Phage therapy: An alternative to antibiotics in the age of multi-drug resistance

The practice of phage therapy, which uses bacterial viruses(phages) to treat bacterial infections, has been around for almost a century. The universal decline in the effectiveness of antibiotics has generated renewed interest in revisiting this practice. Conventionally, phage therapy relies on the use of naturally-occurring phages to infect and lyse bacteria at the site of infection. Biotechnological advances have further expanded the repertoire of potential phage therapeutics to include novel strategies using bioengineered phages and purified phage lytic proteins. Current research on the use of phages and their lytic proteins against multidrug-resistant bacterial infections, suggests phage therapy has the potential to be used as either an alternative or a supplement to antibiotic treatments. Antibacterial therapies, whether phage-or antibiotic-based, each have relative advantages and disadvantages; accordingly, many considerations must be taken into account when designing novel therapeutic approaches for preventing and treating bacterial infection. Although much about phages and human health is still being discovered, the time to take phage therapy serious again seems to be rapidly approaching.

A review on re-emerging bacteriophage therapy in the era of XDR

In the present medicine world antibiotic resistance is one of the key threats to universal health coverage.Researchers continue to work hard to combat this global health concern.Phage therapy,an age-old practice during the early twentieth century,was outshined by the discovery of antibiotics.With the advent of widespread antibiotic resistance,phage therapy has again redeemed itself as a potential alternative owing to its adeptness to target bacteria precisely.Limited side effects,the ability to migrate to different body organs,a distinct mode of action,and proliferation at the infection site,make phages a profitable candidate to replace conventional antibiotics.The progressive outcome of numerous in vitro studies and case reports has validated the clinical efficacy of phage therapy.The bright perspective of using phages to treat bacterial infections has fueled enormous medical research to exploit their potential as therapeutics.The gaps in the information about phages and the lack of consent for clinical trials is major hurdle for consideration of phage therapy.Crafting phage therapy as a reality in medicine requires a coordinated effort from different fraternities.With this review,we aim to emphasize the importance of phage therapy in modern medicine.This review explains their historical journey,basic phage biology,cross-talk with the host immunity,obstacles with phage therapy,and their possible remedies.Comprehensive data on the various significant clinical trials of phage therapy has been presented.We evaluated the efficacy of antibiotics and phage therapy in part and in combination,along with recent progress and future perspectives of phage therapy.

Selection of phages and conditions for the safe phage therapy against Pseudomonas aeruginosa infections

The emergence of multidrug-resistant bacterial pathogens forced us to consider the phage therapy as one of the possible alternative approaches to treatment. The purpose of this paper is to consider the conditions for the safe, long-term use of phage therapy against various infections caused by Pseudomonas aeruginosa. We describe the selection of the most suitable phages, their most effective combinations and some approaches for the rapid recognition of phages unsuitable for use in therapy. The benefi ts and disadvantages of the various different approaches to the preparation of phage mixtures are considered, together with the specifi c conditions that are required for the safe application of phage therapy in general hospitals and the possibilities for the development of personalized phage therapy.

Temperate Stutzerimonas Phage Encoding Toxin-Antitoxin System Genes Represents a Novel Genus

Stutzerimonas have been extensively studied due to their remarkable metabolic and physiological diversity.However,research on its phages is currently limited.In this study,we isolated a novel double-stranded DNA(dsDNA)phage,vB_SstM-PG1,from the marine environment that infects Stutzerimonas stutzeri G1.Its dsDNA genome is 37204 bp long with a G/C content of 64.14%and encodes 54 open reading frames.The phage possesses a tail packaging structure that is different from known Stutzerimonas stutzeri phages and exhibits structural protein characteristics similar to those of temperate phages.In addition,two genes of toxin-antitoxin system,including YdaS_antitoxin and HEPN_SAV_6107,were found in the vB_SstM-PG1 genome and play important roles in regulating host growth and metabolism.With phylogenetic tree and comparative genomic analysis,it has been determined that vB_SstM-PG1 is not closely related to any phages previously identified in the GenBank database.Instead,it has a connection with enigmatic,uncultured viruses.Specifically,the vB_SstM-PG1 virus exhibits an average nucleotide identity of over 70%with six uncultivated viruses identified in the IMG/VR v4 database.This significant finding has resulted in the identification of a novel viral genus known as Metabovirus.

Bacteriophages and their applications in the diagnosis and treatment of hepatitis B virus infection

Hepatitis B virus(HBV) infection is a major global health challenge leading to serious disorders such as cirrhosis and hepatocellular carcinoma. Currently, there exist various diagnostic and therapeutic approaches for HBV infection. However, prevalence and hazardous effects of chronic viral infection heighten the need to develop novel methodologies for the detection and treatment of this infection. Bacteriophages, viruses that specifically infect bacterial cells, with a long-established tradition in molecular biology and biotechnology have recently been introduced as novel tools for the prevention, diagnosis and treatment of HBV infection. Bacteriophages, due to tremendous genetic flexibility, represent potential to undergo a huge variety of surface modifications. This property has been the rationale behind introduction of phage display concept. This powerful approach, together with combinatorial chemistry, has shaped the concept of phage display libraries with diverse applications for the detection and therapy of HBV infection. This review aims to offer an insightful overview of the potential of bacteriophages in the development of helpful prophylactic(vaccine design), diagnostic and therapeutic strategies for HBV infection thereby providing new perspec-tives to the growing field of bacteriophage researches directing towards HBV infection.

用Phage88快速检测结核分枝杆菌

目的 建立一种特异性强、灵敏度高的致病性分枝杆菌的检测及药敏试验方法。方法 应用可表达荧光素酶的结核分枝杆菌噬菌体 Phage88,采用生物发光方法对不同细菌的发光反应和药敏试验进行检测。结果 Phage88特异地对各种分枝杆菌发光 ,对非分枝杆菌发光值很低 ,两者差异有显著性 ,不同的分枝杆菌发光值有差异 :卡介苗的发光值最高 ,结核杆菌的发光值最低 ;在含抗结核药物的培养基中 ,耐药结核杆菌的发光强度比非耐药结核杆菌强 ,其强度有明显差异。结论 用 Phage88噬菌体检测结核分枝杆菌是一种快速、敏感的检测和药敏试验方法。

Bacteriophages, revitalized after 100 years in the shadow of antibiotics

The year 2015 marks 100 years since Dr.Frederick Twort discovered the"filterable lytic factor",which was later independently discovered and named "bacteriophage" by Dr.Felix d’Herelle.On this memorable centennial,it is exciting to see a special issue published by Virologica Sinica on Phages and Therapy.In this issue,readers will not only fi nd that bacteriophage research is a

Phage lytic enzymes: a history

There are many recent studies regarding the efficacy of bacteriophage-related lytic enzymes: the enzymes of ‘bacteria-eaters' or viruses that infect bacteria. By degrading the cell wall of the targeted bacteria, these lytic enzymes have been shown to efficiently lyse Gram-positive bacteria without affecting normal flora and non-related bacteria. Recent studies have suggested approaches for lysing Gram-negative bacteria as well(Briersa Y, et al., 2014). These enzymes include: phage-lysozyme, endolysin, lysozyme, lysin, phage lysin, phage lytic enzymes, phageassociated enzymes, enzybiotics, muralysin, muramidase, virolysin and designations such as Ply, PAE and others. Bacteriophages are viruses that kill bacteria, do not contribute to antimicrobial resistance, are easy to develop, inexpensive to manufacture and safe for humans, animals and the environment. The current focus on lytic enzymes has been on their use as anti-infectives in humans and more recently in agricultural research models. The initial translational application of lytic enzymes, however, was not associated with treating or preventing a specifi c disease but rather as an extraction method to be incorporated in a rapid bacterial detection assay(Bernstein D, 1997).The current review traces the translational history of phage lytic enzymes–from their initial discovery in 1986 for the rapid detection of group A streptococcus in clinical specimens to evolving applications in the detection and prevention of disease in humans and in agriculture.

Bacteriophages as antimicrobial agents against major pathogens in swine： a review

In recent years, the development of antibiotic resistant bacteria has become a global concern which has prompted research into the development of alternative disease control strategies for the swine industry. Bacteriophages （viruses that infect bacteria） offer the prospect of a sustainable alternative approach against bacterial pathogens with the flexibility of being applied therapeutically or for biological control purposes. This paper reviews the use of phages as an antimicrobial strategy for controlling critical pathogens including Salmonella and Eschefich[a coli with an emphasis on the application of phages for improving performance and nutrient digestibility in swine operations as well as in controlling zoonotic human diseases by reducing the bacterial load spread from pork products to humans through the meat,

Bacteriophage Biocontrol Rescues Mice Bacteremic of Clinically Isolated Mastitis from Dairy Cows Associated with Methicillin-Resistant <i>Staphyloccocus aureus</i>

Methicillin-resistant Staphylococcus aureus (MRSA) is among the most alarming pathogens affecting both humans and the global bovine industry. The current control measures in hospitals and on farms for MRSA have proven to be inadequate leaving a need for new rapid control methods to curb MRSA infections in situ. New control measures for bacterial infection are widely sought, with particular interest in the applications for bacteriophages (phages) as a biocontrol or therapeutic agent. The current study uses a wild highly lytic phage isolated from cow’s milk taken from three farms in Baghdad, Iraq. The resulting phage was able to rescue 100% of the mice from a median lethal dose (LD50) or (1 × 108 CFU mL-1 per mouse) for MRSA wild isolates achieved when the phage: bacteria ratio was 100:1. Even when treatment was delayed for 6 h post lethal infection, to the point where all mice were moribund, 80% of them were rescued by a single injection of this phage preparation. Based on the current results, a comprehensive study is needed to guide further research on the MRSA phage as a biocontrol for MRSA mastitis in dairy cows to replace or reduce the use of antibiotics in animal husbandry.

噬菌体多肽phage20抗胃癌肝转移作用的实验研究

目的 鉴定选择性噬菌体多肽phage2 0是否具有抗胃癌肝高转移细胞XGC9811-L肝转移的作用。方法 采用胃浆膜下裸鼠原位接种转移模型 ,观察phage2 0对胃癌细胞XGC9811-L肝转移能力的影响。裸鼠随机分为实验组 (phage2 0孵育组 12只 ) ,对照组 (XGC9811-L组 12只、M13wt孵育组 12只 ) ,原位接种后 10天、5周解剖裸鼠 ,观察肝转移率、转移瘤的数目及原发瘤的体积。结果 在原位接种后 10天 ,各组未发现肝转移灶 ,接种后5周phage2 0孵育组、XGC9811-L未孵育组、M13孵育组肝转移率分别为 :2 0 % ,10 0 % ,80 % ;肝转移灶的数目为 0 ,9.5± 2 .8,7.1± 4 .71;原发瘤的体积为 0 .6 5± 0 .4 32 ,0 .5 2 8± 0 .2 96 ,0 .5 82± 0 .348。与对照组相比phage2 0孵育组的肝转移率和转移灶的数目明显减少 ,P <0 .0 5 ,但在原发瘤的体积方面 3者间无显著差别 P >0 .0 5。结论 phage2 0可抑制胃癌肝高转移潜能细胞XGC9811-L肝转移能力 ,但对其生长无影响。

Phage Display技术在抗体库中的应用现状

PhageDisplay技术是将外源蛋白通过与丝状噬菌体外壳蛋白融合而将外源蛋白表达于噬菌体颗粒的表面。该技术已被应用于噬菌体抗体库中，为单克隆抗体的制备及鼠单抗的人源化提供了一条有效的途径。它可以使人们在体外模拟体内抗体产生的过程，构建总抗体库，不经细胞融合，甚至不经免疫制备针对任何抗原的单克隆抗体。本文综述了该技术近年来在抗体库中的应用进展。

Effect of bacteriophage lysin on lysogens

Objective:To study the effect of phage lysin on the growth of lysogens.Methods:Sputum specimens processed by modified Petroff's method were respectively treated with phagebiotics in combination with lysin and lysin alone.The specimens were incubated at 37 ℃ for 4 days.At the end of day 1,2,3 and day 4,the specimens were streaked on blood agar plates and incubated at37 ℃ for 18-24 hours.The growth of normal flora observed after day 1 was considered as lysogens.Results:Sputum specimens treated with phagebiotics-lysin showed the growth of lysogens.When specimens treated with lysin alone,lysogen formation was avoided and normal flora was controlled.Conclusions:Lysin may have no effect on the growth of lysogens.

Progresses of mycobacteriophage-based Mycobacterium tuberculosis detection

Tuberculosis(TB)remains a major cause of morbidity and mortality worldwide,particularly in developing countries.A rapid and efficient method for TB diagnosis is indispensable to check the trend of tuberculosis expansion.The emergence of drug-resistant bacteria has increased the challenge of rapid drug resistance tests.Due to its high specificity and sensitivity,bacteriophage-based diagnosis is intensively pursued.In this review,we mainly described mycobacteriophage-based diagnosis in TB detection,especially two prevalent approaches:fluorescent reporter phage and phage amplified biologically assay(PhaB).The rationale of reporter phage is that phage carrying fluorescent genes can infect host bacteria specifically.Phage amplified biological assay based on the principle that phages can infect the live Mycobacterium tuberculosis in the specimen under suitable conditions and produce plaques.Other phage-based diagnostic methods,such as a combination of the amplified biologically assay and nucleic acid amplification or lateral flow assays,are also actively explored.This review will help us improve the understanding of mycobacteriophages in TB detection and better promote the development of the rapid diagnosis of M.tuberculosis.

Selection of Phage-resistant Strains from Escherichia coli glyA Genetic Engineering Bacteria

[ Objective] This study aimed to select E. coli strains with phage-resistance. [ Method] Phage-resistant strains of E. coli glyA genetic engineering bacteria were selected by phage induction and UV-coupling phage induction. [ Result] By phage induction, 20 strains with stable resistance were selected from the 24 phage-resistant strains, only one strain showed better growth condition than the original strains, but the enzymatic activities of the 20 strains were all lower than the original strains; 41 phage-resistant strains were selected by UV-coupling phage induction, 39 strains of which had better stability, including 7 strains that showed better growth conditions than the original strains and two strains had higher enzymatic activities than the original strains. [ Conclusion] UV-coupling phage induction is a suitable method to select phage-resistant strains from Ecoli genetic engineering bacteria.

Application of phage display technology in targeted therapy of breast cancer

Phage display is a technology of gene expression and screening, it is widely used in the fields of defining antigen epitopes, signal transduction, genetic treatment, parasites research and tumor targeted therapy. Breast cancer is the most common cancer in women, we can obtain peptides specially associated with breast cancer by using phage display technology, and this method has great potential in early diagnosis of breast cancer and development new targeted drugs.

Therapeutic Potential of Staphylococcal Bacteriophages for Nasal Decolonization of <i>Staphylococcus aureus</i>in Mice

Bacteriophages represent a rich and unique resource of anti-infectives to counter the global problem of antibiotic resis- tance. In this work, we assessed the bactericidal activity of two virulent staphylococcal phages, K and 44AHJD, against S. aureus isolates of clinical significance, and tested their efficacy in vivo. The phage cocktail lysed >85% of the clinical isolates tested. Both the phages were purified by ion-exchange column chromatography following propagation in bioreactors. The purity profiles of the ion-exchange purified phages were compared with those of phages purified using cesium chloride density gradient ultracentrifugation, and infectiousness of the purified phages was confirmed by plaque forming assay. The in vivo efficacy of a phage cocktail was evaluated in an experimental murine nasal colonization model, which showed that the phage cocktail was efficacious. To our knowledge, this is the first report of phage use in an in vivo model of nasal carriage.

Determining the Minimum Inhibitory Concentration of Bacteriophages: Potential Advantages

The minimum inhibitory concentration (MIC) is the concentration at which an antibacterial agent experiences the complete inhibition of organism growth. Bacteriophages represent a rich and unique resource of anti-infectives to counter the growing world-wide problem of antibiotic resistance. In this study, we compared the host range of lytic bacteriophages and temperate phagesbelonging to various genera, namely Staphylococcus, E. coli and Salmonella, with a range of clinical isolates using two methods: the classical agar overlay method and a newly developed MIC method. MIC was only observed with isolates that were susceptible to phage infection, which correlated with the agar overlay assay, whereas no MIC was detected with isolates that were resistant to phage infection. The simple MIC method was useful in determining phage adsorption and host range, and detecting possible prophage contamination in phage preparations. Interestingly, this method was also applicable to strain differentiation through phage susceptibility testing using a 96-well, high throughput format that proved to be easy, cost-effective, fast and reliable.

Application of M13 Phage Coat Proteins

M13 phage＇is a filamentous bacteriophage containing a circular single-stranded DNA molecular, which is surrounded by approximately 2 800 copies of protein PVIII. In addition, there are five copies of each of proteins PVII and PXI in one end, and five copies of each of proteins PVI and PUI on the other. These coat proteins have play an important role in the infection and assembly of M13 phage. With the development of phage display technology, these five coat proteins all can be used in phage display, which plays an increasingly important role in molecular detection and treatment.

The Structural Proteins of Bdellovibrio bacteriovorus Bacteriophage MAC-1

In the present investigation the structural proteins associated with MAC-1 bacteriophage have been characterized using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE);tandem mass spectrometry of protein bands from SDS-PAGE gel;from the open reading frames (ORFs) deduced from MAC-1 genome sequence and amino acid sequence homology searches from the Uniprot database (up000002418). Results have led to the identification of at least three structural proteins associated with MAC-1 phage genome. They are: capsid protein (~55,000-daltons);spike protein (~22,000-daltons) and a low molecular weight DNA binding protein (~4000-dal- tons). In addition, two other minor proteins were tentatively identified as replicative and scaffold proteins based on two to three unique peptides from mass spectrometry data. However, other proteins coded (ORFs) by phage genome remain to be identified.