Project description:Bacteriophage (phage) are viruses that can kill bacteria, but also mediate gene transfer for bacterial evolution. The telomere phages are a curious form using telomere-like structures to replicate their genomes as linear extrachromosomal elements. Here we find that telomere phages are widely distributed in bacteria, being highly prevalent in Klebsiella species. We established a model system to investigate telomere phage biology and find only a small set of phage proteins are expressed in phage-host cells, including a toxin – telocin - that kills other Klebsiella strains. We identify and validate other telocins in the genomes of other, widespread Klebsiella telomere phages. Thus, telomere phages are widespread elements encoding diverse antibacterial weapons and we discuss the prospect of using telocins for precision editing of microbial populations.
Project description:Phage therapy is a therapeutic approach to treat multidrug resistant infections that employs lytic bacteriophages (phages) to eliminate bacteria. Despite the abundant evidence for its success as an antimicrobial in Eastern Europe, there is scarce data regarding its effects on the human host. Here, we aimed to understand how lytic phages interact with cells of the airway epithelium, the tissue site that is colonized by bacterial biofilms in numerous chronic respiratory disorders. Using a panel of Pseudomonas aeruginosa phages and human airway epithelial cells derived from a person with cystic fibrosis, we determined that interactions between phages and epithelial cells depend on specific phage properties as well as physiochemical features of the microenvironment. Although poor at internalizing phages, the airway epithelium responds to phage exposure by changing its transcriptional profile and secreting antiviral and proinflammatory cytokines that correlate with specific phage families. Overall, our findings indicate that mammalian responses to phages are heterogenous and could potentially alter the way that respiratory local defenses aid in bacterial clearance during phage therapy. Thus, besides phage receptor specificity in a particular bacterial isolate, the criteria to select lytic phages for therapy should be expanded to include mammalian cell responses.
Project description:Virulent bacteriophages (or phages) are viruses that specifically infect and lyse a bacterial host. When multiple phages co-infect a bacterial host, the extent of lysis, dynamics of bacteria-phage and phage-phage interactions are expected to vary. The objective of this study is to identify the factors influencing the interaction of two virulent phages with different Pseudomonas aeruginosa growth states (planktonic, an infected epithelial cell line, and biofilm) by measuring the bacterial time-kill and individual phage replication kinetics. A single administration of phages effectively reduced P. aeruginosa viability in planktonic conditions and infected human lung cell cultures, but phage-resistant variants subsequently emerged. In static biofilms, the phage combination displayed initial inhibition of biofilm dispersal, but sustained control was achieved only by combining phages and meropenem antibiotic. In contrast, adherent biofilms showed tolerance to phage and/or meropenem, suggesting a spatiotemporal variation in the phage-bacterial interaction. The kinetics of adsorption of each phage to P. aeruginosa during single- or co-administration were comparable. However, the phage with the shorter lysis time depleted bacterial resources early and selected a specific nucleotide polymorphism that conferred a competitive disadvantage and cross-resistance to the second phage. The extent and strength of this phage-phage competition and genetic loci conferring phage resistance, are, however, P. aeruginosa genotype dependent. Nevertheless, adding phages sequentially resulted in their unimpeded replication with no significant increase in bacterial host lysis. These results highlight the interrelatedness of phage-phage competition, phage resistance and specific bacterial growth state (planktonic/biofilm) in shaping the interplay among P. aeruginosa and virulent phages.
Project description:Purified phage was used to prevent tumor growth in a mouse model of bacteria aggravated-colorectal cancer. Composite E. coli phage or vehicle control was added to the drinking water of specific pathogen free (SPF) APCmin mice and animals were colonized with E.coli NC101. APCmin mice displayed no overall difference in the number of tumors that formed within the small intestine, however colonization with E. coli NC101 accelerated the growth of tumors resulting in a significant increase in large tumor formation. Importantly, bacteriophage treatment of AIEC colonized APCmin animals significantly reduced E. coli colonization.
Project description:This study analysed the temporal transcriptional response of L. lactis UC509.9 undergoing infection with either Tuc2009 or c2, representing phages of two different species (P335 and c2, respectively) of the family Siphoviridae. For the first time, to our knowledge, both DNA microarrays of the host and high resolution tiling arrays of each phage were used provide corresponding data sets of the entire transcriptome at various points post-infection.
Project description:The Escherichia coli strain Nissle 1917 (EcN) is used as a probiotic for the treatment of certain gastrointestinal diseases in several European and non-European countries. In vitro studies showed EcN to efficiently inhibit the production of Shiga toxin (Stx) by Stx producing E. coli (STEC) such as Enterohemorrhagic E. coli (EHEC). The occurrence of the latest EHEC serotype (O104:H4) responsible for the great outbreak in 2011 in Germany was due to the infection of an enteroaggregative E. coli by a Stx 2-encoding lambdoid phage turning this E. coli into a lysogenic and subsequently into a Stx producing strain. Since EHEC infected persons are not recommended to be treated with antibiotics, EcN might be an alternative medication. However, because a harmless E. coli strain might be converted into a Stx-producer after becoming host to a stx encoding prophage, we tested EcN for stx-phage genome integration. Our experiments revealed the resistance of EcN towards not only stx-phages but also against the lambda phage. This resistance was not based on the lack of or by mutated phage receptors. Rather the expression of certain genes (superinfection exclusion B (sieB) and a phage repressor (pr) gene) of a defective prophage of EcN was involved in the complete resistance of EcN to infection by the stx- and lambda phage. Obviously, EcN cannot be turned into a Stx producer. Furthermore, we observed EcN to inactivate phages and thereby to protect E. coli K-12 strains against infection by stx- as well as lambda-phages. Inactivation of lambda-phages was due to binding of lambda-phages to LamB of EcN whereas inactivation of stx-phages was caused by a thermostable protein of EcN. These properties together with its ability to inhibit Stx production make EcN a good candidate for the prevention of illness caused by EHEC and probably for the treatment of already infected people.
Project description:This study analysed the temporal transcriptional response of L. lactis UC509.9 undergoing infection with either Tuc2009 or c2, representing phages of two different species (P335 and c2, respectively) of the family Siphoviridae. For the first time, to our knowledge, both DNA microarrays of the host and high resolution tiling arrays of each phage were used provide corresponding data sets of the entire transcriptome at various points post-infection. DNA microarrays containing oligonucleotide primers representing each of the 2066 annotated genes on the genome of L. lactis UC509.9 (Genbank accession number: CP003157), in addition to complete genome tiling arrays of bacteriophages Tuc2009 NC_002703) and C2 (NC_001706) at 4 bp resolution, were designed using eArray (https://earray.chem.agilent.com/earray/) and ChipD (http://www.ncbi.nlm.nih.gov/pubmed/20529880) and obtained from Agilent Technologies (Palo Alto, CA). For sample collection, pre-warmed GM17 (30 M-BM-0C) was inoculated with 2 % of an overnight culture of L. lactis UC509.9. This was grown at 30 M-BM-0C under static conditions to an OD600 of 0.13 at which point CaCl2 was added to a final concentration of 10 mM. The culture was further incubated for 10 min to allow equilibration. At this point, the culture was split into two equal volumes. To one, phage (either C2 or Tuc2009) in TBT buffer (100 mM Tris pH 7.5, 100 mM NaCl, 10 mM MgCl2), was added to a final multiplicity of infection (MOI) of 5. To the other, acting as control, a corresponding amount of TBT buffer without phage was added. Samples (60 ml) were collected at 2, 5, 10, 15, 25, 35 and, in the case of Tuc2009 only, 45 min post infection (p.i.) by centrifugation. Pellets were flash frozen in a -80 M-BM-0C EtOH bath. Samples were then maintained at -80 M-BM-0C until further processing and analysis.