol. Transfection experiments showed that replication of G6 depended on host functions determined by dnaB, -C(D), -E, -G, and -Z, and by ligts7 and rep3. The host products specified by these genes were also indispensable for .vphi.B.