Author SummaryCampylobacter jejuni is the major cause of bacterial food-borne illness worldwide. Predation of C. jejuni by virulent bacteriophage offers the prospect of controlling bacterial populations at source in poultry. We report that in chickens, bacteriophage resistance is infrequent because the mutants that escape bacteriophage are not proficient in poultry colonisation but readily revert back to colonisation-proficient phage-sensitive types. Bacteriophage resistance is generated by reversible genomic scale inversions, leading to the activation of an unrelated bacteriophage integrated into the bacterial genome. These data not only suggest that bacteriophage therapy of C. jejuni would remain a sustainable measure to reduce poultry contamination but also demonstrate how bacterial genomes can evolve under the strong and widespread pressure of bacteriophage predation in the environment.
Read TL, the new bacteriophage of Pseudomonas aeruginosa and its application for the search of halo-producing bacteriophages, Russian Journal of Genetics on DeepDyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips.
While the harmful effects of lactic acid bacterial bacteriophages in the dairy industry are well-established, the importance of Bacillus subtilis-infecting bacteriophages on soybean fermentation is poorly-studied. In this study, we isolated a B. subtilis-infecting bacteriophage BSP10 from Meju (a brick of dried fermented soybean) and further characterized it. This Myoviridae family bacteriophage exhibited a narrow host range against B. subtilis strains (17/52, 32.7%). The genome of bacteriophage BSP10 is 153,767 bp long with 236 open reading frames and 5 tRNAs. Comparative genomics (using dot plot, progressiveMauve alignment, heat-plot, and BLASTN) and phylogenetic analysis strongly suggest its incorporation as a new species in the Nit1virus genus. Furthermore, bacteriophage BSP10 was efficient in the growth inhibition of B. subtilis ATCC 15245 in liquid culture and in Cheonggukjang (a soybean fermented food) fermentation. Artificial contamination of as low as 102 PFU/g of bacteriophage BSP10 during
Bacteria and their viruses (phages) are abundant across diverse ecosystems and their interactions influence global biogeochemical cycles and incidence of disease. Problematically, both classical and metagenomic methods insufficiently assess the host specificity of phages and phage-host infection dynamics in nature. Here we review emerging methods to study phage-host interaction and infection dynamics with a focus on those that offer resolution at the single-cell level. These methods leverage ever-increasing sequence data to identify virus signals from single-cell amplified genome (SAG) datasets or to produce primers/probes to target particular phage- bacteria pairs (digital PCR and phageFISH), even in complex communities. All three methods enable study of phage infection of uncultured bacteria from environmental samples, while the latter also discriminates between phage-host interaction outcomes (e.g., lytic, chronic, lysogenic) in model systems. Together these techniques enable quantitative,
TY - JOUR. T1 - Antibody response to bacteriophage hyaluronidase in acute glomerulonephritis after group A streptococcal infection. AU - Halperin, Scott A.. AU - Ferrieri, Patricia. AU - Gray, Ernest D.. AU - Kaplan, Edward L.. AU - Wannamaker, Lewis W.. PY - 1987. Y1 - 1987. N2 - In a test of the hypothesis that lysogeny of group A streptococci by a temperate bacteriophage might confer nephritogenicity, 283 sera from 69 patients were examined for IgG and IgM antibodies to M 49 streptococcal bacteriophage hyaluronidase. The IgG and IgM response to bacteriophage hyaluronidase was greatest in M 49 streptococci-infected individuals with nephritis, but M 49 streptococci-infected subjects without nephritis also had a greater immune response than did subjects infected with serotypes other than M 49. Although antibody to bacterial hyaluronidase was detected in all Streptococcus-infected groups, antibody to M 49 streptococcal bacteriophage hyaluronidase usually was found in only M 49 ...
A major limitation with traditional phage preparations is the variability in titer, salts, and bacterial contaminants between successive propagations. Here we introduce the Phage On Tap (PoT) protocol for the quick and efficient preparation of homogenous bacteriophage (phage) stocks. This method produces homogenous, laboratory-scale, high titer (up to 1010-11 PFU·ml−1), endotoxin reduced phage banks that can be used to eliminate the variability between phage propagations and improve the molecular characterizations of phage. The method consists of five major parts, including phage propagation, phage clean up by 0.22 μm filtering and chloroform treatment, phage concentration by ultrafiltration, endotoxin removal, and the preparation and storage of phage banks for continuous laboratory use. From a starting liquid lysate of | 100 mL, the PoT protocol generated a clean, homogenous, laboratory phage bank with a phage recovery efficiency of 85% within just two days. In contrast, the traditional method took
In our country Diarrheal epidemics occur seasonally. Two peaks of outbreaks agreeably coincide with dry season and monsoon rain. Several factors control the outbreaks to occur and collapse. Bacteriophages are one of them which have been reported to trigger the collapse of the outbreaks. The concentration of the Vibrio cholerae specific bacteriophages is inversely correlated with the concentration of Vibrio cholerae in the environment. Therefore bacteriophages probably play an essential role in controlling the epidemics to occur or collapse. It is still not clear what factors trigger the onset of Diarrheal outbreaks. This study was design to see the effect of E. coli bacteriophages on the epidemics of Diarrheal disease. Routine isolation, estimation and molecular characterization reveal the prevalence E. coli phage. We have tried to characterize the isolated phages by analyzing the DNA using the technique called restriction fragments length polymorphism (RFLP ...
The detection and quantification of enteric RNA viruses is based on isolation of viral RNA from the sample followed by quantitative reverse transcription polymerase chain reaction (RT-qPCR). To control the whole process of analysis and in order to guarantee the validity and reliability of results, process control viruses (PCV) are used. The present article describes the process of preparation and use of such PCV- MS2 phage-like particles (MS2 PLP) - in RT-qPCR detection and quantification of enteric RNA viruses. The MS2 PLP were derived from bacteriophage MS2 carrying a unique and specific de novo-constructed RNA target sequence originating from the DNA of two extinct species. The amount of prepared MS2 particles was quantified using four independent methods - UV spectrophotometry, fluorimetry, transmission electron microscopy (TEM) and a specifically developed duplex RT-qPCR. To evaluate the usefulness of MS2 PLP in routine diagnostics different matrices known to harbor enteric RNA viruses (swab
Bacteriophages escaping from a dying bacterial cell (Streptococcus sp.), coloured scanning electron micrograph (SEM). This bacteriophage was discovered in freshwater near a sewage outlet. A bacteriophage, also known as a phage, is a virus (virion) that infects a bacterium. It consists of a head (capsid), containing the genetic material (either RNA or DNA) and usually a tail and tail fibres (not seen), which the phage uses to attach to a specific receptor sites on the bacterium. This specific binding means that a bacteriophage can only infect certain bacteria bearing specific receptors. Once attached to the cell surface genetic material is injected into the bacterium, taking over the bacteriums own cellular machinery and forcing it to produce more copies of the bacteriophage. When sufficient numbers have been produced the phages escape from the bacterium by cellular lysis, killing the bacterium in the process. Magnification: x21,335 when shortest - Stock Image C032/0258
Food treated with bacteriophage, as to reduce or prevent the growth of undesirable bacteria. The food treated comprises: a food product; a first, fatty or waxy coating layer on the food product; and a second coating layer comprising one or more bacteriophage strains, wherein the fatty or waxy coating layer is distinct from the coating layer comprising the one or more bacteriophage strains. The food may be coated with bacteriophage and rubbed to distribute the phage on the food surface. The food may be preferably a pet food. The food may be coated in two or more layers. A process for treating food with bacteriophage comprises contacting the food with the bacteriophage and rubbing the coated food surface. The coating and/or rubbing may be performed in vibratory conveyor.
Gómez P., Bennie J., Gaston K.J. & Buckling A. (2015) The Impact of Resource Availability on Bacterial Resistance to Phages in Soil. PLoS ONE 10(4): e0123752.. Resource availability can affect the coevolutionary dynamics between host and parasites, shaping communities and hence ecosystem function. A key finding from theoretical and in vitro studies is that host resistance evolves to greater levels with increased resources, but the relevance to natural communities is less clear. We took two complementary approaches to investigate the effect of resource availability on the evolution of bacterial resistance to phages in soil. First, we measured the resistance and infectivity of natural communities of soil bacteria and phage in the presence and absence of nutrient-providing plants. Second, we followed the real-time coevolution between defined bacteria and phage populations with resource availability manipulated by the addition or not of an artificial plant root exudate. Increased resource ...
This chapter focuses on the doublestranded DNA (dsDNA) phages, and especially on the temperate phages. While virulent phages certainly perform transduction and engage in evolutionary sparring with their hosts and so influence their evolution, the chapter focuses mainly on the complex interactions of temperate phages with their hosts. Bacteriophages may thus have contributed to the current compact nature of bacterial genomes. The approximately 100 currently published bacterial genome complete nucleotide sequences, and about 285 prophages are related to known bacteriophages. Of the more than 280 prophages in the currently sequenced bacterial genomes, only a few are known to be fully functional bacteriophages. There are two rather complex types of genetic entity in which this appears to have happened: the phage tail-like bacteriocins and the gene transfer agents. To date, protection from other phages and disease virulence factors are the lysogenic conversion genes that have been discovered and studied in
The Pseudomonas genus is a big problem mainly for the poultry food industry. The shelf life of chicken carcasses stored under refrigeration is limited by the appearance of undesirable odors and sliminess surface generated primarily by Gram negative bacteria. Due to the subsequent emergence of resistant bacteria, is necessary proving new alternatives as guaranty the microbiological quality of foods and human health. Bacteriophages or phages are viruses of bacteria that use resources of bacteria for their replication and killing bacteria naturally, showing them as a potential tool for bacteria biocontrol in food industry. In this study, 11 bacteriophages were isolated from the exudate product of defrost of chicken carcasses using as host strains Pseudomonas aeruginosa (ATCC 25619) and Pseudomonas fluorescens (ATCC 13525). This study also aimed at the purification, quantification and morphological and molecular characterization of phages (RFLP). Bacteriophage can be found in all types of ...
Since 2006, the United States Food and Drug Administration (FDA) and United States Department of Agriculture (USDA) have approved several bacteriophage products. LMP-102 (Intralytix) was approved for treating ready-to-eat (RTE) poultry and meat products. In that same year, the FDA approved LISTEX (developed and produced by Micreos) using bacteriophages on cheese to kill Listeria monocytogenes bacteria, giving them generally recognized as safe (GRAS) status.[23] In July 2007, the same bacteriophage were approved for use on all food products.[24] In 2011 USDA confirmed that LISTEX is a clean label processing-aid and is included in USDA.[25] Research in the field of food safety is continuing to see if lytic phages are a viable option to control other food-borne pathogens in various food products. In 2011 the FDA cleared the first bacteriophage-based product for in vitro diagnostic use.[26] The KeyPath MRSA/MSSA Blood Culture Test uses a cocktail of bacteriophage to detect Staphylococcus aureus in ...
In the article, Dr Mohammed and Dr Millard discuss the issue of antibiotic resistance and warned that we are on the cusp of a post-antibiotic era. They outlined how viruses that infect and kill bacteria, known as bacteriophages (phages), may be a possible alternative to antibiotics. They wrote: Bacteriophages can survive in many environments, including deep sea trenches and the human gut. While phages are efficient killers of bacteria, they dont infect human cells and are harmless to humans.. They added: Lytic bacteriophages are preferred for treatment because they dont integrate into the bacterial hosts chromosome. But it is not always possible to develop lytic bacteriophages that can be used against all types of bacteria.. Dr Mohammed and Dr Millard indicated that for bacteriophages to become commonplace for curing infections, there needs to be more research into the area of how bacteriophages interact with bacteria.. Read the full article on The Conversations website.. ...
Bacteriophages are viruses that attack bacteria--their name means bacteria eater in Latin. Here, you can see a bunch of bacteriophages on the surface of a bacterial cell. They look sort of like balloons tethered to the surface of the moon. They were discovered near the dawn of the twentieth century, and at first they enjoyed…
Bacteriophage T4 viruses. 3D computer illustration of multiple T4 bacteriophage viruses. A bacteriophage, or phage, is a virus that infects bacteria. Enterobacteria T4 infects E. coli bacteria. It consists of an icosahedral (20-sided) head, which contains the genetic material, a tail (cylindrical) and tail fibres (leg-like). The tail fibres attach to the surface of the bacterium and the tail injects a DNA (deoxyribonucleic acid) strand into the cell. The viral genetic material then hijacks the bacteriums own cellular machinery, forcing it to produce more copies of the bacteriophage. When a sufficient number have been produced, the phages burst out of the cell, killing it in the process. - Stock Image C024/7526
Sigma-Aldrich offers abstracts and full-text articles by [Thomas Denes, Henk C den Bakker, Jeffrey I Tokman, Claudia Guldimann, Martin Wiedmann].
Given a recent increase in the number of bacteriophage genome sequenced- Nathan ( @NathanMB3) has updated the all-v-all comparison with more genomes (~5500 in total).Image at bottom of page. After reading the recent paper MASH:fast genome and metagenome distance and estimation using MinHash and meeting Nathan Brown at the University of Leicester, we discussed using MASH for identification of phage genomes and comparison thereof. The authors of the genome biology paper had included viruses in the microbial comparison in Figure 3 . Here we just focused on bacteriophage genomes.. For rapid identification of phage genomes we first constructed a database of phage genomes that were public. This included all phage genomes from the NCBI (ftp://ftp.ncbi.nlm.nih.gov/genomes/Viruses/all.fna.tar.gz) , which were then filtered to remove eukaryotic viruses. In addition phage genomes were collected from the phagesdb.org website. A sketch was made for all of these phages and collated, the mash database of ...
Phage transduction is used to move selectable genetic markers from one donor strain to another recipient strain. Nat Sternberg, among others, pioneered the use of phage P1 to move genetic elements in E. coli and the use of the Cre/Lox system from P1 for controlled recombination. Today, phage P1 is commonly used as a transducing agent because it is a generalized tranducer (it can package random sections of the host chromosome instead of its own genome) giving rise to transducing particles. P1vir is a mutant phage that enters the lytic cycle upon infection (ensuring replication and lysis). During the replication and lysis of the phage in a culture of bacteria, a small percentage of the phage particles will contain a genome segment that contains your gene of interest. P1 packages approximately 90 kb of DNA, so you can transduce genes that are linked to a selectable marker. Once a phage population has been generated from a donor host, the phage are used to infect a recipient host. Most of the ...
Hi all, I am looking for a way or a tool to map all the GC rich (of given percentage say, 60% or 70% GC) short stretches of nucleotides anywhere between 20-80 base pairs in Bacteriophage T4 and other Phage genomes.I could not find such a tool at NCBI website. I highly appreciate your help. Thank you so much Kiran ...
Bacteriophages (phages) are obligate intracellular parasites of bacteria. The basic life cycle of phages involves the use of bacterial cellular metabolism for production of new phage particles, release of those particles from their cellular confines, and then infection of new host cells (1). Phage infection is initiated by the phage binding to a specific receptor on the surface of the host bacterium, followed by the delivery of the phage genome to the host cell. Adsorption involves multiple steps, including reversible binding for the initial recognition and proper positioning, followed by irreversible binding to the final receptor. However, the molecular mechanisms by which phages deliver their genomes into a host are far from being elucidated.. Generally, a phage is able to infect a limited number of bacterial strains or related strains of the same species (2, 3). Interactions between a phage and the host bacteria is primarily dependent on the nature and structural characteristics of receptors ...
View Notes - phage normally infects cells to make more phage from BIOLOGY MCB2010 at Broward College. P PP P : Infect bacteria with ~10 of each phage per cell to insure that every cell has both kinds
Prospective Interdisciplinary PhD Projects. Tackling antibiotic resistance by measuring and modelling the uptake of viruses and antibiotics in single cell (co-supervised with Prof Krasimira Tsaneva-Atanasova). This interdisciplinary project will provide novel understanding on the biological mechanisms underlying antibiotic and phage uptake in gram-negative bacteria which is paramount for our battle against infectious diseases. In this project we aim to quantitate the accumulation of antibiotics and bacteriophage in gram negative species such as Escherichia coli and Pseudomonas aeruginosa, combining fluorescent drug derivatives, stained phage and single-bacterium imaging. These data will be rationalised by using a mathematical model that describes the temporal changes in antibiotic or phage concentration in single bacteria and will inform how phenotypic heterogeneity, in both the bacterial and phage populations, impacts on population and evolutionary dynamics. Taken together the information ...
1307 patients with suppurative bacterial infections caused by multidrug resistant bacteria of different species were treated with specific bacteriophages (BP). BP therapy was highly effective; full recovery was noted in 1123 cases (85.9%). In 134 cases (10.9%) transient improvement was observed and only in 50 cases (3.8%) BP treatment was found to be ineffective. The results confirm the high effectiveness of BP therapy in combating bacterial infections which do not respond to treatment with all available antibiotics ...
Bacteriophage is a live micro-organism, a natural enemy of bacteria. Canadian microbiologist Felix d Herelle proposed that bacteriophage might be applied to the control of bacterial diseases, however in the West this idea was not explored with the same enthusiasm as in the former Soviet Union and was eventually discarded with the arrival of antibiotics. Phage therapy is successfully used for the treatment of a wide spectrum of bacterial infections. Such experience has now become extremely important with the rapidly-increasing spread of antibiotic-resistant bacterial infections which are almost impossible to overcome these days. Phage therapy has been considered as an alternative to antibiotic-therapy and it is now attracting global interest. Most of the scientific works in phage therapy were published in Russian and are thus not easily available in the West. This fact inspired the authors to write a book based on the historical publications found in the library of the Eliava Institute. (Imprint: ...
Increasing resistance to antibiotics and market demands for clean label processes has led to increased focus on new strategies to control pathogenic bacteria in foods and animal production. Bacteriophages are among the top predators of bacteria in nature - ubiquitous in the environment yet also highly specific - making them attractive as antimicrobials. This webinar will cover some of the basic biology of phages, how they work and some considerations on initial product development.. Presenter:. Dr. Jason Gill joined the faculty of the Department of Animal Science as an Assistant Professor in 2013. Dr. Gills major research focus is the biology and application of the viruses of bacteria, called bacteriophages or simply phages. As natural predators of bacteria, phages are attractive agents for the control of pathogenic bacteria in humans, animals, and foods. Research in Dr. Gills lab encompasses phage genomics, basic phage biology and the applications of phages in real-world settings against ...
View DNA Rearrangements from BIOLOGY MCB2010 at Broward College. Examples : Integration of bacteriophage DNA into host bacterial chromosome Immunoglobulin and T Cell Receptor genes DNA rearrangements
TY - JOUR. T1 - Efficient in vitro synthesis of biologically active RNA and RNA hybridization probes from plasmids containing a bacteriophage SP6 promoter. AU - Melton, D. A.. AU - Krieg, P. A.. AU - Rebagliati, M. R.. AU - Maniatis, T.. AU - Zinn, K.. AU - Green, M. R.. N1 - Funding Information: ACKNOWLEDGEMENTS We are grateful to D. Ward and B. Mierendorf for sharing their unpublished results. We thank K. Breakey for help in preparing figures. P. K. acknowledges support from the Fogarty International Fellowship program. M.R. is grateful for support from an NSF Predoctoral Fellowship. This work was supported by a grant from the NIH to T.M. and grants from the NIH and the Chicago Community Trust/Searle Scholars Program to D.M. Copyright: Copyright 2010 Elsevier B.V., All rights reserved.. PY - 1984/9/25. Y1 - 1984/9/25. N2 - A simple and efficient method for synthesizing pure single stranded RNAs of virtually any structure is described. This in vitro transcription system is based on the ...
Middleton C.A., J.L. Pate. 1976. Isolation and partial characterization of some new bacteriophages active against Asticcacaulis strains. Int. J. Syst. Bacteriol. 26: 269-277. ...
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The number of successful propagations/isolations of soil-borne bacteriophages is small in comparison to the number of bacteriophages observed by microscopy (great plaque count anomaly). As one...
Most human microbiota studies focus on bacteria inhabiting body surfaces, but these surfaces also are home to large populations of viruses. Many are bacteriophages, and their role in driving bacterial diversity is difficult to decipher without the use of in vitro ecosystems that can reproduce human microbial communities. We used chemostat culture systems known to harbor diverse fecal bacteria to decipher whether these cultures also are home to phage communities. We found that there are vast viral communities inhabiting these ecosystems, with estimated concentrations similar to those found in human feces. The viral communities are composed entirely of bacteriophages and likely contain both temperate and lytic phages based on their similarities to other known phages. We examined the cultured phage communities at five separate time points over 24 days and found that they were highly individual-specific, suggesting that much of the subject-specificity found in human viromes also is captured by this culture
The world is in the midst of a global superbug crisis. Antibiotic resistance has been found in numerous common bacterial infections, including tuberculosis, gonorrhoea and salmonellosis, making them difficult - if not impossible - to treat. Were on the cusp of a post-antibiotic era, where there are fewer treatment options for such antibiotic-resistant strains. Given estimates that antibiotic resistance will cause 10 million deaths a year by 2050, finding new methods for treating harmful infections is essential.. Strange as it might sound, viruses might be one possible alternative to antibiotics for treating bacterial infections. Bacteriophages (also known as phages) are viruses that infect bacteria.. Theyre estimated to be the most abundant organisms on Earth, with probably more than 1031 bacteriophages on the planet. They can survive in many environments, including deep sea trenches and the human gut. While phages are efficient killers of bacteria, they dont infect human cells and are ...
For whoever is qualified to answer me: I would like to know what specific Bacteriophages will attack Salmonella enteriditis. I am working on the potential antibacterial affects of phages against human pathogens. Any responses will be greately appreciated Thank you George T ...
Sabella has two different morphologies: some of the plaques are 0.1 cm in diameter, while others are 0.15 cm in diameter. This notable difference was tested multiple times, so the phage population of this lytic phage is consistent and contains two morphologies. All the plaques are clear and round with smooth edges ...
- SS2378646 A bacteriophage, comprising a proteic envelope (called capsid), which contains its nucleic acid (DNA or RNA), and a tail. The tail includes a collar (covered with contractile proteins for the most elaborated bacteriophages, such as the T2 and T4 phages) and ending with tail fibers enabling it to attach to the bacteria it infects.
A type of single-stranded DNA bacteriophage ( virus which infects bacteria ) that has a capsid which is long and thin, like a filament. Examples include the viruses F1 and M13 ...
http://www.ibioseminars.org/ Bacteriophage, viruses that specifically infect bacteria, are, by far, the majority of all biological entities in the biosphere....
There are many similarities in the replication mechanisms employed by bacteriophage λ and its host E. coli(for reviews, see Bramhill and Kornberg, 1988, Keppel et al., 1988, and McMacken et al.,...
While I can find a wealth of information on the theory of bacteriophages, I cant seem to find anything useful on their actual use(though I hear theyre used with frequency in Georgia[the country]). Ever since Ive known what they are, Ive thought that bacteriophages would be perfect to treat acne. When I saw this article, I was slightly hopeful that I might find a clinical trial(at clinicaltrials.gov), but I found exactly bupkis ...
While I can find a wealth of information on the theory of bacteriophages, I cant seem to find anything useful on their actual use(though I hear theyre used with frequency in Georgia[the country]). Ever since Ive known what they are, Ive thought that bacteriophages would be perfect to treat acne. When I saw this article, I was slightly hopeful that I might find a clinical trial(at clinicaltrials.gov), but I found exactly bupkis ...
Help your students understand the connection between bacteriophages and human disease. This scholarly overview explores how bacteriophages have helped and hindered humans in their quest to overcome certain diseases. Use it as assigned reading or to kick off a classroom discussion.
This sequence contains a string of Gs starting at 32032 bp, consensus determined to contain 13 Gs. Some of the phage population may contain anywhere from 8-14 Gs at this location ...
Viruses are parasitic infectious agents with a nanoscale shell, known as the capsid, that encapsulates the genomic material. Most bacteriophage viruses invade bacteria by transferring their genome inside the host cell while leaving the capsid outside. Thus, the foremost event of bacteriophage infection is the ejection of genomic material into the host bacterium after the virus has recognized and bound to surface receptor sites. How ejection is triggered is yet unknown. We show, by manipulating individual mature T7 phage particles, that tapping the capsid wall with an oscillating atomic-force-microscope cantilever triggers rapid DNA ejection via the tail complex. Triggering rate increases exponentially as a function of force, hence follows transition-state theory, across an activation barrier of 23 kcal/mol at 1.2 nm along the reaction coordinate. The conformation of the ejected DNA molecule revealed that it had been exposed to a propulsive force. This force, arising from intra-capsid pressure, assists
Generalized transduction is commonly used to move transposon-induced mutations among bacterial strains by selecting for inheritance of a transposonencoded resistance determinant. Although complete cotransduction of the resistance determinant and the chromosomal mutation might be expected, it is often found that when Tn5(Kan) insertion mutations are transduced by bacteriophage P1 most of the nonmutant kanamycin-resistant transductants are due to specialized transduction of Tn5. Such P1::Tn5 specialized transducing phage are not found when a mutant Tn5 element lacking a functional transposase is employed.. ...
Froman, S., W. Drake, E. Bogen. 1954. Bacteriophage active against virulent Mycobacterium tuberculosis. I. Isolation and activity. Amer. J. Publ. Health. 44: 1326-1333. ...
Answer. Viruses are sub6microscopic infectious agents that can infect all living organisms. A virus consists of genetic material surrounded by a protein coat. The genetic material may be present in the form of DNA or RNA.. Most of the viruses, infecting plants, have single stranded RNA as genetic material. On the other hand, the viruses infecting animals have single or double stranded RNA or double stranded DNA. Bacteriophages or viruses infecting bacteria mostly have double stranded DNA. Their protein coat called capsid is made up of capsomere subunits. These capsomeres are arranged in helical or polyhedral geometric forms. ...
The prevalence of pathogenic bacteria acquiring multidrug antibiotic resistance is a global health threat to mankind. This has motivated a renewed interest in developing alternatives to conventional antibiotics including bacteriophages (viruses) as therapeutic agents. The bacterium Clostridium difficile causes colon infection and is particularly difficult to treat with existing antibiotics; phage therapy may offer a viable alternative. The punitive environment within the gastrointestinal tract can inactivate orally delivered phages. C. difficile specific bacteriophage, myovirus CDKM9 was encapsulated in a pH responsive polymer (Eudragit® S100 with and without alginate) using a flow focussing glass microcapillary device. Highly monodispersed core-shell microparticles containing phages trapped within the particle core were produced by in situ polymer curing using 4-aminobenzoic acid dissolved in the oil phase. The size of the generated microparticles could be precisely controlled in the range 80 ...
Phage therapy or viral phage therapy is the therapeutic use of bacteriophages to treat pathogenic bacterial infections. Phage therapy has many potential applications in human medicine as well as dentistry, veterinary science, and agriculture. If the target host of a phage therapy treatment is not an animal, the term biocontrol (as in phage-mediated biocontrol of bacteria) is usually employed, rather than phage therapy. Bacteriophages are much more specific than antibiotics. They are typically harmless not only to the host organism, but also to other beneficial bacteria, such as the gut flora, reducing the chances of opportunistic infections. They have a high therapeutic index, that is, phage therapy would be expected to give rise to few side effects. Because phages replicate in vivo, a smaller effective dose can be used. On the other hand, this specificity is also a disadvantage: a phage will only kill a bacterium if it is a match to the specific strain. Consequently, phage mixtures are ...
An efficient heat-inducible Bacillus subtilis bacteriophage 105 expression and secretion system for the production of the Streptomyces clavuligerus beta-lactama
Bacteriophages, the viruses that infect bacteria, are the most abundant biological entities in the biosphere and play a key role in global biogeochemical cycling. All T4-type bacteriophage isolates tested so far have a conserved genetic module that encodes the virion components including gene 23 (g23), the major capsid protein. Molecular analysis of the g23 sequence revealed a remarkable level of diversity of T4-type bacteriophages isolated from rice straw and surface soil in a Japanese rice field. It was found that g23 sequences obtained from the rice field were quite distinctive from those obtained in marine environments. Phylogenetic analysis showed that most of these g23 sequences belonged to two novel subgroups of T4-type bacteriophages, although some of them were related to well-studied subgroups of T4-type bacteriophages, such as marine cyanophage isolates of exoT-evens. ...
Urinary tract infections (UTIs) are among the most prevalent microbial diseases and their financial burden on society is substantial. In the context of increasing antibiotic resistance, finding alternative treatments for UTIs is a top priority. We aimed to determine whether intravesical bacteriophage therapy with a commercial bacteriophage cocktail is effective in treating UTI.. Intravesical bacteriophage therapy was non-inferior to standard-of-care antibiotic treatment, but was not superior to placebo bladder irrigation, in terms of efficacy or safety in treating UTIs in patients undergoing TURP. Moreover, the bacteriophage safety profile seems to be favourable. Although bacteriophages are not yet a recognised or approved treatment option for UTIs, this trial provides new insight to optimise the design of further large-scale clinical studies to define the role of bacteriophages in UTI treatment.. ...
TY - JOUR. T1 - Size exclusion-based purification and PCR-based quantitation of MS2 bacteriophage particles for environmental applications. AU - Farkas, Kata. AU - Varsani, Arvind. AU - Marjoshi, Delphine. AU - Easingwood, Richard. AU - McGill, Erin. AU - Pang, Liping. N1 - Funding Information: This work was funded by the Royal Society of New Zealand (Marsden Grant ESR-1001 ). D. Marjoshi was supported by a summer scholarship provided by the Royal Society of New Zealand and the University of Canterbury, New Zealand. The authors thank the following people for their support and assistance: R. Fredericks (University of Canterbury, New Zealand), W. Williamson and M. Mackenzie (Institute of Environmental Science & Research Ltd, New Zealand). PY - 2015/3/1. Y1 - 2015/3/1. N2 - MS2 bacteriophage is the most commonly used surrogate for pathogenic viruses in laboratory and field studies. In order to determine the number of infectious viral particles in samples, the use of accurate quantitation methods is ...
Summary Tris(hydroxymethyl)aminomethane (tris) inactivates Lactobacillus lactis bacteriophage LL-H in vitro. The inactivation is caused by DNA ejection. This effect occurs in tris-HCl buffer only. Both pH and temperature affect the sensitivity of the phage to the tris treatment. The divalent cation Mg2+ prevented the inactivating effect of tris at concentrations about 103-fold lower than for the monovalent cation K+.
Abstract: Bacteriophages have been proposed as specific alternative for chemotherapy against multidrug resistant bacterial infections. The aim of the present study was the isolation and purification of bacteriophages from sewage, which were effective against multidrug resistant bacterial isolates and detection of their morphological characteristics. Sewage and clinical samples were used for the isolation of antibiotic resistant pathogenic bacteria. The bacteriophages were isolated and purified from sewage samples by overlay cultures of the isolated bacteria after centrifugation and filtration procedures. Three isolates of the most multidrug resistant Escherichia coli, Klebsiella pneumonia and Pseudomonas aeruginosa selected for bacteriophage isolation. Most of the isolates were resistant to different classes of antibiotics in the aminoglycosides, cephalosporins, macrolides, tetracyclines and β-lactam antibiotic groups. The isolated bacteriophges showed different plaque morphologies on the ...
The bacteriophage MS2 is an icosahedral, positive-sense single-stranded RNA virus that infects the bacterium Escherichia coli and other members of the Enterobacteriaceae. MS2 is a member of a family of closely related bacterial viruses that includes bacteriophage f2, bacteriophage Qβ, R17, and GA. In 1961, MS2 was isolated by Alvin John Clark and recognized as an RNA-containing phage very similar to bacteriophage f2. In 1976, the MS2 genome was the first genome to be completely sequenced. This was accomplished by Walter Fiers and his team, building upon their earlier milestone in 1972 of the first gene to be completely sequenced, the MS2 coat protein. These sequences were determined at the RNA level, whereas the next landmark achievement, the sequence of the bacteriophage ΦX174 genome in 1977, was determined using DNA. The first effort at a statistical analysis of the MS2 genome was a search for patterns in the nucleotide sequence. Several non-coding sequences were identified, however at the ...
The aim of this work was to verify the possibility of applying affinity chromatography in bacteriophage purification, from the perspective of therapeutic purposes. Elution profiles of phages modified with specific affinity motifs (Figures 3,4,5 and 6) show substantially higher phage concentration in elution fractions compared to final washing samples. This indicates binding of modified phages to the affinity resins and effective elution with standard competitive agents. Thus, affinity tags can be successfully incorporated into the T4 phage capsid by the in vivo phage display technique and they strongly elevate bacteriophage affinity to a specific resin. Non-specific binding was also observed: unmodified phages or those modified with the non-specific tag were eluted with the titre 104-105 pfu/ml. Nevertheless, the unspecific binding is 102-105 times weaker than the specific one and importantly it does not interfere with the aim of preparation of purified anti-bacterial active bacteriophages for ...
Phage therapy has also proven to be an effective therapeutic tool in fighting pathogenic strains of Escherichia coli, particularly in preventing the development of colibacillosis, which initially develops in the respiratory tract and air sacs and then takes the form of sepsis, causing considerable mortality in poultry.. Phage suspensions applied directly to the air sac in 3-day-old birds in a range of titres from 106 to 103 PFU to treat E. coli infections substantially reduced mortality rates to 5% and 25%, respectively. Similar results were obtained after inoculation of a bacteriophage suspension in the drinking water of birds at 1 week of age (103 or 104 PFU of bacteriophages per mL) followed by air sac challenge with 103 CFU of E. coli phages. Mortality was decreased to 25% and 5%, respectively. No mortality was observed in chickens treated with 108 PFU of an E. coli bacteriophage mixture [38]. Bacteriophages have also been shown to be highly effective in treating sepsis and meningitis in ...
Bacterial urinary tract infections (UTIs) are very frequent, especially in patients with neurogenic lower urinary tract dysfunction (NLUTD). The steady increase in antibiotic resistance among causative bacteria prompts the search for highly effective therapeutic alternatives with little or no side effects. Bacteriophages - obligate intracellular viruses that solely infect and kill bacteria - are promising tools for treating bacterial infections and have been used for this purpose for almost a century. Recent clinical studies using bacteriophage therapy for UTIs showed encouraging results. In particular, patients with recurrent UTIs, such as individuals with NLUTD who rely on assisted bladder emptying, might benefit from this treatment method. However, bacteriophages are not yet a panacea. More high-quality basic and clinical research on bacteriophage therapy is needed to answer questions on the use of this therapeutic option and its potential to provide a solution to the global threat of ...
TY - PAT. T1 - SELECTION SYSTEM FOR PHAGEMIDS USING PROTEOLYTICALLY SENSITIVE HELPER PHAGE. AU - Lutz, Riechmann. AU - Peter, Kristensen. AU - Jean-Luc, Jestin. AU - Gregory Paul, Winter. AU - Lutz , Riechmann. AU - Peter , Kristensen. AU - Jean-Luc , Jestin. AU - Gregory Paul , Winter. PY - 2003/3/26. Y1 - 2003/3/26. N2 - A method for effecting helper phage rescue of a phagemid comprising a fusion polypeptide to form progeny bacteriophage wherein (a) the helper phage encodes a viral coat protein comprising a protease sensitive cleavage site (b) the phagemid comprises a fusion polypeptide (c) the progeny phage are exposed to a protease capable of cleaving the proteolytically cleavable site such that the cleavage of the protein derived from the helper phage impairs its ability to mediate infection and (d) the progeny are propagated by infection. The helper phage has the protease sensitive site within p3 coat protein and is the filamentous bacteriophage M13, fd or a related species.. AB - A method ...
Regular use of phage therapy occurs primarily in the Republic of Georgia, due to the presence of the Eliava Institute, which has research phage therapy since the 1920s. However, synthetic biology has enabled entirely new approaches to phage therapy, such as engineering new abilities into the phage. One such ability is the degradation of the extracellular polysaccharides (EPS) produced by bacteria during infections[2]. Production of the EPS results in a biofilm, which protects the bacteria within from external harm, such as antibiotics and bacteriophages, limiting the damage to the cells on the surface. To break through this barrier, researches inserted the gene for DspB, an enzyme that degrades one of the key components of EPS. After bacteria on the surface of the biofilm are infected, they produce DspB along with new phage. After the cells lyse, the DspB can degrade the EPS, which exposes more bacteria to infection. One concern of phage therapy is the rapid lysing of pathogenic cells which may ...
Bacteriophages are an important repository of genetic diversity. As one of the major constituents of terrestrial biomass, they exert profound effects on the earths ecology and microbial evolution by mediating horizontal gene transfer between bacteria and controlling their growth. Only limited genomic sequence data are currently available for phages but even this reveals an overwhelming diversity in their gene sequences and genomes. The contribution of the T4-like phages to this overall phage diversity is difficult to assess, since only a few examples of complete genome sequence exist for these phages. Our analysis of five T4-like genomes represents half of the known T4-like genomes in GenBank. Here, we have examined in detail the genetic diversity of the genomes of five relatives of bacteriophage T4: the Escherichia coli phages RB43, RB49 and RB69, the Aeromonas salmonicida phage 44RR2.8t (or 44RR) and the Aeromonas hydrophila phage Aeh1. Our data define a core set of conserved genes common to these
0036] Disclosed methods may be utilized to simultaneously detect a plurality of different pathogens. For instance, a plurality of recombinant bacteriophages specific for different bacterial pathogens may be located at a potential infection site or in an in vitro environment in which the pathogenic bacteria may exist. The recombinant bacteriophages may be engineered to encode for the same detectable markers or for different detectable markers, as desired. For instance, a plurality of different phages may all encode the same detectable marker. Upon detection of the marker, a medical professional may be alerted to the presence of a pathogen at the site of interest, signaling the need for further investigation to determine the specific bacteria involved. In another embodiment, different phages may encode different markers. According to this embodiment, determination of the characteristics of a detected signal may provide information regarding the specific bacteria involved in the infection. ...
Usually bacteriophages lyse their hosts following infection, however a few so-called temperate phage undergo lysogeny. In lysogeny, the bacteriophage integrates its genome into that of its host. The phage, then, is replicated each time the bacterial cell divides. In the lysogenic state, the bacteriophage can have considerable influence over host physiology ...
In the United States, billions of pounds of animal by-products are generated by the food processing industry every year. Hydrogen sulfide producing bacteria (SPB) can utilize the sulfur-containing proteins and amino acids in the raw animal materials destined for the rendering process to produce harmful hydrogen sulfide (H2S) gas rapidly under the ambient conditions, resulting in hazardous working environments and inferior quality of finished products. In this study, the application of bacteriophage was explored as an effective solution for the elimination of H2S production in the rendering industry. The objectives of this study were to: 1) isolate and characterize strains of SPB and their specific bacteriophages, 2) to develop and optimize a bacteriophage cocktail specific for SPB, 3) to reduce the SPB population and H2S production in raw animal materials by administering phage cocktail under both laboratory condition and greenhouse environment. Twenty two meat, chicken offal and feather samples
0040]Purification of the bacteriophages can be obtained by known methods. As an example, the culture medium can be filtered through a very small pore size filter to retain the targeted contaminant--i.e., the bacteria--, and permit the smaller bacteriophage to pass through. Typically, a filter having a pore size in the range of from about 0.01 to about 1 μm can be used, preferably from about 0.1 to about 0.5 μm, and more preferably from about 0.2 to about 0.4 μm. The culture medium can be also purified from bacterial debris and endotoxins by dialysis using the largest pore membrane that retains bacteriophages, where the membrane preferably has a molecular cut-off of approximately 104 to about 107 daltons, preferably within the range of from about 105 to about 106 daltons. Many other suitable methods can be performed as disclosed for example in US 2001/0026795; US 2002/0001590; U.S. Pat. No. 6,121,036; U.S. Pat. No. 6,399,097; U.S. Pat. No. 6,406,692; U.S. Pat. No. 6,423,299; and WO 02/07742, ...
Bacteria and archaea have evolved an adaptive, heritable immune system that recognizes and protects against viruses or plasmids. This system, known as the CRISPR/Cas system, allows the host to recognize and incorporate short foreign DNA or RNA sequences, called spacers into its CRISPR system. Spacers in the CRISPR system provide a record of the history of bacteria and phage coevolution. We use a physical model to study the dynamics of this coevolution as it evolves stochastically over time. We focus on the impact of mutation and recombination on the evolution and evasion of bacteria and phages. We discuss the effect of different spacer deletion mechanisms on the coevolutionary dynamics. We make predictions about bacteria and phage population growth, spacer diversity within the CRISPR locus, and spacer protection against the phage population. An important feature of this coevolution is the multiple loci in the phages from which CRISPR may sample genetic material. We construct a model with ...
Summary Three newly isolated strains of Streptomyces phages have been examined by electron microscopy using the negative-staining technique. These phages have polyhedral heads and noncontractile tails ending in a clearly distinct fixation structure. They differ in their dimensions, head outline, flexibility of the tail and type of fixation plate. Some of their characteristics are new in the group of actinophages but correspond to known structures in other phage groups.
Knowledge of phage-host interactions at a fundamental level is central to the design of rational strategies for the development of phage-resistant strains that may be applied in industrial settings. Phages infecting lactic acid bacteria, in particular Lactococcus lactis and Streptococcus thermophilus, negatively impact on dairy fermentation processes with serious economic implications. In recent years a wealth of information on structural protein assembly and topology has become available relating to phages infecting Escherichia coli, Bacillus subtilis and Lactococcus lactis, which act as models for structural analyses of dairy phages. In this review, we explore the role of model tailed phages, such as T4 and SPP1, in advancing our knowledge regarding interactions between dairy phages and their hosts. Furthermore, the potential of currently investigated dairy phages to in turn serve as model systems for this particular group of phages is discussed.
Since the advent of antibiotics, both the health care and agriculture sectors have relied heavily on them to control bacterial pathogens. However, increasing levels of antibiotic resistance have reduced the efficacy of many current therapies, prompting legislation that has reduced the use of antibiotics in animals. This has led researchers to seek fresh ideas. Bacteriophage therapy is one old idea undergoing a renaissance, with the potential to resolve the antibiotic predicament we find ourselves in today. Lytic bacteriophages are viruses that attach to specific bacterial surface receptors, inject their DNA, and express genes that lead to the synthesis of new phages. The process ends with the programmed lysis (death) of the host and the release of dozens or hundreds of new phages. The use of phages as antimicrobial agents has a number of advantages over other methods. Phages are highly specific allowing for the removal of the targeted microorganisms from a mixed population. Unlike antibiotics ...
Bacterial viruses, or phage, are key members of natural microbial communities. Yet much research on bacterial-phage interactions has been conducted in liquid cultures involving single bacterial strains. Here we explored how bacterial diversity affects the success of lytic phage in structured communities. We infected a sensitive Pseudomonas aeruginosa strain PAO1 with a lytic phage Pseudomonas 352 in the presence versus absence of an insensitive P. aeruginosa strain PA14, in liquid culture versus colonies on agar. We found that both in liquid and in colonies, inter-strain competition reduced resistance evolution in the susceptible strain and decreased phage population size. However, while all sensitive bacteria died in liquid, bacteria in colonies could remain sensitive yet escape phage infection, due mainly to reduced growth in colony centers. In sum, spatial structure can protect bacteria against phage infection, while the presence of competing strains reduces the evolution of resista
Phage therapy is a medical approach for the treatment of bacterial infectious diseases which makes use of the natural ability of some viruses, known as bacteriophages, to kill specific bacteria that they recognize. Phage therapy was first proposed nearly a century ago at the Institut Pasteur by the French-Canadian scientist Félix dHerelle. Although the technique was initially used worldwide, from the 1940s onwards it was particularly developed in Eastern Europe, while Western countries gradually lost interest in the approach and preferred to focus their attention on antibiotics, thought to be more promising. Medical use of phage therapy is currently hindered by the viral nature of this antibacterial treatment and the lack of precise knowledge about how bacteriophages work.. However, given the rise in bacterial resistance to antibiotics and the worrying prospect of a potential therapeutic impasse, scientists are once again beginning to explore the possibilities of bacteriophages. This field has ...
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Phage therapy became very popular throughout the world in the early 20th century to treat a wide range of diseases caused by a variety of bacterial pathogens. After the discovery and production of penicillin for use during World War II, phage therapy fell out of favor in many western countries, particularly the US.. The phage therapy cocktails used in the past didnt always work and some of that had to do with phage strain selection and bacteria developing resistance to them. Today, though the use of synthetic genomics techniques and tools, standardized cocktails of phage can be rapidly and efficiently engineered to be more clinically effective than traditional phage cocktails created by mixing phage isolated from sewage.. Through their work, the JCVI team believes novel phage products can be developed that could lead to improved prevention and treatment for MDRO infections where few treatment options remain due to the spread of multidrug-resistance. Potential treatments would include topical ...
TY - JOUR. T1 - Bacteriophage lambda-based expression vectors. AU - Christensen, A. C.. PY - 2001/6/28. Y1 - 2001/6/28. N2 - Bacteriophage lambda has been in use as a cloning vector for over 25 years, and has been used extensively as an expression vector. The efficiency of packaging and infection, and the simplicity of plaque screening are advantages of lambda as a cloning vector. A number of ingenious modifications help overcome the disadvantages associated with its mode of growth and its size. Some lambda vectors have been designed to be readily converted into plasmids or phagemids, and there are a variety of promoters and fusions that can be used to drive expression of foreign genes. Screening lambda libraries with antibodies or ligands is a powerful way of identifying novel genes.. AB - Bacteriophage lambda has been in use as a cloning vector for over 25 years, and has been used extensively as an expression vector. The efficiency of packaging and infection, and the simplicity of plaque ...
We present a CRISPR-Cas based technique for deleting genes from the T7 bacteriophage genome. A DNA fragment encoding homologous arms to the target gene to be deleted is first cloned into a plasmid. The T7 phage is then propagated in Escherichia coli harboring this plasmid. During this propagation, some phage genomes undergo homologous recombination with the plasmid, thus deleting the targeted gene. To select for these genomes, the CRISPR-Cas system is used to cleave non-edited genomes, enabling isolation of the desired recombinant phages. This protocol allows seamless deletion of desired genes in a T7 phage, and can be expanded to other phages and other types of genetic manipulations as well.
Summary/Abstract: A fundamental, clinical and scientific concern is how lytic bacteriophage, as well as antibiotics, impact diagnostic positivity. Cholera was chosen as a model disease to investigate this important question because cholera outbreaks enable large enrollment, field methods are well established, and the predatory relationship between lytic bacteriophage and the etiologic agent Vibrio cholerae share commonalities across bacterial taxa. Patients with diarrheal disease were enrolled at two remote hospitals in Bangladesh. Diagnostic performance was assessed as a function of lytic bacteriophage detection and exposure to the first-line antibiotic azithromycin detected in stool samples by mass spectrometry. Among diarrheal samples positive by nanoliter quantitative PCR for V. cholerae (n=78/849), the odds that a rapid diagnostic test (RDT) or qPCR was positive was reduced by 89% (OR 0.108; 95%CI 0.002-0.872) and 87% (OR 0.130; 95%CI 0.022-0.649) when lytic bacteriophage were detected, ...
Phage Therapy and Phage Resistance scheduled on March 02-03, 2020 in March 2020 in Rio de Janeiro is for the researchers, scientists, scholars, engineers, academic, scientific and university practitioners to present research activities that might want to attend events, meetings, seminars, congresses, workshops, summit, and symposiums.
This issue profiles a bacteriophage that aids efforts to destroy Enterococcus Faecalis bacteria, preventing salmonellosis through the usage of lytic bacteriophages, and development of multiple phage therapy products for infectious diseases .
Bacteriophages are viruses that infect specific bacterial hosts in order to grow and replicate. Because bacteriophages are miniscule in size, it is not possible to obtain images of the structural features using light microscopy. Transmission electron microscopy (TEM) is a useful technique to view images with higher resolution and magnification using electrons to illuminate the subject. This technique allows for clear visualization of bacteriophage structural features, including the head, capsid, and tail. Bacteriophages isolated from infections of the bacterial host Rhodobacter capsulatus, which include RcTitan, RcOceanus, RcSpartan, RcRhea, RcSaxon, and RcCronus, were examined. In order to obtain contrast, new lysates of each phage were placed on a formvar coated 200-mesh grid and stained with uranyl acetate. The negative stain from uranyl acetate allowed for high contrast, as the background is stained, while the phage is not and thus visible. Bacteriophage morphology, such as head sizes and tail
For genomic DNA extraction, bacteriophage SfΦ01 was inoculated to S. flexneri grown in R2A medium and incubated overnight at 37°C. Bacterial cells were removed by centrifugation and filtration with a 0.45-μm-pore-size filter. Bacteriophage particles were concentrated using the Centricon Plus-70 filter (Merck Millipore), and 160 μl of bacteriophage concentrate was mixed with 20 μl of DNase I (Promega) to digest free DNA. Bacteriophage genomic DNA was extracted from the resultant sample using the PowerBiofilm DNA isolation kit (Mo Bio Laboratories). Sequencing libraries were prepared using the TruSeq PCR-free library prep kit (Illumina) with an insert fragment size of ca. 350 bp and paired-end sequenced by using the MiSeq platform (Illumina) with v2 chemistry (250 cycles). The sequencing reads (541,594 reads each for forward and reverse sequencing reactions) were assembled de novo by using the SPAdes v. 3.12 program (10). The genome assembly depth (coverage) was 1,618. Genes were predicted by ...
Caspar and Klug (50) had predicted that, for each of the covalently identical subunits that compose the surface of a virus to have identical environments, it would require that the subunits are organized into an hexagonal array. An icosahedron is formed by substituting a pentagon of subunits for a hexagon of subunits at regular positions. This would then allow each subunit to have at least a quasi-equivalent environment. The total size of the assembly is determined by where the pentamers replace hexamers. This prediction has been found to be true in a large variety of viruses with T numbers varying from 1 for the smallest viruses such a parvoviruses (51) and the ΦX174 bacteriophage (52) to very large dsDNA viruses with T numbers of 169 [PBCV-1 (53⇓-55)] and 972 ≤ T ≤ 1,200 [Mimivirus (56)]. Here we have determined the structure of a virus with a T=13 lattice, which makes it possible to examine how the assembly process has introduced pentamers at specific positions in the hexagonal ...
Further, to address the critical question of whether adding spacers provides novel phage resistance, we replaced the CRISPR1 locus of strain WTΦ2972+S4 with a version containing only spacers S1 and S2 (12) and tested whether the phage sensitivity was affected. Remarkably, the resulting strain WTΦ2972+S4::pS1S2 gained resistance to phage 858, which suggested that these two spacers have the ability to provide phage resistance de novo (Fig. 3). Altogether, these observed modifications establish the link between the CRISPR spacer content and phage resistance.. In the process of generating strain WTΦ858+S1S2ΔCRISPR1, we created WTΦ858+S1S2::pR, a variant that contains the integration vector with a single repeat inserted between the cas genes and the native CRISPR1 locus (Fig. 3). Unexpectedly, strain WTΦ858+S1S2::pR was sensitive to phage 858, although spacers S1 and S2 remained on the chromosome (Fig. 3). Similarly, the WTΦ2972+S4::pS1S2 construct lost the resistance to phage 2972, although ...
Bacteriophages were first described by Frederick Twort in 1915 as agents that destroyed bacteria, leaving small areas of destruction (plaques) on bacterial lawns. It is now one hundred years later and we have made great advances both in our understanding of bacteriophage biology and how to use these viruses as tools to understand basic, general principles of biology including DNA being the hereditary material of life. Because 2015 was one hundred years following the first description of phages, it has been termed the year of the phage by many scientists. Not only does this year bear symbolic importance, but it actually marks some important advances in the field of phage therapy. Because we are nearing the end of the year of the phage, I thought it would be appropriate to briefly go over some of the advances I thought stood out the most ...
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Zimecki and colleagues describe the benefits of combined action of lactoferrin and phages in the treatment of infection of Escherichia coli and S. aureus in mice (12). Lactoferrin (LF) is a protein found in the secretory fluids of mammals and the secondary granules of neutrophils, and exhibits both antibacterial and anti-inflammatory actions. It has also been shown to enhance neutrophil production. In the experiment, mice were injected with E. coli and S. aureus, while the E. coli and S. aureus specific bacteriophages were administered intraperitoneally or orally one hour after bacteria injection. Lactoferrin was injected intravenously 24 hours before infection. The results showed that both oral and intraperritoneal phage administration proved effective in reducing numbers of bacteria in the liver, but the combined action of bacteriophages and LF produced a significant additive effect.. Fischetti and colleagues studied the antibacterial effect of bacteriophage lysins in various types of ...
The next step in dHerelles studies was to try and treat dysentery with his newly discovered bacteriophages. The study was conducted in 1919 in Paris after dHerelle proved the safety of his bacteriophages by having himself and all of the clinical staff involved as the first to ingest the bacteriophage preparation the day before! You can almost hear the conversation the next day...we survived the night so lets give it to a patient (wasnt experimental medicine great in those days...for those that survived)! The preparation was then given to a 12 year old boy who was dying from dysentery and within a day he was much improved and a few days later he was cured. Further patients were successfully treated and dHerelle was so convinced of his findings that he subsequently went on to treat thousands of patients with cholera and bubonic plague in India with various new bacteriophage preparations. Gosh, there seems there might be something exciting in this! However, dHerelle is also historically ...
Bacteriophage are viruses that infect bacteria. They were discovered independently by Frederick W. Twort in England in 1915 and by Felix d Herelle
Using continuous reaction norms to characterize adaptive responses to temperature, the researchers reexamined a recent study that linked rapid adaptation to specific genetic changes. The study, by Holder and Bull, showed that phage populations quickly evolved higher growth rates at higher temperatures. But, Knies et al. explain, these growth rates were correlated with just one temperature point the optimal temperature for the ancestral populations (used at the beginning of the experiment). Knies et al. reexamined phage thermal adaptation by measuring growth rate over a wider range of temperatures, then used a recently developed statistical method to identify the biological determinants of the shifts in the reaction norm shapes, quantify their relative contributions, and identify the genetic basis of the adaptations ...
The increase of multi-resistant bacteria highlights that the golden era of antibiotics is ending and that alternative treatmentsare urgently needed. Phages have been historically used to treat bacterial infections prior to the discovery of antibiotics and have gained renewed interest in the past decade. Despite the advantages of phage therapy over traditional antibiotic usage, a number of concerns persist over their clinical application centring on their efficacy and safety. This thesis presents four papers that focus on the isolation and characterization of phages that target reference strains and drug-resistant strains of E. coli as well as their infection dynamics and kinetics. In Paper I, six of thirty isolated phages were selected to be characterized for their growth parameters and host range using two commonly used methods. The study showed that the host range (an important selection criteria for phages) of the phages can change based on the assessment method and that the lysis efficiency ...