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PubMed1997

Evaluation of seven experimental phages for inclusion in the international phage set for the epidemiological typing of Listeria monocytogenes.

The purpose of our study was to evaluate the inclusion of seven experimental phages into the international phage set for subtyping Listeria monocytogenes. The seven additional phages included the broad-host-range virulent Myoviridae phage A511 (M. J. Loessner, Appl. Environ. Microbiol. 57:1912-1918, 1991), three temperate phages from the Danish subsystem for typing serotype 1/2 strains (12682, 6223, and 5775) (P. Gerner-Smidt, V.T. Rosdahl, and W. Frederiksen, APMIS 101:160-167, 1993), and three temperate phages isolated by this laboratory in France (9425, 1313, and 197). A panel of 395 Listeria monocytogenes isolates (including 180 that were non-phage typeable by the international set) were used in the study for a comparison of the lytic spectra of the various bacteriophages. These results showed that the inclusion of five of the experimental phages contributed greatly to the overall typeability and discriminatory power of the system, especially for strains within serogroup 1/2.

Animals↗
PubMed2004

The Lactococcal abortive phage infection system AbiP prevents both phage DNA replication and temporal transcription switch.

We describe here a new lactococcal abortive phage infection system, designated AbiP. AbiP is effective against some lactococcal phages of one prevalent group, 936, but not against phages from the other two groups (c6A and P335). It was identified in the Lactococcus lactis subsp. cremoris strain IL420, on the native plasmid pIL2614. AbiP is encoded by a single gene, expressed in an operon with a second gene. In this work, abiP is shown to affect both the replication and transcription of phage DNA. In AbiP(+) cells, phage DNA replication is arrested approximately 10 min after infection. Levels of middle and late phage transcripts are lower in AbiP(+) than in AbiP(-) cells, probably due to the smaller amount of phage DNA. By contrast, early phage transcripts are more abundant in AbiP(+) than in AbiP(-) cells, suggesting that the switch-off, which occurs 15 min after infection in AbiP(-) cells, is prevented in AbiP(+) cells.

Bacterial Proteins↗
PubMed1976

Use of phage F-phi WJ-1 of Mycobacterium fortuitum to discern more phage types of Mycobacterium tuberculosis.

A total of 125 strains of Mycobacterium tuberculosis from the Southeastern area of the United States was subjected to phage typing. In addition to the five major mycobacteriophages, a new phage, F-phi WJ-1, was used in the study. The results obtained with the five major phages were: type A0, 35.2%; TYPE B, 29.6%, and type C, 4.0%. The remaining 21.2% of the strains phaged typed as subgroups A1 through A6. These percentages were similar to the typing results of earlier studies. The new phage, F-phi WJ-1, subdivided each of the phage types, with the exception of type C, into two subgroups. The possible role of host modification-restriction of the phages used in phage typing of strains of M. tuberculosis is discussed.

Bacteriophage Typing↗
PubMed1994

Differentiation of Salmonella enteritidis phage type 8 strains: evaluation of three additional phage typing systems, plasmid profiles, antibiotic susceptibility patterns, and biotyping.

Three additional phage typing systems for Salmonella enteritidis, plasmid analysis, biochemical tests, and antimicrobial susceptibility tests, were used in an attempt to subdivide 30 phage type 8 (phage typing system used by the WHO International Center for Enteric Phage Typing, London, England) isolates. These isolates represented 18 different egg-related outbreaks (21 strains) and 9 reference strains or strains that were not egg-associated. Only 7 of the 30 strains (28%) were subdivided by one or more of the methods used; this included 3 of the 21 strains from egg-related outbreaks. Twenty-seven strains contained a 55-kb plasmid that is associated with S. enteritidis. Of 65 additional phages tested, 2 from the phage typing system obtained from the Pasteur Institute, Paris, France, were useful in differentiating the three strains that lacked the 55-kb plasmid. Although the results obtained for the 21 strains from egg-related outbreaks showed that the strains had minor phenotypic differences, the overall results suggested that the strains may represent a single clone. Studies are planned to test additional phages and other typing methods to see whether strains of phage type 8 can be further differentiated.

Bacterial Typing Techniques↗
PubMed1975

Studies on a smooth phage resistant variant of Brucella abortus II. Mechanism of phage resistance.

The properties of a smooth phage resistant variant of Brucella abortus were studied in an attempt to determine the mechanism of phage resistance. This strain was fully capable of adsorbing phage but penetration, and hence replication, did not occur. No evidence of lysogeny or a phage carrier state could be obtained and gross chemical differences between the resistant strain and its phage susceptible parent were not detected. The phage resistant variant showed increased resistance to lysis from without, either by phage or by lysozyme, in the presence of chelating agents. It was concluded that resistance was the result of a modification in cell wall structure conferring resistance to lysozyme-like enzymes, thus preventing penetration of phage.

Adsorption↗
PubMedDate not supplied

Intestinal colonization and organ invasion in chicks experimentally infected with Salmonella enteritidis phage type 4 and other phage types isolated from poultry in the United States.

Phage type 4 Salmonella enteritidis strains have only recently been isolated from poultry and humans in the United States, although this phage type predominates in many other countries. The present study assessed the ability of S. enteritidis isolates of various phage types found in the United States (including phage type 4) to colonize the intestinal tract and invade to reach internal organs in experimentally infected chicks. Groups of 5-day-old single-comb white leghorn chicks were inoculated with a range of oral doses of three phage type 4 isolates and three isolates of other phage types. Although some significant differences were observed between individual S. enteritidis isolates in the frequencies at which they colonized the intestinal tracts and invaded to reach the spleens of inoculated chicks, no consistent overall pattern differentiated phage type 4 isolates from isolates of other phage types.

Animals↗
PubMed1997

Isolation of Vibrio cholerae 0139 phages to develop a phage typing scheme.

Five V. cholerae 0139 phages isolated from different parts of India have been used for phage typing study. A strain isolated from Nagpur city (NPR-4) was used as the host for phage propagation. All but one of the 260 strains of V. cholerae 0139 were found to be typeable and could be clustered into 8 distinct phage types as revealed by lytic patterns. Phage type 1 was the predominant type (61.15%) followed by type 2 (18.46%). The strains isolated from Madras exhibited 7 out of 8 phage types. These newly isolated phages could be adopted for phage typing of V. cholerae 0139 strains as an epidemiological tool.

Bacteriophage Typing↗
PubMed1998

Phage display: applications, innovations, and issues in phage and host biology.

In the 7 years since the first publications describing phage-displayed peptide libraries, phage display has been successfully employed in a variety of research. Innovations in vector design and methods to identify target clones account for much of this success. At the same time, not all ventures have been entirely successful and it appears that phage and host biology play important roles in this. A key issue concerns the role played by a displayed peptide or protein in its successful expression and incorporation into virions. While few studies have examined these issues specifically in context of phage display, the literature as a whole provides insight. Accordingly, we review phage biology, relevant aspects of host biology, and phage display applications with the goals of illustrating (i) relevant aspects of the interplay between phage-host biology and successful phage display and (ii) the limitations and considerable potential of this important technology.

Amino Acid Sequence↗
PubMed1976

[Effect of mutagens on RNA-containing phages and its infectious RNA. VII. Genetic nature of morphologic mutants of RNA-containing phage MS2].

Temperature-sensitive "leaky" mutants of phage MS2 having white dense ring around negative colonies are described. As these mutants are used for quantitative genetic studies, the white ring presents interest. Typical mutant 40 is used as a model for investigation. Light microscopy has shown, that cells from white ring zone have spore-like inclusions, which determine the characteristic structure of surrounding mutant negative colonies. Cytochemical reactions for the presence of glicogen, lipids, volutin, nuclear material and spores were negative. Electrone microscopy of negatively stained samples and ultrathin sections has revealed that cells from white ring zone, unlike phage-infected wild type cells, have two types of electron dense inclusions: 1) crystalline structures formed with great number of closely packed mature phage particles, and 2) large amorphic bodies. Electrone microscope-cytochemical data showed that inclusions remain intact under treatment of ultrathin sections of white zone ring with DNase and perchloric acid, while nuclear material was completely destroyed. Amorphic bodied were completely destructed after the treatment with RNase, while nuclear material and crystalline phage aggregated remained unchanged. Therefore, amorphic bodies consist of RNA, which has not been used to form virions. Single cycle of the development of mutant 40 at 37 degrees and 43 degrees C and under the temperature of incubation 37 degrees leads to 43 degrees C and 43 degrees leads to 37 degrees C in the course of intracellular reproduction is investigated. Influence of the phage on growth on infected culture is studied. The data obtained draw to a conclusion that the impaired function belongs to cystron protein of the phage membrane. As certain mutations in this cystrone of RNA-containing phage result in the depression of cystrone RNA polymerase, it is supposed that the formation of RNA containing bodies in infected cells, determining the formation of white rings in NA, together with cristalline aggregates of cells, is a result of mutation damage of cystrone protein of the phage MS2 membrane.

Coliphages↗
PubMed2026

Magnetite facilitates phage-bacteria interactions and phage-associated metabolic coordination for medium-chain fatty acid biosynthesis under ammonia stress.

Medium-chain fatty acid (MCFA) production from waste activated sludge (WAS) is considered to rely on the syntrophic interactions among distinct functional microorganisms. Whether phages represent an overlooked ecological component involved in MCFA biosynthesis remains unclear. MCFA production is often inhibited by high total ammonia nitrogen (TAN). Conductive materials have been proposed as effective strategies to enhance or recover MCFA production under TAN stress. Therefore, the inhibition-recovery system could provide a useful framework for investigating whether viral ecological responses are associated with MCFA-related metabolic processes. In this study, magnetite (Fe3O4) was selected as the recovery strategy of MCFA production under TAN stress. Results showed that a total of 3915 vOTUs and 118 metagenome-assembled genomes were recovered from the anaerobic bioreactors subjected to three conditions: Control (without TAN stress), TAN stress, and TAN stress with Fe3O4 presence. Under high TAN environment (∼5 g/L), MCFA production reduced by 49% (1.3 g COD/L) in comparison to that without high TAN stress. The ecological coupling between temperate phages and MCFA-related bacterial hosts was weakened, accompanied by substantial decreases in the abundance and transcriptional abundance of phage-associated auxiliary metabolic genes (AMGs) related to MCFA synthesis (e.g., fatty acid biosynthesis, acyl-chain metabolism). In the presence of Fe3O4 (i.e., 10 g/L), MCFA production was four and two times higher than those with and without high TAN stress. In addition to enhanced phage-bacteria ecological coupling and increased the abundance and transcription of AMGs related to MCFA formation, Fe3O4 increased the abundance and expressions of electron-transfer-related AMGs (e.g., cbb3-type cytochrome c oxidase, type IV pilus assembly genes) and QS-related LuxR-family and HTH-type regulators, indicating that such indirect pathway could be largely overlooked during MCFA synthesis. This is also the first-time reporting that phages could represent an ecological layer responsive to iron oxide. Analyses of publicly available metagenomes collected from MCFA-oriented anaerobic systems further confirmed that phages could be broadly associated with the metabolic processes involved in MCFA biosynthesis. Taken together, this study reveals that phages could serve as an overlooked ecological layer associated with MCFA metabolism and provide a viral-ecology perspective for understanding TAN inhibition and iron oxide-mediated recovery during WAS-to-MCFA bioconversion.

Ammonia inhibition↗
PubMed1994

Cytotoxin-converting phages, phi CTX and PS21, are R pyocin-related phages.

phi CTX is a temperate phage of Pseudomonas aeruginosa harbouring the ctx gene that encodes cytotoxin (CTX). We identified phi CTX as an R pyocin-related phage, by serological and molecular analysis, based on the findings that the infectivity of the phage was inhibited with the antisera directed R pyocins and R pyocin-related phages and that the phi CTX genome showed DNA homology to the genome of PS17 (a representative of the R pyocin-related phages) as well as to the pyocin R2 genes. Another new CTX-converting, R pyocin-related phage named PS21 was isolated from a CTX-producing strain of P. aeruginosa, suggesting the distribution of the ctx gene by certain members of R pyocin-related phage family.

ADP Ribose Transferases↗
PubMed1980

Computer analysis of Staphylococcus aureus phage typing data from 1957 to 1975, citing epidemiological trends and natural evolution within the phage typing system.

Computer analysis of Staphylococcus aureus phage ty ping data collected for over 18 years in a large research hospital showed a drastic decrease in the number of hospital epidemic strains. Phage lysis patterns gradually modified from those of earlier years and were a reflection of changes within the S. aureus reservoir, and not within the typing phages, since the typing phages were used from stable lyophilized stocks. There was increasing cross-lysis of S. aureus strains by phages of lytic groups I, II, and III, such that this grouping was no longer epidemiologically valid. A 61% increase in unique strains occurred from the period 1957 to 1975. Disappearance of the widely recognized epidemic strains was followed by a proliferation of unique strains with individual phage patterns. These increased from 38% in the period 1957 to 1962 to 62% in the period 1969 to 1975, indicating a trend toward a "one patient-one strain" situation. Nontypable strains decreased in more recent years from 16% (1957 to 1975) to 7% in 1978, following introduction of phages 94, 96, 292, and D-11. Pandemic S. aureus strain 80/81 first appeared in this hospital in 1959, 5 years after it was first reported in the United States. Strain 80/81 disappeared from the hospital in 1963, partly due to the advent of methicillin.

Bacteriophage Typing↗
PubMed1978

Preliminary results of phage typing of coagulase-negative staphylococci with the set of typing phages of Pulverer and co-workers.

120 strains of Staphylococcus epidermidis isolated from clinical material were typed with the set of 16 test phages described by Pulverer et al. (1975). 58 (48%) strains were typable with RTD and additionally 12 strains with 100 times RTD. The pattern Ph10/U14/U16 was observed most common (36 strains), followed by the pattern U14/U16 (11 strains). One strain showed lysis reactions with all typing phages. With 61 strains phage U14 gave a lysis whereas phage U20 reacted only with 4 strains. The S. epidermidis phages were not specific for this species, at least some of these showed lysis reactions with S. aureus strains. The lysis pattern most often observed was Ph10/U14/U16. There was no correlation between the patterns given by the S. aureus test phages and those by the S. epidermidis phages.

Bacteriophage Typing↗
PubMed1992

Involvement of phage T5 tail proteins and contact sites between the outer and inner membrane of Escherichia coli in phage T5 DNA injection.

The penetration of phage T5 DNA into the Escherichia coli envelope takes place through ion channels (Boulanger, P., and Letellier, L. (1992) J. Biol. Chem. 267, 3168-3172). To identify putative phage protein(s) involved in the formation of these channels, E. coli cells were infected at 37 degrees C with radioactively labeled phage and their envelopes were fractionated. After a flotation gradient, proteins belonging to the phage tail were recovered both in fractions containing the contact sites between the inner and outer membranes and in the outer membrane. The electrophoretic banding pattern of phage proteins indicates that the contact sites were enriched in the protein pb2. Moreover, infected cells were significantly enriched in contact sites as compared to intact cells. There was no enrichment of contact sites and very little radioactivity was found in this fraction and in the outer membrane when the cells were infected at 4 degrees C (i.e. under conditions where the phage does not inject its DNA). These results suggest that both contact sites and pb2 may play a central role in the translocation of phage T5 DNA.

Centrifugation, Density Gradient↗
PubMed1976

Specialized transducing phages derived from phage P22 that carry the pro AB region of the host, Salmonella typhimurium: genetic evidence for their structure and mode of transduction.

Two independently isolated specialized transducing phages, P22pro-1 and P22pro-3, have been studied. Lysates of P22pro-1 contain a majority of transducing phages which can go through the lytic cycle only in mixed infection; these defective phages transduce by lysogenization in mixed infection and by substitution in single infection. A few of the transducing phages in P22pro-1 lysates appear to be non-defective, being able to form plaques and to transduce by lysogenization in single infection. Transduction by P22pro-3 lysates is effected by non-defective transducing phages, which transduce by lysogenization; these lysates also contain a majority of defective phages which do not co-operate in mixed infection. The P22pro-1 genome is thought to contain an insertion of bacterial DNA longer than the terminal repetition present in P22 wild type, so that at maturation a population of differently defective phages is produced. The exact structure of the P22pro-3 genome is open to conjecture, but it seems clear that the insertion of bacterial DNA is smaller than that in P22pro-1. Both P22pro-1 and P22pro-3 are defective in integration at ataA under non-selective conditions, although both integrate on medium that lacks proline.

Chromosome Mapping↗
PubMed1980

Sub-classification of phage types of Salmonella weltevreden and typing of strains by an extended phage typing scheme.

By the use of two adapted phage preparations of Typing phage II the S. weltevreden phage types 4 and 5 could be classified into two sub-types each and phage types 9 and 10 into three sub-types each. the 1094 strains of S. weltevreden could be classified into a total of sixteen phage types including the sub-types. The host range mutants of Typing phage II were distinct from the parent strain. After adaptation to two insensitive strains, one of the new preparations, phi IIA lost its affinity to some strains which were lysed by the parent phage strain but gained lytic affinity for a few others that were originally insensitive. The second preparation phi IIB showed an increase in lytic range as expected. Antigenically these preparations were shown to be related but not identical. The possible reasons for serological non-identity of host range mutants with the parent strain have been discussed.

Bacteriophage Typing↗
PubMed1995

Monoclonal antibodies against a minor and the major coat proteins of filamentous phage M13: their application in phage display.

We have produced monoclonal antibodies (MAbs) which react with a minor and the major coat proteins of filamentous phage M13 and have characterised them by combining the techniques of enzyme-linked immunosorbent assay (ELISA) and Western blotting. These coat proteins are the minor coat protein, gIIIp, the product of gene III and the major coat protein, gVIIIp, the product of gene VIII. Both gIIIp and gVIIIp are important in the context of 'phage display' of foreign peptides/proteins as fusions to these proteins. The anti-gIIIp MAbs were able to detect native gIIIp as well as the fusion proteins comprising foreign proteins and gIIIp in ELISA and on Western blot, indicating their utility for studying the expression of foreign proteins in phage display. Similarly anti-gVIIIp MAbs detected gVIIIp both in ELISA and on Western blot. In an 'affinity capture phage ELISA', phages that were captured by virtue of the interaction between the foreign protein (ligand fused to the gIIIp and displayed on the phage surface) and the immobilised counterpart (receptor), could be easily detected using anti-gVIIIp MAbs. Considering the potential of 'phage display' technology in protein engineering, these antibodies should find wide applications.

Antibodies, Monoclonal↗
PubMed1991

Phage typing and phage induction in carrier and invasive Staphylococcus epidermidis isolates.

Fifty-nine Staphylococcus epidermidis isolates (30 carrier and 29 invasive) were phage typed using the phage set developed by Pulverer. Poor results were obtained as only 24% of the invasive and 27% of the carrier isolates were typable, with no differences between these percentages (P greater than 0.05). Isolation of lysogenic phages present in the isolates was attempted by three different methods, induction being satisfactory only by overnight incubation with 0.1 mg l-1 mitomycin C and detection with 2,3,5-triphenyl-tetrazolium chloride. All isolates produced phages, and the lytic activity of these phages was expressed on more than 50% of the isolates in all cases (except one phage which lysed 10% of the carrier isolates and 13.8% of the invasive isolates). The percentages of isolates lysed in the two groups (carrier and invasive) were statistically different (P less than 0.05) only for phages derived from four isolates.

Bacteriophage Typing↗