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At least 163 records · Page 9Linked to original sources
PubMed1995

Monoclonal antibody against pIII of filamentous phage: an immunological tool to study pIII fusion protein expression in phage display systems.

UNLABELLED: A monoclonal antibody directed against the gene 3 product (pIII) of filamentous phage M13 was produced to study pIII-fusion protein expression in E. coli and its incorporation in the phage capsid. The protein was gel-purified from E. coli expression cultures harboring the genetic information of pIII under the control of an inducible lac promoter. To study pIII-fusion protein expression, phage display systems were applied in which either the whole pIII or the C-terminal half was used (McCafferty et al. (1990) Nature (London) 348, 552-554; Szardenings and Collins (1990) Gene 94, 1-7; Barbas and Lerner (1991) In: METHODS: Companion to METHODS in Enzymology, Combinatorial Immunoglobulin Libraries on the Surface of Phage (Phabs): Rapid Selection of Antigen-Specific Fabs, Vol. 2, Academic Press, Orlando, pp. 119-124). In all cases, the monoclonal antibody was able to detect the native and the recombinant protein in E. coli and on the phage tip using non-denaturing (ELISA) and denaturing (SDS-PAGE, immunoblot analysis) conditions. All selected pIII-specific monoclonal antibodies were found to be directed against epitopes within amino acids 198 to 406 of pIII, which is necessary for capsid incorporation and therefore included in all pIII-mediated phage display designs.

Animals↗
PubMed2003

Construction of high-density display of CD147 ectodomain on VCSM13 phage via gpVIII: effects of temperature, IPTG, and helper phage infection-period.

Production of VCSM13 phage displaying a high density of CD147 ectodomain (CD147Ex) was achieved when culturing conditions were modulated. A phagemid expressing CD147Ex was constructed and used to produce phage display CD147Ex gpVIII fusion protein in TG1 Escherichia coli. Displaying of CD147Ex via gpVIII was successfully increased when growing the transformed TG1 at 25 degrees C with IPTG-stimulation. In addition to temperature and IPTG-stimulation, the VCSM13 helper phage infection-period particularly affected the insertion of CD147Ex into phage progeny. By sandwich ELISA, incorporation of the CD147Ex into phage particle was confirmed. The correct size of the CD147Ex-gpVIII fusion protein at 28kDa was demonstrated by Western immunoblotting. Multivalent display of CD147Ex on phage particles will be valuable in discovering its ligand partner.

Antigens, CD↗
PubMed2002

Scavenger receptor block as strategy for the identification of bone marrow homing phages by panning in vivo random peptide phage displayed libraries.

Surface molecules exclusively expressed by cells of the bone marrow (BM) are candidate targets for delivering therapeutic agents to this tissue. To identify ligands specific for the BM, we performed a series of pannings in vivo with random peptide phage displayed libraries (RPPDL). We could show that phages bind to bone marrow endothelium (BME) independently of the peptide insert, suggesting that the BM, similarly to spleen and liver, is part of the reticulo-endothelial system (RES). Furthermore, this strong "natural" affinity to the BME was abrogated by polyanions, indicating that phage trapping by this endothelium is mediated by scavenger receptors (SR). To circumvent interference by SR, polyinosinic acid was administered before phage panning in vivo. This led to the identification of a consensus motif that confers binding specificity for a subpopulation of hemopoietic marrow cells. Thus, SR inhibition, by avoiding phage trapping by the endothelium, seems to allow phage particles to extravasate and reach parenchymal cells. Accordingly, this panning strategy in vivo may be useful for the identification of targeting motifs specific for cells located in the extravascular space of various tissues.

Amino Acid Motifs↗
PubMed2000

The R-type pyocin of Pseudomonas aeruginosa is related to P2 phage, and the F-type is related to lambda phage.

Pseudomonas aeruginosa produces three types of bacteriocins: R-, F- and S-type pyocins. The S-type pyocin is a colicin-like protein, whereas the R-type pyocin resembles a contractile but non-flexible tail structure of bacteriophage, and the F-type a flexible but non-contractile one. As genetically related phages exist for each type, these pyocins have been thought to be variations of defective phage. In the present study, the nucleotide sequence of R2 pyocin genes, along with those for F2 pyocin, which are located downstream of the R2 gene cluster on the chromosome of P. aeruginosa PAO1, was analysed in order to elucidate the relationship between the pyocins and bacteriophages. The results clearly demonstrated that the R-type pyocin is derived from a common ancestral origin with P2 phage and the F-type from lambda phage. This notion was supported by identification of a lysis gene cassette similar to those for bacteriophages. The gene organization of the R2 and F2 pyocin gene cluster, however, suggested that both pyocins are not simple defective phages, but are phage tails that have been evolutionarily specialized as bacteriocins. A systematic polymerase chain reaction (PCR) analysis of P. aeruginosa strains that produce various subtypes of R and F pyocins revealed that the genes for every subtype are located between trpE and trpG in the same or very similar gene organization as for R2 and F2 pyocins, but with alterations in genes that determine the receptor specificity.

Amino Acid Sequence↗
PubMed2001

Influence of phage population on the phage-mediated bioluminescent adenylate kinase (AK) assay for detection of bacteria.

AIMS: The effect of phage concentration on the activity of adenylate kinase (AK) released from the cells lysed during infection was investigated in order to optimize a bioluminescent phage-mediated method for bacterial enumeration. METHODS AND RESULTS: The number of bacteria lysed by phages specific to Salmonella enteritidis and E. coli was determined using a bioluminescent method for the detection of AK released. In order to optimize the assay, the effect of phage concentration and time of infection on the amount of AK released was investigated. The release of AK was greatest at a multiplicity of infection (moi) of 10-100. CONCLUSION: The amount of AK released from Salmonella enteritidis and E. coli G2-2 cells by specific phages, SJ2 and AT20, respectively, depended on the type of bacteria, the stage of growth, the nature of phage, moi and time. SIGNIFICANCE AND IMPACT OF THE STUDY: An assay is described which allows detection of E. coli and Salmonella Enteritidis within 2 h at levels of 103 cfu ml-1.

Adenylate Kinase↗
PubMed1997

Production of a single-chain fragment of the murine anti-idiotypic antibody ACA125 as phage-displayed and soluble antibody by recombinant phage antibody technique.

The F(ab')2 fragment of the murine monoclonal anti-idiotypic antibody ACA125 mimicking the tumor-associated antigen CA125 is used as a vaccine for the induction of an anti-tumoral immunity in patients with ovarian carcinoma. We tried to generate a single-chain fragment (ScFv) composed of ACA125 heavy- and light-chain variable domains connected by a polypeptide linker as an alternative to the corresponding F(ab')2 fragment. Heavy- and light-chain genes of antibody-producing mouse hybridoma cell line were amplified separately and assembled into a ScFv gene with linker DNA by the polymerase chain reaction (PCR). The ScFv gene was ligated into the phagemid vector pCANTAB5E, which allows the production of both phage-displayed and soluble ScFv. Transformed Escherichia coli TG1 cells were infected with M13K07 helper phage to yield recombinant phage, which display ScFv fragments as a g3p fusion protein on the surface of the filamentous phage M13. Recombinant phages could be selected by binding to the idiotypic antibody OC125 after one round of panning and directly used to reinfect E. coli TG1 cells. The E. coli nonsuppressor strain HB2151 was infected with an antigen-positive phage clone, previously screened by enzyme-linked immunosorbent assay (ELISA), to express soluble ScFv fragments. Functional soluble ScFv binding to the idiotypic antibody OC125 F(ab')2 could be detected in the bacterial periplasm by Western blot and ELISA. The variable heavy- and light-chain genes of the ACA125 ScFv fragment were further sequenced and compared with known antibody sequences.

Amino Acid Sequence↗
PubMed1983

Nonideal statistics and positive correlation in phage recombination: studies with lambda tandem duplication phages.

The question of nonideality in phage recombination, that is, the extent to which recombinant frequencies differ from those expected from the proportions of the two parental types in the mass culture, was addressed by experiments with lambda tandem duplication phages. Isolation and genotypic analysis of triplication-phage progeny, all of which must be the result of intermolecular recombination, yielded a value of about 0.5 for the nonideality parameter h, i.e., the frequency of unlike-parent matings was only about 1/2 the "ideal" value. This value was independent of multiplicity and about the same for the Rec or Red recombination systems. Similar analysis of single-copy phage progeny yielded estimates of k, the ratio of intramolecular to intermolecular recombination of about 1/6 for the Rec system; no intramolecular events were detected in Red-mediated crosses. Consideration of known nonideality factors (finite input, limited number of intracellular sites for phage growth) suggests that the observed h values correspond to intracellular mixing efficiencies of 55 to 100%, depending on the number of intracellular phage growth sites assumed. Analysis of long-range positive correlation (negative interference) indicates that statistical effects caused unlike-parent double crossovers to be three to four times as frequent as an independent-event calculation would predict. In addition, Rec-mediated crosses showed a 1.3-fold positive correlation for unlike-parent crossovers (in a second interval) among the progeny of like-parent recombinations.

Bacteriophage lambda↗
PubMed2005

2004 ASM Conference on the New Phage Biology: the 'Phage Summit'.

In August, more than 350 conferees from 24 countries attended the ASM Conference on the New Phage Biology, in Key Biscayne, Florida. This meeting, also called the Phage Summit, was the first major international gathering in decades devoted exclusively to phage biology. What emerged from the 5 days of the Summit was a clear perspective on the explosive resurgence of interest in all aspects of bacteriophage biology. The classic phage systems like lambda and T4, reinvigorated by structural biology, bioinformatics and new molecular and cell biology tools, remain model systems of unequalled power and facility for studying fundamental biological issues. In addition, the New Phage Biology is also populated by basic and applied scientists focused on ecology, evolution, nanotechnology, bacterial pathogenesis and phage-based immunologics, therapeutics and diagnostics, resulting in a heightened interest in bacteriophages per se, rather than as a model system. Besides constituting another landmark in the long history of a field begun by d'Herelle and Twort during the early 20th century, the Summit provided a unique venue for establishment of new interactive networks for collaborative efforts between scientists of many different backgrounds, interests and expertise.

Bacteria↗
PubMed1984

Differentiation of lactic streptococcal phages into phage species by DNA-DNA homology.

Twenty-five lactic streptococcal bacteriophages were differentiated by DNA homology into four species. Complete correlation was found between DNA homology groups and morphological characteristics of the phages except that two phage types, which differed in only the presence or absence of a collar, were one species by DNA homology. These findings were supported by serological data and differences in DNA molecular weights of the proposed species. The complete lack of homology between these phage species indicates that they are unlikely to have a recent common phage ancestor and that one morphological type of phage has not been derived by mutation from a phage of another morphological type.

Bacteriophages↗
PubMed1995

Proposals for optimization of the international phage typing system for Listeria monocytogenes: combined analysis of phage lytic spectrum and variability of typing results.

Combined analysis of 5,179 serial phage reactions of 20 Listeria monocytogenes propagating strains over 14 years and phage typing results from 2,659 further L. monocytogenes strains allowed us to estimate lytic spectrum specificity and the variability of the lytic reactions of 35 phages. These included the 26 phages recommended for the international method for phage typing defined in 1985 by Rocourt et al. (J. Rocourt, A. Audurier, A. L. Courtieu, J. Durst, S. Ortel, A. Schrettenbrunner, and A. G. Taylor, Zentralbl. Bakteriol. Abt. 1 Orig. A 259:489-497, 1985). The results are discussed individually for each phage. Proposals for modifying the present system are made with the aim of producing an optimal bacteriophage set for routine use.

Bacteriophage Typing↗
PubMed1995

Identification of related genes in phages phi 80 and P22 whose products are inhibitory for phage growth in Escherichia coli IHF mutants.

Bacteriophage lambda grows in both IHF+ and IHF- host strains, but the lambdoid phage phi 80 and hybrid phage lambda (QSRrha+)80 fail to grow in IHF- host strains. We have identified a gene, rha, in the phi80 region of the lambda(QSRrha+)80 genome whose product, Rha, inhibits phage growth in an IHF- host. A search of the GenBank database identified a homolog of rha, ORF201, a previously identified gene in phage P22, which similarly inhibits phage growth in IHF- hosts. Both rha and ORF201 contain two possible translation start sites and two IHF binding site consensus sequences flanking the translation start sites. Mutations allowing lambda (QSRrha+)80 and P22 to grow in IHF- hosts map in rha and ORF201, respectively. We present evidence suggesting that, in an IHF+ host, lambda(QSRrha+)80 expresses Rha only late in infection but in an IHF- host the phage expresses Rha at low levels early in infection and at levels higher than those in an IHF+ host late in infection. We suspect that the deregulation of rha expression and, by analogy, ORF201 expression, is responsible for the failure of phi80, lambda(QSRrha+)80, and P22 to grow in IHF mutants.

Amino Acid Sequence↗
PubMed1999

Sequence of Shiga toxin 2 phage 933W from Escherichia coli O157:H7: Shiga toxin as a phage late-gene product.

Lysogenic bacteriophages are major vehicles for the transfer of genetic information between bacteria, including pathogenicity and/or virulence determinants. In the enteric pathogen Escherichia coli O157:H7, which causes hemorrhagic colitis and hemolytic-uremic syndrome, Shiga toxins 1 and 2 (Stx1 and Stx2) are phage encoded. The sequence and analysis of the Stx2 phage 933W is presented here. We find evidence that the toxin genes are part of a late-phage transcript, suggesting that toxin production may be coupled with, if not dependent upon, phage release during lytic growth. Another phage gene, stk, encodes a product resembling eukaryotic serine/threonine protein kinases. Based on its position in the sequence, Stk may be produced by the prophage in the lysogenic state, and, like the YpkA protein of Yersinia species, it may interfere with the signal transduction pathway of the mammalian host. Three novel tRNA genes present in the phage genome may serve to increase the availability of rare tRNA species associated with efficient expression of pathogenicity determinants: both the Shiga toxin and serine/threonine kinase genes contain rare isoleucine and arginine codons. 933W also has homology to lom, encoding a member of a family of outer membrane proteins associated with virulence by conferring the ability to survive in macrophages, and bor, implicated in serum resistance.

Attachment Sites, Microbiological↗
PubMed2003

Novel type of specialized transduction for CTX phi or its satellite phage RS1 mediated by filamentous phage VGJ phi in Vibrio cholerae.

The main virulence factor of Vibrio cholerae, the cholera toxin, is encoded by the ctxAB operon, which is contained in the genome of the lysogenic filamentous phage CTX phi. This phage transmits ctxAB genes between V. cholerae bacterial populations that express toxin-coregulated pilus (TCP), the CTX phi receptor. In investigating new forms of ctxAB transmission, we found that V. cholerae filamentous phage VGJ phi, which uses the mannose-sensitive hemagglutinin (MSHA) pilus as a receptor, transmits CTX phi or its satellite phage RS1 by an efficient and highly specific TCP-independent mechanism. This is a novel type of specialized transduction consisting in the site-specific cointegration of VGJ phi and CTX phi (or RS1) replicative forms to produce a single hybrid molecule, which generates a single-stranded DNA hybrid genome that is packaged into hybrid viral particles designated HybP phi (for the VGJ phi/CTX phi hybrid) and HybRS phi (for the VGJ phi/RS1 hybrid). The hybrid phages replicate by using the VGJ phi replicating functions and use the VGJ phi capsid, retaining the ability to infect via MSHA. The hybrid phages infect most tested strains more efficiently than CTX phi, even under in vitro optimal conditions for TCP expression. Infection and lysogenization with HybP phi revert the V. cholerae live attenuated vaccine strain 1333 to virulence. Our results reinforce that TCP is not indispensable for the acquisition of CTX phi. Thus, we discuss an alternative to the current accepted evolutionary model for the emergence of new toxigenic strains of V. cholerae and the importance of our findings for the development of an environmentally safer live attenuated cholera vaccine.

Bacteriophages↗
PubMed2005

Llama antibodies against a lactococcal protein located at the tip of the phage tail prevent phage infection.

Bacteriophage p2 belongs to the most prevalent lactococcal phage group (936) responsible for considerable losses in industrial production of cheese. Immunization of a llama with bacteriophage p2 led to higher titers of neutralizing heavy-chain antibodies (i.e., devoid of light chains) than of the classical type of immunoglobulins. A panel of p2-specific single-domain antibody fragments was obtained using phage display technology, from which a group of potent neutralizing antibodies were identified. The antigen bound by these antibodies was identified as a protein with a molecular mass of 30 kDa, homologous to open reading frame 18 (ORF18) of phage sk1, another 936-like phage for which the complete genomic sequence is available. By the use of immunoelectron microscopy, the protein is located at the tip of the tail of the phage particle. The addition of purified ORF18 protein to a bacterial culture suppressed phage infection. This result and the inhibition of cell lysis by anti-ORF18 protein antibodies support the conclusion that the ORF18 protein plays a crucial role in the interaction of bacteriophage p2 with the surface receptors of Lactococcus lactis.

Amino Acid Sequence↗
PubMed1976

[Phage typing of cholera vibrios with different sets of phages].

A comparative study was made of two sets of Mukerjee and Drozhevkina-Arutyunova's bacteriophages in typing 514 strains of the El Tor vibrios and 45 strains of clasic biotype. It was shown that the Mukerjee or Drozhevkina-Arutyunova's phages could be used for the typing of cholera vibrios. The phages of the latter set prove to detect more phage types (18 against 11); they determine both the phage type and the biotype at the same time. The typing of cholera vibrios of both biotypes is possible, and the percentage of nontyping strains left is comparatively low (5.2 against 23.5 after Mukerjee). A table of the phage correspondence was made; it permits to obtain comparable data in using any set of the typing phages.

Bacteriophage Typing↗
PubMed2005

[Construction of human phage antibody library and screening and characterization of phage antibodies against N terminal fragment of human lipopolysaccharide binding protein].

AIM: To construct human phage antibody library and to prepare phage antibodies against N terminal fragment of human lipopolysaccharide binding protein (NH-LBP). METHODS: NH-LBP was expressed in insect cells sf21 cultured with serum-free culture medium (SF-900 II) by BAC-TO-BAC baculovirus expression system. Human antibody library (Fab) was constructed by phage display system (pComb3H/VCSM13) and screened with NH-LBP. RESULTS: NH-LBP was successfully expressed in insect cells sf21 cultured with serum-free culture and effectively purified via affinity chromatography column with TALON resin. About 8 mg NH-LBP was obtained. Human combinatorial phage display antibody library consisting of 5.0 x 10(8) CFU was constructed. After eight rounds of panning with NH-LBP we got 3 phage antibodies with high affinity for NH-LBP (DNA sequences and amino acid sequences of kappa chains of these antibodies were deposited in GenBank (AY337713 and AY337714). CONCLUSION: Phage antibodies against NH-LBP were obtained successfully, which lays the foundation for preparing disulfide stabilized Fv fragments antibody (dsFv) against NH-LBP, understanding the function of LBP in vivo, and prevention and therapy of excessive inflammatory reaction.

Acute-Phase Proteins↗
PubMedDate not supplied

[The level of spontaneous phage production and sensitivity to melioidosis phages of museum cultures of Pseudomonas pseudomallei].

The phage-producing activity and sensitivity of museum cultures of a melioidosis agent to melioidosis phages have been studied. Most cultures show spontaneous phage-production, though its level differs in strains. Some of the melioidosis cultures demonstrate lack of phages. The fact that these strains have different sensitivity to chloroform lysate of cultures producing phages indicates their possible lysogenic state. Electron microscopy has shown the presence of at least tow morphological types of phages in P. pseudomallei C-141. These data confirm existence of polysogeny in the melioidosis agent.

Bacteriophage Typing↗
PubMed1986

[Coupling and rec-independence of the processes of replication and transposition of Pseudomonas aeruginosa phage D3112. The effect of the phage genes controlling the replication of DNA of D3112].

D3112 phage was shown to replicate via the process of coupled replication--transposition: the phage DNA is not excised from the chromosome after prophage induction and new phage copies insert into many different sites. The transposition is controlled by two D3112 early genes--A (mapped in the 1.5-3 kbp region) and B (3-4.5 kbp), and requires intact attL site (involvement of the phage right end attR not studied). D3112 is capable to transpose RP4 plasmid into the chromosome; both the D3112 and RP4 transpositions are rec-independent. The product of the early C gene which is not required for D3112 transposition has pleiotropic effect on the development of D3112 and is necessary for the process of D3112 DNA excision from the chromosome, for cell lysis as well as for mature phage production. We suggest that this gene is responsible for positive regulation of D3112 late genes expression, similar to the C gene of Mu phage or Q gene of lambda. Mutations in four D3112 late genes ts25, ts35, ts73 and ts110 do not affect transposition or excision processes. No detectable (less than 0.02 copies per cell) amount of linear or circular D3112 DNA is formed during the replication--transposition. Hence, in the course of replication and transposition processes D3112 genome has its ends permanently bound covalently to the chromosome. The excision of the D3112 DNA takes place at late stages.

Bacteriophages↗