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PubMed1979

Immunological properties of hyaluronidases associated with temperate bacteriophages of group A streptococci.

The antigenic relationships of hyaluronidases, bound and free, associated with temperate bacteriophages of group A streptococci were examined with antibody against purified whole phage and with antibody against phage-bound enzyme released by urea and purified to homogeneity. Studies performed by double diffusion in agar (ouchterlony) with antibody against the homologous purified enzyme from a temperate phage of a type 49 streptococcus indicated that the bound and free enzyme gave a single line of identity and that the free hyaluronidase activities in induced lysates of four strains of M type 49 streptococci were immunologically indistinguishable but different from the enzyme in induced lysates of a heterologous type. The four M type 49 strains were from widely different geographical or temporal sources and of different phage subtypes as determined by lyxic patterns. These findings were confirmed in studies that employed a functional assay of enzyme neutralization. An immunoglobulin preparation of antiserum against the purified enzyme as well as one against homologous purified whole phage neutralized the hyaluronidase activity produced by induction of the M type 49 strains and present either phage-bound or soluble in phage-free lysates. These immunoglobulin preparations had little effect on the hyaluronidase activities present in phage-lysates of other M types of group A streptococci. Inhibition of propagation of temperate phages by antibody against the purified phage hyaluronidase paralleled the neutralization of phage-associated enzyme activity by this antibody, indicating that antibody to the purified enzyme can inhibit phage infection. Antibody preparations against the purified phage-bound enzyme or against purified whole phage did not neutralize the extracellular hyaluronidase in the supernate of an uninduced culture of M type 4 streptococci. A human serum strongly inhibitory for the extracellular enzyme of this strain or on the purified phage enzyme from an M type 49 strain. The results support the view that the hyaluronidases associated with the temperate bacteriophages from various M types of group A streptococci do not share common antigenic determinants but that an immunological specificity exists that parallels the serologic specificity of the M protein of the host strains.

Antibody Specificity↗
PubMed1976

New temperate bacteriophage for Bacillus subtilis, rho 11.

A new temperate bacteriophage, rho11, isolated by J. Hoch, has been characterized. This new phage is very similar to the temperate phage phi3T in size (380 nm), host range, homoimmunity, DNA buoyant density (1.694 g/ml), antigenicity, and molecular weight (around 6.0 X 10(7)) as determined in gels. Like phi3T, rho11 converts thymine auxotrophs to prototrophy at high frequency (250 out of 250 tested). Phage rho11 differs from phi3T in plaque morphology and in the endonuclease R-EcoRI digest pattern. Sixteen of the 20 rho11 DNA fragments have migration patterns corresponding to those of the 21 fragments of phi3T. The close similarities yet clear differences between these phages suggest that the two phages have a common ancestor.

Bacillus subtilis↗
PubMed1978

Purification and characterization of a hyaluronidase associated with a temperate bacteriophage of group A, type 49 streptococci.

Urea treatment of a temperate bacteriophage from a type 49 strain of group A streptococcus (Streptococcus pyogenes) followed by ammonium sulfate fractionation, ion exchange, and affinity chromatography of solubilized proteins provided for the recovery (12%) and purification (44-fold) of the phage-associated hyaluronidase. The molecular weight of the homogeneous, purified enzyme was estimated to be 71,000 by polyacrylamide gel electrophoresis (in the presence of sodium dodecyl sulfate) and 75,000 by gel filtration with Sephacryl S-200. The enzyme has a pH optimum of 5.5, a Vmax of 0.1 absorbance unit/min per microgram of protein, and a Km of 4.8 X 10(-2) mg/ml with umbilical cord hyaluronic acid as substrate. Of the cations tested, calcium and magnesium were the only effectors of the enzyme. The enzyme is a glycoprotein (7.25% carbohydrate) containing glucose, galactose, and glucosamine. Analysis of the amino acid composition revealed a predominance of acidic amino acids and a relatively high content of cysteine. The partial specific volume, estimated from the amino acid and sugar analyses, was 0.725 cm3/g.

Amino Acids↗
PubMed1979

The role of temperate bacteriophage SP beta in prophage-mediated interference in Bacillus subtilis.

Virulent bacteriophage phi 1 grows on a variety of Bacillus subtilis strains, mutants of this virus which abortively infect the transformable bacillus. B. subtilis 168, while retaining the ability to productively infect related bacteria have been found. In the present study, we demonstrate that the inability of one such variant, phi 1m, to develop normally in strain 168 is mediated by cryptic prophage SP beta. The latter is a temperate bacteriophage which is carried by B. subtilis 168 and most strains derived from this bacterium. Phi 1 m infection of SP beta lysogens begins with apparently normal adsorption, penetration, and inititaion of virus-directed syntheses. At about the 20th min of the latent period, however, there is an abrupt cessation of nucleic acid synthesis and cellular respiration, accompanied by a change in cell permeability. This course of events can be altered to a permissive infection by mutation in the mpi gene of SP beta, by mutation in the spoOA gene of the host, or by growing SP beta lysogens at high temperature. In addition, we found a second class of phi 1 mutants which abortively infect B. subtilis 168 derivatives even in the absence of the SP beta prophage.

Bacillus subtilis↗
PubMed1977

Characterization of group H streptococcal temperate bacteriophage phi 227.

phi 227, a temperate phage from a group H streptococcus (Streptococcus sanguis), was propagated vegetatively in group H strain Wicky 4-EryR, and its characteristics were determined. A procedure dependent on multiplicity of infection, incubation time, and treatment of crude lysates with diatomaceous earth was found to optimize phage yield, resulting in titers of 1 X 10(10) to 2 X 10(10) PFU/ml. Without prior treatment with diatomaceous earth, subsequent purification procedures (methanol, ammonium sulfate, polyethylene glycol) gave recoveries of less than 1% of crude lysate titers. Adsorption of phi227 to host cells was relatively unaffected by the medium, but calcium (not substituted by magnesium) was required for formation of infectious centers. The phage receptor was present on purified cell walls, resisted trypsin and heat, and was removed ty hydrochloric acid, trichloracetic acid, and hot formamide: however, formamide-extracted material failed to inactivate phage, and the nature of the receptor is unknown. Single-step growth experiments showed a latent period of 39 min and a burst size of 100 PFU/infectious center; results were unaffected by omission of supplemental Ca2+, by supplementation with Mg2, addition of glucose, or changes of pH between 6.35 and 8.0; but increased temperature (40 to 43 degrees C) shortened the latent period and decreased the burst size. The latent period was prolonged in genetically competent host cells and in chemically defined medium; and in the latter, the burst size was smaller. Phage replication was sensitive to those metabolic inhibitors which inhibited the host streptococcus: these included rifampin, fluorodeoxyuridine, hydroxyurea, dihydrostreptomycin, and 6-P-hydroxyphenylazouracil. The data suggest that phi227 does not code for a rifampin-resistant RNA polymerase. However, in a rifampin-resistant host strain, phage replication and lysogen formation were both decreased suggesting that altered host core polymerase had less affinity for (some) promotors on the phi227 template. In transfection, a Ca2+-dependent stabilization step that was inhibited by Mg2+ was demonstrated; transformation was not affected by either Ca2+ or Mg2+, and the site and nature of the stabilization are unknown. More than one molecule of DNA was required for plaque formation. Biophysical characterization showed a type B phage of buoyant density (CsCl) 1.50, containing five proteins and 54.8% DNA. The duplex linear DNA had a molecular weight (calculated from contour length) of 23.2 X 10(6) and a guanine plus cytosine content (calculated from melting point) of 42.3 mol%. Similar characterizations of streptococcal phages, including biophysical data, have not been previously available.

Adsorption↗
PubMed1978

Early-blocked asporogenous mutants of Bacillus subtilis are lysogenized at reduced frequency by temperate bacteriophages.

The establishment of lysogeny in early-blocked asporogenous (Spo-) mutants of Bacillus subtilis 168, which were also defective in the production of antibiotics (Abs-), by temperate phage phi105 or SPO2 was studied. It was found that the frequency of lysogenization of Spo-Abs-mutants was 10 to 20% that of the wild-type bacteria. There was no difference in the efficiency of plating and the burst size of phi105 between wild-type and mutant strains. Phi105 lysogens of mutant strains were as stable as those of the wild type. Several rifampin-resistant mutants defective in the production of antibiotics were isolated. They were also defective in spore formation and lysogenized by phi105 at reduced frequency.

Anti-Bacterial Agents↗
PubMed1977

Incidence and properties of temperate bacteriophages induced from lactic streptococci.

Sixty-three strains of lactic streptococci isolated from commercial lactic streptococcal starter cultures were examined for lysogeny by treatment with ultraviolet light or mitomycin C. After treatment with the inducing agent, all strains, whether or not they lysed, were examined for evidence of phage release by electron microscopy. Thirty-eight strains yielded intact phages or phage particles of varying morphology. All the temperate phages had isometric heads and noncontractile tails; some had collars and structurally distinctive baseplates. Indicator host strains were found for phages induced from seven different strains. Three strains that released phages spontaneously yielded titers of 10(3) to 10(4) plaque-forming units per ml. When strains that spontaneously released phages were grown in mixed culture with indicator strains, increased phage titers of 10(6) to 10(7) plaque-forming units per ml were observed. These findings indicate that lysogenic lactic streptococcal strains may serve as a reservoir for phages that attack sensitive strains in mixed- or multiple-strain lactic starter cultures.

Bacteriophages↗
PubMed1977

Effects of x irradiation on a temperate bacteriophage of Haemophilus influenzae.

The inactivation of bacteriophage HP1c1 by X rays in a complex medium was found to be exponential, with a D0 (the X-ray exposure necessary to reduce the survival of the phage to 37%) of approximately 90 kR. Analysis of results of sucrose sedimentation of DNA from X-irradiated whole phage showed that the D0 for intactness of single strands was about 105kR, and for intactness of double strands, it was much higher. The D0 for attachment of X-irradiated phage to the host was roughly estimated as about 1,100 kR. Loss of DNA from the phage occurred and was probably due to lysis of the phage by X irradiation, but the significance of the damage is not clear. The production of single-strand breaks approaches the rate of survival loss after X irradiation. However, single-strand breaks produced by UV irradiation, in the presence of H2O2, equivalent to 215 kR of X rays, showed no lethal effect on the phage. Although UV-sensitive mutants of the host cell, Haemophilus influenzae, have been shown to reactivate UV-irradiated phage less than does the wild-type host cell, X-irradiated phage survive equally well on the mutants as on the wild type, a fact suggesting that other repair systems are involved in X-ray repair.

Bacteriophages↗
PubMed1977

Properties of four temperate bacteriophages active on Clostridium perfringens type A.

Four temperature bacteriophages (designated as PF1, PF2, PF3 and PF4) were isolated from lysogenic strains of Clostridium perfringens type A. On the basis of plaque morphology, pH stability, DNase and RNase resistance, buoyant density, one-step growth parameters and electron microscope phage dimensions, it seems that these phages are different and unrelated. Calcium was required for better phage replication. Bacterial strain S107 appears to be the only UV-inducible strain as compared with the other three lysogenic strains. PF2 has a unique pattern of pH stability showing two optima values: one at pH 5 and the second at pH 8-9. Generally, all four phages have a better resistance in acid than in alkaline pH values. The CsC1 equilibrium centrifugation patterns reveal low figures for phage PF1, PF2 and PF3 and show off the fact that PF4 lysates contain two viral particules different with respect to their densities, a property which other determinations failed to demonstrate. Each phage, except PF4, is well characterized by the parameters of the one-step growth cycle.

Bacteriophages↗
PubMed1977

Temperate Bacillus subtilis bacteriophage phi 3T: chromosomal attachment site and comparison with temperate bacteriophages phi 105 and SPO2.

The temperate Bacillus subtilis bacteriophage phi 3T contains within its genome a locus, designated thyP3, that encodes for a protein with thymidylate synthetase activity. Bacteriophage phi 3T is different from the two previously characterized temperate phages, phi 105 and SPO2, in: heteroimmunity, response to bacteriophage antisera, endonuclease digestion pattern, induction in the presence of 6-(p-hydroxyphenylazo)-uracil, and effect on the lytic cycle of bacteriophage phi 1. The mean burst size of phi 3T is 56. The dose response curve with bacteriophage phi 3T DNA is linear for transfection and transformation to the Thy+ phenotype. The inserted prophage has been mapped by PBS1 transduction; it is between chromosomal markers ilvA8 and gltA in the terminus of the chromosome. Thus thyP3 maps at a site separate from, but between, the bacterial markers thyA and thyB when thyP3 is in the prophage state.

Bacillus subtilis↗
PubMed1978

Restriction endonuclease mapping of bacteriophage phi105 and closely related temperate Bacillus subtilis bacteriophages rho10 and rho14.

Cleavage maps of the three similar Bacillus subtilis temperate bacteriophages, phi105, rho10, and rho14, were constructed by partial digestion analysis utilizing the restriction endonuclease EcoRI. Comparison of the topography of these maps indicates that all phage DNAs posses cohesive ends and a number of EcoRI restriction sites; the fragments are conserved, and the estimated base substitution/nucleotide divergence between these phages is 0.03 to 0.07 based on conserved fragments or between 0.03 and 0.11 based on conserved cleavage sites. These lines of evidence indicate that phi105, rho10, and rho14 are closely related. Double-enzyme digestion analysis reveals that rho14 DNA has unique SalGI and BglII restriction sites and phi105 DNA has a unique SalGI restriction site, making these phages possible cloning vectors for B. subtilis.

Bacillus subtilis↗
PubMed2025

Isolation and characterization of bacteriophages from clinical enterohemorrhagic Escherichia coli strains.

Temperate bacteriophages play a pivotal role in the biology of their bacterial host. Of particular interest are bacteriophages infecting enterohemorrhagic E. coli (EHEC) due to their significant contribution to the pathogenicity of its host, most notably by encoding the key virulence factor of this pathogen, the Shiga toxin. To better understand the role of EHEC phages on the functionality of its host, we isolated eight temperate phages from clinical EHEC isolates and characterized their genomic composition, morphology, and receptor targeting. Morphological analysis identified one long-tailed siphophage, targeting the OmpC receptor for host recognition, whereas the other seven phages are short-tailed podophages and target the essential BamA protein. Genomic characterization revealed significant variations between the long- and short-tailed phages. Five of the eight isolated phages encode the potent Shiga toxin. Comparative analysis displays the typical lambdoid mosaicism, indicative of horizontal gene transfer driving evolution. These findings provide insights into the genetic and morphologic diversity and receptor specificity of EHEC phages, highlighting their role in the evolution and pathogenicity of clinical EHEC strains.IMPORTANCECharacterizing bacteriophages from clinical EHEC isolates is crucial in understanding the mechanisms underlying bacterial evolution and virulence. Despite the clinical relevance of EHEC bacteriophages, they remain underexplored, and particularly phage receptors are often not characterized. Studying temperate EHEC phages is essential in the development of strategies to address the global burden of these foodborne infections. Notably, identifying the phage receptors is critical in unraveling the specific interaction between phage and host. Knowledge of the phage receptors can provide insights into the mechanisms of phage infection, host range, and bacterial resistance and is fundamental in the design of targeted therapies like new antimicrobials, phage therapy, or prevention of those infections.

Humans↗
PubMed1978

Transfection with replicating DNA from the temperate Bacillus bacteriophage phi 105 and with T4-ligase treated phi105 DNA: the importance in transfection of being longer than genome-length.

Replicating phage DNA extracted from Bacillus subtilis infected with phage phi 105 has a higher activity in transfection than mature DNA. By heteroduplex analysis it was shown that this DNA contains concatemeric molecules. Concatemers, constructed in vitro by treatment of mature DNA with T4-ligase also have an increased activity in transfection. DNA showing an increased activity in transfection does not have a requirement for more than one molecule per transfection event as is typically found for transfection with mature phi 105 DNA. An explanation is given for this difference suggesting that the structure of the ends of the transfecting molecules play an important role intransfection.

Bacillus subtilis↗
PubMed1978

Analysis of transposable elements inserted in the genomes of bacteriophages Mu and P1.

We have examined the genomes of the temperate bacteriophages Mu and P1 and some of their insertion mutants for hybridization with the prokaryotic transposable elements IS1 and IS2. We used the DNA blotting-hybridization technique in which denatured DNA fragments are transferred to nitrocellulose paper directly from agarose gels and hybridized to 32P-labeled probe DNA. The 800 base pair insertion in an X mutant of Mu was found to hybridize with IS1. The chloramphenicol resistance transposon, Tn9, in Mu X cam mutants was found to be located at or close to the sites of IS1 insertion in X mutants; Tn9 also hybridized with IS1. The restriction endonuclease BalI cleaved IS1 once; it cleaved Tn9 in all Mu X cam mutants twice to release a fragment of about 1700 base pairs. These results support the conclusion that Tn9 contains one copy of IS1 at each end. In the P1cam isolate, from which Tn9 was transposed to Mu, BalI made a third cut in Tn9 giving rise to fragments of about 850 base pairs. The data further suggested that Tn9 is present in tandem copies in the P1cam isolate we examined. P1 itself was found to harbor IS1. The two P1 strains tested had a common fragment containing IS1; one strain had an additional copy of IS1. The IS1 element common to the P1 strains was shown to be the site of the Tn9 insertion in the P1cam isolate examined. No hybridization between IS2 and any of the Mu and P1 strains could be detected.

Chloramphenicol↗
PubMed1978

Bacteriophage P22-mediated specialized transduction in Salmonella typhimurium: high frequency of aberrant prophage excision.

The temperate bacteriophage P22 mediates both generalized and specialized transduction in Salmonella typhimurium. Specialized transduction by phage P22 is different from, and less restricted than, the well characterized specialized transduction by phage lambda, due to differences in the phage DNA packaging mechanisms. Based on the properties of the DNA packaging mechanism of phage P22 a model for the generation of various types of specialized transducing particles is presented that suggests generation of substantial numbers of specialized transducing genomes which are heterogeneous but only some of which have terminally redundant ends. The primary attachment site, ataA, for phage P22 in S. typhimurium is located between the genes proA,B and supQ newD. (The newD gene is a substitute gene for the leuD gene, restoring leucine prototrophy of leuD mutant strains.) The proA,B and supQ newD genes are very closely linked and thus cotransducible by generalized transducing particles. Specialized transducing particles can carry either proA,B or supQ newD but not both simultaneously, and thus cannot give rise to cotransduction of the proA,B and supQ newD genes. This difference is used to calculate the frequency of generalized and specialized transducing particles from the observed cotransduction frequency in phage lysates. By this method, very high frequencies of supQ newD (10(-2)/PFU)- and proA,B (10(-3)/PFU)-specialized transducing particles were detected in lysates produced by induction of lysogenic strains. These transducing particles most of which would have been produced by independent aberrant excision events (which include in situ packaging), were of various types.

DNA, Viral↗
PubMed1979

Properties of Rhizobium trifolii isolates surviving exposure to specific bacteriophage.

Six strains of Rhizobium trifolii were exposed to specific bacteriophages and the properties of 10 surviving clones of each studied. Two temperate bacteriophages produced clones which were lysogenic but showed no changes in colony form, symbiotic properties, or somatic antigens. Of forty clones selected by exposure to four other bacteriophages, none were lysogenic although there was some indication of unusually long association of phage with bacteria in infected cultures. Seventeen of these clones were changed in symbiotic properties, 15 in colony morphology, and 13 in somatic cross-reaction with the parent. Unexpectedly, despite stringent selection conditions, 28 were still either partially or completely susceptible to the selecting phage.

Bacteriophages↗
PubMed1978

Bacteriophage P22-mediated specialized transduction in Salmonella typhimurium: identification of different types of specialized transducing particles.

The temperate bacteriophage P22 mediates both generalized and specialized transduction in Salmonella typhimurium. Specialized transduction by phage P22 is different from, and less restricted than, the well characterized specialized transduction by phage lambda, due to differences in the phage DNA packaging mechanism. Phage lysates produced by induction of lysogenic strains contain very high frequencies of supQ newD- and proA,B-specialized transducing particles (10(-2)/PFU and 10(-3)/PFU, respectively), most of which are produced by independent aberrant excision events of various types. In a model, 12 different modes of transduction mechanisms were characterized by: (i) the structure of the specialized transducing genomes after injection into a new host cell, i.e., linear or circular, and (ii) the requirements for the transduction process, i.e., host recombination functions, phage integration functions, or presence of a prophage. By using different recipient strains and phage helper strains, it was possible to show that most specialized transducing particles (ca. 99%) contain linear genomes that cannot circularize upon injection into a new host cell and that require the presence of an integrated prophage as a site for a recombinational event to give rise to a transductant. Only 0.1% of all specialized transducing particles were shown to transduce by integration, suggesting that transducing genomes containing terminally redundant ends represent only a minor fraction of all transducing particles that are produced. However, it should be pointed out that the frequency (approximately 10(-5)/PFU) of these specialized transducing genomes that can circularize upon injection into a new host cell is as high as or even higher than the frequency of specialized transducing particles of phage lambda. The remaining approximately 1% of all specialized transducing particles can transduce by any one of the other mechanisms described.

Adsorption↗