Acridine orange-sensitized photoinactivation of T4 bacteriophage. II. Genetic studies with photoinactivated phage

Mutagenesis of free and intracellular cyanophage AS-1 by ultraviolet, N-methanyl-N'-nitro-N-nitrosoguanidine and acriflavine

Mutagenic actions of ultraviolet irradiation (UV), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and acriflavine (photodynamic) were tested in free and intracellular phage AS-1 infecting Anacystis nidulans IU625. Spontaneous and induced mutations with particular reference to host range (h) and minute plaque formation (m) were investigated. The spontaneous mutation frequencies varied from 10(-9) to 10(-8) and from 2 X 10(-5) to 2 X 10(-4) for h and m mutants respectively. UV was efficient in inducing h and m markers in free phage particles as well as intracellular phage; MNNG induced both markers in intracellular phage only, and acriflavine induced m mutants only in free as well as in infecting phages. UV-induced mutations in free phage were photo-reactivable by visible light. With all the mutagens used, maximal induction of both markers was observed with treatment of 2-h complexes.

Photodynamic inactivation of antigenic determinants of single-stranded DNA bacteriophage phi chi 174

Bacteriophage phiX174 when photodynamically inactivated (i.e., when rendered unable to produce plaques as a result of exposure to visible light in air in the presence of proflavine) progressively lost their capacity to bind efficiently with homologous antiserum. Such loss of serum-blocking power was evident with heat-inactivated but not with UV-irradiated phage. The ability of the phages to adsorb to host cells, however, remained practically unaltered even after photodynamic inactivation. It thus appears that photodynamic damages in the so-called "jacket" component of the phiX174 coat proteins are partly responsible for the loss of plaque-forming ability, whereas the "spikes" are either poor antigens or insensitive to photodynamic treatment.

Reactivation of photoinactivated single-stranded DNA bacteriophage phi X174 by UV-irradiated Escherichia coli cells

Reactivation of single-stranded DNA phage, photodynamically inactivated in the presence of proflavine sulfate, by three isogenic Escherichia coli strains having different DNA repair capabilities has been studied. It was found that reactivation of photoinactivated phiX174 was possible only if the host cells were recombination proficient (recA(+)) and had been lightly irradiated with UV light prior to infection; the presence of the uvrA(+) gene was not essential. Only a small part of the proflavine-mediated photodynamic damage in phiX174 could be repaired in this fashion. Burst sizes of reactivated phages were, however, comparable to those of normal unirradiated phages.

Identification of the block in the intracellular replication of single-stranded DNA of photodynamically inactivated bacteriophage phi X174

(32)P-labeled single-stranded DNA phage phiX174 was photodynamically inactivated by irradiation in air with visible light in the presence of the acridine dye, proflavine sulfate. The inactivated phages could adsorb to the host cells but failed to lyse them. Formation of intracellular mature phages was almost completely inhibited. Photodynamic lesions in phiX174 DNA caused intracellular formation of defective double-stranded replicative form molecules which ultimately reverted to the single-stranded configuration.