From the hospital wastewater, a novel bacteriophage was isolated and characterized. According to characterization properties, this bacteriophage belongs to the Siphoviridae family, the maximum bacteriophage titer was recorded at 37°C and a pH of 7.2, had a 44,789 bp linear double-strand DNA genome, and within the genome sequence, there are 61 genes, all of which are encoded into proteins. Although this bacteriophage does not have any virulence factors or antimicrobial resistance genes and had specific lytic activity against some antimicrobial resistance S. aureus clinical isolates.

Presence of lipopolysaccharides (LPSs) in the outer layer of outer membranes (OMs) is an almost universal molecular signature of Gram-negative bacteria. The O-antigen or O-polysaccharide (OPS) chains attach to millions of LPS molecule to form a continuous layer on the surface of most of Escherichia coli strains. OPS structure is one of the most variable features of bacteria, with about 200 E. coli O-serotypes currently described. In this review a analyze accumulating evidence suggesting that a vast majority of these OPS types provide robust shields that restrict the access of large molecules to the OM surface. Sophisticated mechanisms employed by bacteriophages to penetrate the OPS barrier are also considered. These are initiated with specific recognition of OPS molecules by phage receptor-binding proteins (RBP), or of other cell-surface molecules that are exposed above the OPS layer. Only after can virions gain access to secondary receptors found closer to the OM surface. The mechanisms of breaking through OPS in most if not all cases appear to rely on mechanical force generated by molecular motors of processive depolymerization or deacetylation of cell surface polysaccharides by enzymatically active RBPs, or by internal rearrangement of the virion.

Healthcare faces a major problem with the increased emergence of antimicrobial resistance due to the over-prescription of antibiotics. This causes dysbiosis and major disruption of the gut microbiome, leading to the development of intestinal diseases, abnormalities in the regulation of immune responses, malfunctioning of entero-endocrine signaling, and an imbalance in communication with the central nervous system (CNS). Bacteriophages may provide a solution to the treatment of bacterial infections given their specificity. This approach increased rapidly over the last ten years, because of the rapid rise of multi-drug-resistant bacteria worldwide coupled with a decline in the development and production of novel antibacterial agents. Eradication of multidrug-resistant bacteria is often only possible with bacteriophage treatment. Phage proteins are used to stimulate immune responses against specific pathogens, improve antibiotic susceptibility, prevent biofilm formation, and characterize bacterial pathogens. This review discusses the therapeutic potential of bacteriophage-derived proteins.

Escherichia coli phage Eco_BIFF was isolated from several laboratory stocks of E. coli K-12 MG1655 derivatives. The source of the contamination is unknown. Eco_BIFF is a lytic phage that shows effective growth inhibition of E. coli K-12. Here, we announce the complete genome sequence of Eco_BIFF, and major findings from its genome annotation.

Many dairy industries use their own starter cultures rather than Direct vat set culture because of their novelty and specific sensory characteristic it provides to their products. Starter culture rotation is not always possible, if the process involves the use of novel strains. The presence of bacteriophages in the environment leads to the quality instability of the product leads to the unexpected fermentation failure. In this context, a study of the prevalence of bacteriophages in the different sectors of dairy environment is carried out. The Screening of the phages has been undertaken with cheese and yoghurt cultures in the production and processing area. Three tests have been carried out to isolate the phages. Viz., turbidity test, double layer plaque assay, Spot test. Two natural temperate phages have been isolated from the cheese and yoghurt culture. Whereas the samples from the dairy processing environment is negative for phages. The temperate phages belong to the Siphoviridae family. Certain processing area where there is no involvement of starter culture e.g., paneer whey also showed the presence of phages in the whey, which indicates the air borne transmission of phages. Thus, the goal of this article is to make the quality assurance program associated with the production process of the fermented dairy products for the presence of phages in the dairy environment, with special emphasis on the preventive aspects related to this problem in the dairy fermentative industry.

Salmonella enterica serovar Newport bacteriophage 7-11 shares 41 homologous ORFs with Escherichia coli phage phiEco32 and both phages encode a protein similar to bacterial RNA polymerase promoter specificity  subunit. Here, we investigated the temporal pattern of 7-11 gene expression during the infection and compared it to the previously determined transcription strategy of phiEco32. Using primer extension and in vitro transcription assays we identified eight promoters recognized by host RNA polymerase holoenzyme containing 7-11  subunit SaPh711_gp47. These promoters are characterized by a bipartite consensus GTAAtg-(16)-aCTA and are located upstream of late phage genes. While dissimilar from single-element middle and late promoters of phiEco32 recognized by holoenzyme formed by the phi32_gp36  factor, the 7-11 late promoters are located at genome positions similar to those of phiEco32 middle and late promoters. Two early 7-11 promoters are recognized by RNA polymerase holoenzyme containing host primary σ70 factor. Unlike the case of phiEco32, no shut off of σ70-dependent transcription is observed during 7-11 infection and there are no middle promoters. These differences can be explained by the fact that phage 7-11 does not encode a homologue of phi32_gp79, an inhibitor of host and early phage transcription and an activator of transcription by the phi32_gp36-holoenzyme.

The objective of this study was to evaluate the effects of dietary supplementation with bacteriophage and β-mannanase on health and growth performance in calves. Thirty-six pre-weaning male Holstein calves were randomly allocated to one of four dietary treatments: no supplementation, 0.1% β-mannanase, 0.1% bacteriophage, and both 0.1% bacteriophage and β-mannanase supplementation in a starter. The experiment lasted from 2 weeks before weaning to 8 weeks after weaning. Twenty-two calves survived to the end of the experiment. No interaction was observed between the two methods of supplementation. A 1-kg increase in initial BW resulted in a 1.41-fold increase in the odds ratio of survival (p < 0.01). The bacteriophage supplementation tended to increase the odds ratio of survival (p = 0.09). The number of Escherichia coli in feces significantly decreased one week after weaning. β-mannanase supplementation increased the concentrates intake (p < 0.01) and tended to increase the final BW (p = 0.08). Analysis of repeated measures indicated β-mannanase supplementation increased weekly body weight gain (p = 0.018). We conclude that bacteriophage supplementation may have a positive effect on calf survival rate, while β-mannanase supplementation may increase the growth rate and intake of a starter in calves.

The main function of dUTPases is to regulate the cellular levels of dUTP and dTTP, thereby playing a crucial role in the DNA repair mechanisms. Despite the fact that mutant organisms with the obliterated dUTPase enzymatic activity remain viable, it is not possible to knockout the dut gene completely due to the lethal consequences of such mutation for the organism. As a result, it is considered that this class of enzymes perform an additional function that is essential for the organism's survival. In this study, we provide the evidence that the dUTPase of bacteriophage T5 possesses supplemental function in addition to its canonical role. We determined the crystal structure of bacteriophage T5 dUTPase with a resolution of 2.0 Å, and discovered a distinct short loop, consisting of 6 amino acid residues which represents unique structural feature specific to the T5-like phages dUTPases. The removal of this element did not affect the overall structure of the homotrimer, but had significant effects on the development of the phage. Furthermore, it has been shown that the enzymatic function and the novel function of bacteriophage T5 dUTPase are unrelated and independent from each other.

The emergence of multidrug-resistant bacterial strains, especially in the clinical setting, has renewed interest in alternative treatment methods. The utilization of prokaryotic viruses in phage therapy has demonstrated potential as a novel treatment method against multidrug-resistant bacterial infections. As the post-antibiotic era quickly approaches, the development and standardization of phage therapy is critically relevant to public health. This review serves to highlight the development of phage therapy against methicillin-resistant Staphylococcus aureus (MRSA), an antibiotic-resistant bacterial strain responsible for severe clinical infections.

The prevalence of multidrug resistant bacterial diseases is a major global health risk. Multidrug resistant bacterial diseases are prevalent, and the need for novel methods of treatment is essential to the preservation of public health. Annually foodborne pathogens cause 1.35 million infections and 26,500 hospitalizations in the United States alone. Foodborne pathogens such as Salmonella spp. are a major threat to public health. Bacteriophages offer a unique method for the treatment of these multidrug resistant bacteria. We studied the infection dynamics of a potential mono-phage therapy of Salmonella typhimurium under various pathophysiological conditions. Furthermore, we determined the resistance dynamics of Salmonella typhimurium against P22 phage treatment. We also determined synergy with antibiotics such as ampicillin and kanamycin. This research helps to further define and show the versatility of bacteriophages as potential novel treatment methods.

Recently the polyvalent bacteriophage FP01, isolated from wastewater in Valparaiso, Chile, was described to have lytic activity across species against Escherichia coli and Salmonella enterica serovars. Due to it polyvalent nature the bacteriophage FP01 could have potential application in food and agri-industry. Also, fundamental aspects of polyvalent bacteriophage biology are not well known. In this study we sequenced and describe the complete genome of the polyvalent phage FP01 (MH745368) using the nanopore technology. The bacteriophage FP01 genome has a 44,900 bp, double-stranded DNA with an average G+C content of 49.41% and 90 coding sequences (CDSs). We found that the phage FP01 critically depends on host factors for replication and transcription. Also, it has a critical lysogenic repressor pseudogene. Phylogenetic analyses indicated that the phage FP01 is closely related to phages lambda and P22. These results suggest that the phage FP01 could be a lytic variant of a lysogenic phage or acquired genes from lysogenic phages during host infection.

The human virome is an area of increasing interest with relation to human health and disease. It has been demonstrated to alter in concert with the bacterial microbiome in early life and was also found to be different in patients with certain diseases such as inflammatory bowel disease. However, all virome analyses are hampered by a lack of annotated representative database sequences, often referred to as the ‘viral dark matter’. Here we provide the first description of the gut DNA virome in elderly individuals (>65 years old) as well as the description of novel bacteriophages not present in current reference databases. Diversity analysis comparing elderly persons from different residence locations (community living vs long term care facilities) did not reveal any difference in their virome diversity profiles despite the reported differences at the bacteriome level. An abundance of Microviridae of the subfamily Gokushovirinae were present in the faeces of elderly individuals. Several novel members of the order Caudovirales were also characterized and annotated. Assignment of host bacteria to detected viral genomes was attempted using a combination of CRISPR spacers, tRNA genes and a probabilistic approach. Further characterization of the viral dark matter is necessary for developing tools and expanding databases to study the human virome. This study focused on the virome of an aging human cohort with the goal of illuminating part of the viral dark matter.

Urinary tract infections (UTIs) caused by Klebsiella pneumoniae can lead to severe clinical complications and even death. An alternative treatment option for infected patients is using bacteriophages (phages). In the present study, we isolated phage KP-1 from sewage water using K. pneumoniae as a host. Whole genome analysis indicated that the genome was a double-stranded linear 176,096-bp long DNA molecule with 41.8% GC content and did not contain virulence or antibiotic resistance genes. The inactivation potential of phage KP-1 was assessed in broth at an MOI of 1 and 10, and a maximum inactivation of 4.9 and 5.4 log CFU/mL was observed after 9 h, respectively. The MOI of 10 efficacy was also assessed in urine to evaluate the phage’s performance in an acidic environment. A maximum inactivation of 3.8 log CFU/mL was observed after 9 h. The results indicate that phage KP-1 could be used to control UTIs caused by K. pneumoniae; however, further studies using phage cocktails to broader the phage’s spectrum of activity and phages in micro- or nanocarriers to avoid the negative effect of the low pH of the urine on phage viability, are necessary.

Bioinformatics analysis of the sequences of orthologous zinc-containing peptidases of the M15_C subfamily revealed the presence of a conserved tryptophan residue near the active site, which is not involved in the formation of the protein core. Site-directed mutagenesis of this Trp114/109 residue using two representatives of the family, L-alanoyl-D-glutamate peptidases of bacteriophages T5 (Calcium-activated EndoT5) and RB49 (EndoRB49, without ion regulation) as an example, and further analysis of the 1H NMR spectra of the mutants showed that a decrease in the volume of the W → F → A residue leads to changes in the hydrophobic core and active center of the protein, and also decreased affinity for regulatory Ca2+ in the EndoT5 mutants. The inactive T5W114A mutant lacks the ability to bind the substrate. In general, the conserved Trp114/109 residue, due to the spatial restrictions of its side chain, significantly affects the formation of the catalytically active form of the enzyme and is critical for catalysis.

Cholera is an acute enteric infectious disease caused by the Gram-negative bacterium Vibrio Cholerae. Despite a huge body of research, the precise nature of its transmission dynamics has yet to be fully elucidated. Mathematical models can be useful to better understand how an infectious agent can spread and be properly controlled. We develop a compartmental model describing a Human population, a bacterial population as well as a phage population. We show that there might be eight equilibrium points; one of which is a disease free equilibrium point. We carry out numerical simulations and sensitivity analyses and we show that the presence of phage can reduce the number of infectious individuals. Moreover, we discuss the main implications in terms of public health management and control strategies.

Probiotics are increasingly used by consumers and practitioners to reduce gastrointestinal (GI) distress and improve gut function. Here, we sought to determine whether addition of supplemental bacteriophages (PreforPro) could enhance the effects of a common probiotic, Bifidobacterium animalis subsp. lactis (B. lactis) on GI health. We conducted a 4-week, randomized, parallel-arm, double-blind, placebo-controlled trial where primary outcomes included self-assessments of GI health, a daily stool log, and 16s rRNA analysis of gut microbial populations. We observed within group improvements in GI inflammation (p=0.01) and a trending improvement in colon pain (p=0.08) in individuals consuming B. lactis with PreforPro, but not in the group consuming only the probiotic. There was also a larger increase in Lactobacillus and short chain fatty acid-producing microbial taxa detected in stool of participants taking PreforPro with B. lactis compared to the probiotic alone. Overall, these results suggest the addition of PreforPro as a combination therapy may alter gut ecology to extend the GI benefits of consuming B. lactis or other probiotics.

Enterococcus faecalis is a growing cause of nosocomial and antibiotic-resistant infections. Treating drug-resistant E. faecalis requires novel approaches. The use of bacteriophages (phages) against multidrug-resistant (MDR) bacteria has recently garnered global attention. Biofilms play a vital role in E. faecalis pathogenesis as they enhance antibiotic resistance. Phages eliminate biofilms by producing lytic enzymes, including depolymerases. In this study, Enterococcus phage vB_Efs8_KEN04 (ФKEN04), isolated from a sewage treatment plant in Nairobi, Kenya, was tested against clinical strains of MDR Enterococcus faecalis. This phage had a broad host range against 100% (26/26) of MDR E. faecalis clinical isolates and cross-species activity against Enterococcus faecium. It was able to withstand acidic and alkaline conditions, from pH 3 to 11, as well as temperatures between -80ᵒC and 37ᵒC. It could inhibit and disrupt the biofilms of MDR E. faecalis. Its linear double-stranded DNA genome of 142,402 bp contains 238 coding sequences with a G+C content and coding gene density of 36.01% and 91.46%, respectively. Genomic analyses showed that ФKEN04 belongs to the genus Kochikohdavirus in the family Herelleviridae. It lacked antimicrobial resistance, virulence, and lysogeny genes, and its stability, broad host range, and cross-species lysis indicate strong potential for the treatment of Enterococcus infections.

Bacteriophages (phages) are potential alternatives to chemical antimicrobials against pathogens of public health significance. Understanding the diversity and host specificity of phages is important for developing effective phage biocontrol approaches. Here, we assessed the host range, morphology, and genetic diversity of eight Salmonella enterica phages isolated from a wastewater treatment plant. The host range analysis revealed that six out of eight phages lysed more than 81% of the 43 Salmonella enterica isolates tested. The genomic sequences of all phages were determined. Whole genome sequencing data (WGS) data revealed that phage genome sizes ranged from 41 to 114 kb with GC contents be-tween 39.9 and 50.0 %. Two of the phages SB13 and SB28 represent new species Epsep-timavirus SB13 and genera Macdonaldcampvirus, respectively as designated by the In-ternational Committee for the Taxonomy of Viruses (ICTV) as per genome based taxonomic classification. One phage (SB18) belonged to the Myoviridae morphotype while the re-maining phages belonged to the Siphoviridae morphotype. The gene content analyses showed that none of the phages possessed virulence, toxin, antibiotic resistance, type I-VI toxin-antitoxin modules or lysogeny genes. Three (SB3, SB15 and SB18) out of the eight phages possessed tailspike proteins. Whole genome-based phylogeny of the eight phages with their 113 homologs revealed three clusters A, B, C and seven subclusters (A1, A2, A3, B1, B2, C1 and C2). While cluster C1 phages were predominantly isolated from animal sources, cluster B contained phages from both wastewater and animal sources. The broad host range of these phages highlights their potential use to control the presence of S. enterica in foods.

The molecular mechanism how the infecting DNA of bacteriophage T4 is passing from the capsid through the bacterial cell wall and entering the cytoplasm is essentially unknown. After adsorption, the short tail fibers of the infecting phage extend from the baseplate and trigger the contraction of the tail sheath, leading to a puncturing of the outer membrane by the tail tip needle composed of the proteins gp5.4, gp5 and gp27. To explore the events that occur in the periplasm and at the inner membrane, we have constructed T4 phage that have a modified gp27 in their tail tip with a His-tag. Shortly after infection with these phages, the cells were chemically cross-linked, solubilised, and the cross-linked products were affinity purified on a nickel column. The co-purified proteins were identified by mass spectrometry, and we found that predominantly the inner membrane proteins DamX, SdhA and PpiD were cross-linked. The same partner proteins were identified when purified gp27 was added to Escherichia coli spheroplasts suggesting a direct protein-protein interaction.

The Burkholderia cepacia complex (Bcc) are a group of increasingly multi-drug resistant opportunistic bacteria that can cause severe pulmonary infections. This resistance is driven through a combination of intrinsic factors and the carriage of a broad range of conjugative plasmids harbouring virulence determinants. Therefore, novel treatments are required to not only treat Bcc infection but also to prevent further spread of these virulence determinants. In the search for phages infective for two clinical Bcc isolates, CSP1 phage, a PRD1-like phage was isolated. CSP1 phage was found to require pilus machinery commonly encoded on conjugative plasmids to facilitate infection of multiple Gram-negative bacteria genera including Escherichia and Pseudomonas. Whole genome sequencing and characterisation of one of the clinical Burkholderia isolates revealed it to be Burkholderia contaminans. B. contaminans 5080 was found to contain a genome of over 8 Mbp encoding multiple intrinsic resistance factors, such as efflux pump systems, but more interestingly, carried three novel plasmids encoding multiple putative virulence factors for increased host fitness, including antimicrobial resistance. Even though PRD1-like phages are broad host range, their use in novel antimicrobial treatments shouldn’t be dismissed, as the dissemination potential of conjugative plasmids is extensive. Continued survey of clinical bacterial strains is

Staphylococcal bacteriophages of Kayvirus genus are candidates for therapeutic applications. One of their proteins, Tgl, is slightly similar to staphylococcal virulence factors, secreted autolysins of lytic transglycosylase motifs, IsaA and SceD. We show that Tgl is also a lytic enzyme secreted by bacterial transport system and localizes to cell peripheries, like IsaA and SceD. It caused lysis of E. coli cells expressing the cloned tgl gene, but could be overproduced when depleted of signal peptide. S. aureus cells producing Tgl lysed in the presence of nisin, which mimics the action of phage holin. In vitro, Tgl protein was able to destruct S. aureus cell walls. The production of Tgl decreased S. aureus tolerance to vancomycin, unlike the production of SceD, which is associated with the decreased sensitivity to vancomycin. In the genomes of kayviruses, the tgl gene is located a few genes away from gene lysK, encoding the major endolysin. While lysK is a late phage gene, tgl can be transcribed by a host RNA polymerase, as are phage early genes. Taken together our data indicate that tgl is a part of kayviruses lytic module and encodes an additional endolysin which can act in concert with LysK in cell lysis.

Background: Dual function tail tubular proteins (TTP) belonging to the lytic bacteriophages are the interesting group of biologically active enzymes. Surprisingly, apart from their structural function, they are also polysaccharide hydrolyzes destroying bacterial extracellular components. One of the representatives of this group is TTPB from Klebsiella pneumoniae phage – KP32. TTPB hydrolyzes exopolysaccharide (EPS) of Klebsiella pneumoniae and Enterococcus faecalis strain. This depolymerizing feature was associated with the activity to prevent bacterial biofilm formation. TTPB can inhibit biofilm formation by K. pneumoniae, Enterobacter cloacae, Staphylococcus aureus, Enterococcus faecalis and Pseudomonas aeruginosa strains. Moreover, synergistic activity with antibiotic action has been observed, most likely due to depolymerases’ facilitation of contact of antibiotic with bacterial cells. Methods: TTPB was overexpressed in E coli system, purified and tested towards the bacterial strains using agar overlay method. The hydrolytic activity of TTPB was performed using EPSs of K. pneumoniae PCM2713 and E. cloacae ATCC 13047 as the substrates. Next, we determined the reducing sugar (RS) levels in the TTPB/EPS mixtures, regarding the RS amount obtained after acidic hydrolysis. The antibiofilm activity of TTPB has been set down on bacterial biofilm using a biochemical method. Finally, we have demonstrated the synergistic activity of TTPB with kanamycin. Results: For the first time, the hydrolytic activity of TTPB towards bacterial EPSs has been shown. TTPB releases about a half of the whole RS amount of EPSs belonging to K. pneumoniae PCM 2713 and E. cloacae ATCC 13047 strains. 1.12 µM of the phage protein reduces biofilm of both strains by over 60%. Destroying the bacterial biofilm the phage protein improves the antibiotic action increasing kanamycin effectiveness up to four times.

Scaffolds used for tissue/ bone defect repair must possess versatile properties suitable for each specific application. The issue of antibiotic resistance poses a significant challenge in bone tissue engineering especially when dealing with microbial infections. The most effective approach to address this challenge is to promote the integration of tissue before bacteria can adhere to it, hence preventing the proliferation of certain bacterial strains on the implant. The utilization of 3D printing and or the use of various composite polymers in scaffolds to create antibacterial scaffolds that possess both adequate mechanical strength and exceptional biocompatibility is an attractive approach for addressing the challenges associated with microbial infections in tissue. Herein, a new phage functionalized scaffold was created through surface charge modification of the composite scaffold with polyethyleimine (PEI). Afterwards, the PEI polymerized Scaffolds were incubated with phage lysate for approximately 2h prior to rinsing with ethanol. The morphological and physiochemical properties of formed scaffold were assessed through Raman spectrophotometry while the antibacterial assays were done through growth inhibition zones/ cell viability assays. The polymerized phage composite SF20_PEI.AR9 possessed the highest antimicrobial effect with clear inhibition zones of about 78.30 mm. This could be attributed to the lytic effect of phages on the bacterial cells. Moreover, the enhanced phage effect on the scaffolds was also associated to the improved surface charge on the scaffold, 78,3±7,6 mm which ultimately promoted phage scaffold interface integration hence the high antibacterial activity. The PEI polymerization approach could serve as a model for future development of phage scaffolds.

Bacteria are engaged in a constant battle against preying viruses, called bacteriophages (or phag-es). These remarkable nano-machines pack and store their genomes in a capsid and inject it into the cytoplasm of their bacterial prey following specific adhesion to the host cell surface. Tailed phages possessing dsDNA genomes are the most abundant phages in the bacterial virosphere, particularly those with long, non-contractile tails. All tailed phages possess a nano-device at their tail tip that specifically recognizes and adheres to a suitable host cell surface receptor, being pro-teinaceous and/or saccharidic. Adhesion devices of tailed phages infecting Gram-positive bacte-ria are highly diverse and, for the majority, remain poorly understood. Their long, flexible and multi-domain encompassing tail limits experimental approaches to determine their complete structure. We have previously shown that the recently developed protein structure prediction program AlphaFold2 can overcome this limitation by predicting the structures of phage adhesion devices with confidence. Here, we extend this approach and employ AlphaFold2 to determine the structure of a complete phage, the lactococcal P335 phage TP901-1. Herein we report the structures of its capsid and neck, its extended tail, and the complete adhesion device, the baseplate, which was previously partially determined by X-ray crystallography.

The dynamic and surface manipulation of the M13 bacteriophage meeting application demands enable a pathway to design efficient applications with high selectivity and responsivity rate. Herein, we report the role of the M13 bacteriophage thin film layer deposited on an optical nanostructure involving gold nanoparticles/SiO2/Si and its influence on optical and geometrical properties. The thickness of the M13 phage layer was either controlled by varying the concentration or humidity exposure levels, and optical studies were conducted. We designed a standard and dynamic model based upon three-dimensional finite-difference time-domain (3D FDTD) simulations distinguishing the necessity of each model under variable conditions. As seen from the experiments, the origin of respective peak wavelength positions is addressed in detail with the help of simulations. The importance of the dynamic model was noted when humidity-based experiments were conducted. Inexpensive, multi-wavelength optical characteristics from a single structure, reproducibility, and reversible properties are significant advantages of involving M13 bacteriophage. We believe this work will provide fundamental insight into understanding and interpreting the geometrical and optical properties of the nanostructures involving M13 bacteriophage.

Bacteriophages, viruses that are widespread throughout the world, are highly specific for bacteria, usually of a single species and often of a particular strain. After being discovered and isolated 100 years ago, their use, called phage therapy, was instituted in medicine two years later and quickly used around the world to treat various bacterial infections. In the West, phage therapy was overshadowed in the second half of the 20th century by antibiotic therapy, which was then thought to be the definitive solution. But because of the increase in bacterial resistance to antibiotics, the idea of using bacteriophages in medicine has been reawakened. The innumerable observations reported over the years in the literature constitute an invaluable experience. We and some of our colleagues have, in the last decade treated some patients compassionately. With the available documentation and our own experience we discuss the potential indications and limitations of phage therapy. The observation of the increasing number of therapeutic failures in the announced perspective of a post-antibiotic era, we believe, that the introduction of bacteriophages into the therapeutic arsenal seems conceivable today to two preconditions: that their production as biologic drug meets current regulatory standards and that the benefit-risk assessment was conducted in a modern setting. Phage therapy could be applied as a substitution or supplement to antibiotic therapy under multiple circumstances in different modes, precise indications and limits.

Bacteria of the genus Staphylococcus are a significant a challenge for medicine, as many species are resistant to multiple antibiotics and even to all of the antibiotics used. One of the approaches to develop new therapeutics to treat staphylococcal infections is the use of bacteriophages specif-ic to these bacteria or lysins of such bacteriophages capable to hydrolyze the cell walls of these bacteria. In this study, a new bacteriophage St_134 specific to Staphylococcus epedermidis was de-scribed. This small podophage belonging to the Andhravirus genus showed relatively wide host range and was able to infect more than 60 strain of Staphylococcus spp., including a clinical strain from the Staphylococcus aureus complex. Two genes encoding different phage lysins were identi-fied in the Ste134 genome. Both lysins LysSte134_1 and LysSte134_2 were produced in Escherichia coli cells. Endolysin LysSte134_1 was demonstrated catalytic activity against a wide panel of staphylococcal peptidoglycans (4 species, 6 strains), was active against S. aureus and S. epidermidis planktonic cultures and destroyed biofilms formed by clinical strains of S. aureus and S. epider-midis.

The current pandemic is urgently demanding to discover alternative materials capable of inactivate the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes the coronavirus 2019 (COVID-19) disease. Calcium alginate is a crosslinked hydrophilic biopolymer with an immense range of biomedical applications due to its excellent chemical, physical and biological properties. In this study, the cytotoxicity and antiviral activity of calcium alginate in the form of films were studied. The results showed that these films are biocompatible in human keratinocytes and are capable of inactivating enveloped viruses such as bacteriophage phi 6 with a 1.43-log reduction (94.92% viral inactivation) and SARS-CoV-2 Delta variant with a 1.64-log reduction (96.94% viral inactivation) in virus titers. The antiviral activity of these calcium alginate films can be attributed to its negative charge density that may bind to viral envelopes inactivating membrane receptors.

Streptococcus mutans is a key bacterium in dental caries- one of the most prevalent chronic infectious diseases. Conventional treatment both fails to specifically target the pathogenic bacteria and at-tempts to eradicate commensal bacteria as well. Thus, caries remains one of most common and challenging diseases. The use of bacterial viruses as anti-bacterial agents, is gaining interest worldwide. Hardly any phages were described against S. mutans. The objective of this study was to isolate anti-S. mutans phages and to characterize their antimi-crobial properties. Human saliva samples were filtered and screened for potential phages. Standard double-layered agar method was used for isolation. Whole genome sequence analysis and morphology visualization by TEM, were used for anti-S. mutans phage identification. Antibacterial properties were evaluated using clinical strains and ATCC strains of S. mutans in various states. Antibacterial effect was also tested on human cariogenic dentin. One phage against S. mutans was isolated and termed SMHBZ8. This phage showed effective lytic activity in vitro against both planktonic and biofilm S. mutans cultures. Moreover, the phage showed antibacterial effect when used on cariogenic dentin. The isolation and characterization of SMHBZ8 may be the first step in developing a potential phage therapy for dental caries.

Factors affecting the host-virus interaction must be understood for the effective application of bacteriophages to combat bacterial pathogens. Two novel E. coli phages, the T1-like siphophage LL5 and the rV5-like myophage LL12, were subjected to forward genetic screens against the Keio collection, a library of single non-essential gene deletions in E.coli str. BW25113. These genome-wide screens and subsequent experiments identified eight genes required for efficient propagation of phage LL5 and six genes required for propagation of LL12. The majority of the genes identified were involved in production of the phage receptors. E. coli mutants deficient in heptose II and the phosphoryl substituent of heptose I of the inner core lipopolysaccharide (LPS) were unable to propagate phage LL5, as were mutants deficient in the outer membrane protein TolC. Mutants lacking glucose I of the LPS outer core failed to propagate LL12. Two cytoplasmic chaperones, PpiB and SecB, were found to be required for efficient propagation of phage LL5 but not LL12. This approach may be useful for identifying phage receptors and required host factors in other phages, which would provide valuable information for their potential use as therapeutics and for phage engineering.

The objective of the present study is to isolate phages targeting multidrug resistant (MDR), extended spectrum beta lactamase (ESBL) positive clinical isolate of E. coli ( U1007), sequence and analyze the phage genome and use machine learning tools to predict host cell surface receptor and finally evaluate the efficiency of monophage and phage cocktail in vitro and in vivo in a zebrafish model. Phage specific for E. coli U1007 was isolated from Ganges River (designated as U1G), Cuoom River (designated as CR) and Hospital waste water (designated as M phage). The obtained phages were triple purified and enriched. U1G phages had a greater burst size of 124 PFU/cell and a latent time of 25 min.M phage had a burst size of 150 PFU/cell with a shortlatent time of 20min. Similarly CR phage has a short latent 20 min and a burst size of 115 PFU/cell. Based on capsid architecture, U1G phage resembles Podoviridae, CR phage is structurally similar to Myoviridae and M phage has morphology that resembles Siphoviridae. Genome sequencing and analysis revealed that the size of the U1G phage genome is 73275 bp Whereas that of CR phage and M phage are 45236 bp and 45294 bp, respectively. All three genomes were marked by the absence of genes encoding tRNA sequence, antibiotic resistant or virulent genes. A machine learning (ML) based multi-class classification model using algorithms such as Random Forest, Logistic Regression, and Decision Tree were employed to predict the host receptor targeted by all 3 phages and the best performing algorithm Random Forest predicted LPS O antigen , LamB or OmpC for U1G FhuA, OmpC for CR phage and FhuA, LamB, TonB or OmpF for the M phage as the host receptor targeted by the receptor binding protein (RBP) of the phages. In vitro time kill assay showed that treatment with monophages alone and along with colistin resulted in regrowth whereas phage combinations significantly reduced the regrowth and by 24h the phage cocktail along with colistin produced a significant 3 log declinein cell counts relative to the untreated control. In vivo intramuscular infection study in zebrafish showed that phages were non toxic and a cocktail of dual (U1G +M) phage along with colsitin resulted in a significant 3.5 log decline in cell counts whereas triple phage combination along with colistin resulted in 3 log decline in cell counts probably due to host receptor competition. Our study highlights the potential of phage cocktail therapy in mitigating MDR clinical isolate of E. coli in vitro and in vivo.

Vehicle HVAC systems can accumulate and recirculate highly infectious respiratory diseases via aerosols. Integrating UVC to complement automobile HVAC systems can protect occupants from developing allergies, experiencing inflammatory problems, or acquiring respiratory infectious diseases by inactivating pathogenic organisms. UVC can add little to no static pressure with minimal space, unlike mercury lamps which are larger and heavier. Additionally, UVC LEDs are effective at low voltage and have no mercury or glass. While previous experiments have shown UVC LED technology can reduce bacteriophage Phi6 concentrations by 1 log in 5 minutes (selected as the average time to clean the cabin air), those studies had not positioned LED within the HVAC itself or studied the susceptibility of the surrogate at the specific wavelength. This study aimed to assess the disinfection performance of UVC LEDs in automotive HVAC systems and determine the dose-response curve for bacteriophage Phi6, a SARS-CoV-2 surrogate. To achieve this, UVC LEDs were installed in a car HVAC system. To determine inactivation efficacy, a model chamber of 3.5 m3, replicating the typical volume of a car, containing the modified automobile HVAC system was filled with bacteriophage Phi6, and the HVAC was turned on with and without the UVC LEDs being turned on. The results revealed that HVAC complemented with UVC reduced bacteriophage Phi6 levels significantly more than the HVAC alone and reduced the viral concentration in the cabin by more than 1 LRV (90% viral reduction) in less than 5 minutes. The performance after 5 minutes is expected to be significantly better against SARS-CoV-2 because of its higher sensitivity to UVC, especially at lower wavelengths (below 270 nm). HVAC alone could not achieve a 90% viral reduction of bacteriophage Phi6 in 15 minutes. Applying UVC LEDs inside an HVAC system is an effective means of quickly reducing the number of aerosolized viral particles in the chamber, by inactivating microorganisms leading to improved cabin air quality.

Abstract: With the availability of an increasing number of 3D structures of bacteriophage components, combined with powerful in silico predictive tools, it has become possible to decipher the structural assembly and functionality of phage adhesion devices. In the current study, we examined 113 members of the 936 group of lactococcal siphophages, and identified a number of Carbohydrate Binding Modules (CBMs) in the neck passage structure and major tail protein, on top of evolved Dit proteins as recently reported by us. The binding ability of such CBM-containing proteins was assessed through the construction of green fluorescent protein fusion proteins and subsequent binding assays. Two CBMs, one from the phage tail and another from the neck, demonstrated definite binding to their phage-specific host. Bioinformatic analysis of the structural proteins of 936 phages reveals that they incorporate binding modules which exhibit structural homology to those found in other lactococcal phage groups and beyond, indicating that phages utilize common structural “bricks” to enhance host binding capabilities. The omnipresence of CBMs in Siphophages supports their beneficial role in the infection process, as they can be combined in various ways to form appendages with different shapes and functionalities, ensuring their success in host detection in their respective ecological niches.

The mechanisms by which bacteriophage T4 converts the metabolism of its E. coli host to one dedicated to progeny phage production was the subject of decades of intense research in many labs from the 1950’s through the 1980’s. At this point, a wide range of phages are starting to be used therapeutically and in many other applications and also the range of available phage sequence data is skyrocketing. It is thus important to re-explore the extensive available data about the intricacies of the T4 infection process as summarized here, expand it to looking much more broadly at other genera of phages, and explore phage infections using newly-available modern techniques and a range of appropriate environmental conditions.

Concatemeric viral DNA is packaged into Bacteriophage P22 procapsids via a headful packaging mechanism mediated by a molecular machine consisting of small (gp3) and large (gp2) terminase subunits. Although a negative stain reconstruction exists for the terminase holoenzyme, it is not clear how this complex binds dodecameric portal protein located at a 5-fold mismatch vertex. Herein, we describe new assemblies for the holoenzyme. Both native mass spectrometry and transmission electron microscopy reveal that the P22 terminase complex adopts three main assemblies, which include a nonameric S-terminase bound to two L-terminase 1(gp3)9:2(gp2), two nonameric S-terminase bound to five L-terminase 2(gp3)9:5(gp2), and three nonameric S-terminase bound to seven L-terminase 3(gp3)9:7(gp2). Native agarose gel electrophoresis shows that the terminase complex interacts with procapsid with mild crosslinking. These results herein illustrate the P22 terminase complex can adopt a variety of confirmations and assembly states.

Tailed phages are the most abundant and diverse group of viruses on the planet. Yet, the smallest tailed phages display relatively complex capsids and large genomes compared to other viruses. The lack of tailed phages forming the common icosahedral capsid architectures T = 1 and T = 3 is puzzling. Here, we extracted geometrical features from high-resolution tailed phage capsid reconstructions and built a statistical model based on physical principles to predict the capsid diameter and genome length of the missing small tailed phage capsids. We applied the model to 3,348 isolated tailed phage genomes and 1,496 gut metagenome-assembled tailed phage genomes. Four isolated tailed phages were predicted to form T = 3 icosahedral capsids, and twenty-one metagenome-assembled tailed phages were predicted to form T < 3 capsids. The smallest capsid predicted was a T = 4/3 ≈ 1.33 architecture. No tailed phages were predicted to form the smallest icosahedral architecture, T = 1. We discuss the feasibility of the missing T = 1 tailed phage capsids and the implications of isolating and characterizing small tailed phages for viral evolution and phage therapy.

Many microbes live in habitats below their optimum temperature. Retention of metabolic heat by aggregation or insulation would boost growth. Generation of excess metabolic heat may also provide benefit. A cell that makes excess metabolic heat pays the cost of production, whereas the benefit may be shared by neighbors within a zone of local heat capture. Metabolic heat as a shareable public good raises interesting questions about conflict and cooperation of heat production and capture. Metabolic heat may also be deployed as a weapon. Species with greater thermotolerance gain by raising local temperature to outcompete less thermotolerant taxa. Metabolic heat may provide defense against bacteriophage attack, by analogy with fever in vertebrates. This article outlines the theory of metabolic heat in microbial conflict and cooperation, presenting several predictions for future study.

Diversity-generating retroelements (DGRs) are prokaryotic systems providing rapid modification and adaptation of target proteins. In phages, the main targets of DGRs are receptor-binding proteins that are usually parts of tail structures and the variability of such host-recognizing structures enables phage adaptation to changes on the bacterial host surface. Sometimes, more than one target gene containing a hypermutated variable repeat (VR) can be found in phage DGRs. The role of mutagenesis of two functionally different genes is unclear. In this study, several phage genomes that contain DGRs with two target genes were found in the gut virome of healthy volunteer. Bioinformatics analysis of these genes indicated that they encode proteins with different topology; however, both proteins contain the C-type lectin (C-lec) domain with a hypermutated beta-hairpin on its surface. One of the target proteins belongs to a new family of proteins with a specific topology: N-terminal C-lec domain followed by one or more immunoglobulin domains. Proteins from the new family were named tentaclins after TENTACLe+proteIN. The genes encoding such proteins were found in the genomes of prophages and phages from the gut metagenomes. We hypothesized that tentaclins are involved in binding either to bacterial receptors or intestinal/immune cells.

Escherichia coli causes several infections like intestinal diarrhea, urinary tract infections, and pneumonia, which are difficult to treat due to the emergence of antimicrobial resistance. The World Health Organisation (WHO) declared carbapenem-resistant E. coli a critical pathogen and called for the development of new antimicrobial agents. Phage therapy, a century-old technique, has been revitalised recently with many successful applications against multi-drug resistant infections. As such, phage therapy is considered one of the most effective alternatives or adjuvants to antibiotics and is also effective in treating multidrug-resistant (MDR) bacterial infections. However, few phages that can kill pathogenic E. coli strains from Southeast Asia have been studied at a molecular level, although the burden of MDR, particularly carbapenem resistance, is high in this region. In this study, three closely related obligately virulent Escherichia phages (øEc_Makalu_001, øEc_Makalu_002, and øEc_Makalu_003) that could infect uropathogenic E. coli were isolated from sewage samples and characterized using morphological as well as sequence-based analysis. Further, a comparative genomic and phylogenetic analysis was done to predict the functional genes and evolutionary relationships. Electron microscopy and genome-based classification revealed that all three phages belonged Krischvirus genus of Straboviridae family. One-step growth curve showed that the latent period of the phages ranged from 15-20 min, the outbreak period was about 50 min, and the burst size ranged between 74-127 PFU/bacterium. Moreover, the phages could tolerate a pH range of 6 to 9 and a temperature range of 25-37°C for up to 180 minutes without significant loss of phage viability. Spotting the purified phages in different clinical isolates showed a broad host-range of isolated Escherichia phages and could lyse up to 30% of the tested pathogenic clinical isolates, including an intra-genus isolate of Klebsiella pneumoniae. The genome organization of all three phages was almost identical and similar to T4-like phage with a full-length genome of ~163 kb. Around 284 coding sequences (CDS) were predicted in each phage, of which only 40% were functional with an average gene length of 951 bp. The coding density in all phages was approximately 95%, while the gene density was 1.73 gene/kbp. Putative lysin, holin, endolysin, and spanin genes were found in the genomes of all three phages, resembling that of T4-like phages implying their phylogenetic relatedness. Furthermore, various in silico sequence analysis tools confirmed that all three phages were strictly virulent with functional lysis modules but devoid of any known virulence or toxin genes, integron-associated genes and antimicrobial-resistance (AMR) genes. In summary, pre-clinical experimental analysis and exploration of genomic features suggest that all three phages may be suitable candidates for therapeutic applications against uropathogenic E. coli.