The host factor requirements of phages and mechanisms of mutational phage insensitivity must be characterized for rational design of phage cocktails. To characterize host dependencies of two novel ...Escherichia coli phages, the T1-like siphophage LL5 and the V5-like myophage LL12, forward genetic screens were conducted against the Keio collection, a library of single non-essential gene deletions in E. coli str. BW25113. These screens and subsequent experiments identified genes required by phages LL5 and LL12. 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 additional genes encoding cytoplasmic chaperones, PpiB and SecB, were found to be required for efficient propagation of phage LL5, but not LL12. This screening approach may be useful for identifying host factors dependencies of phages, which would provide valuable information for their potential use as therapeutics and for phage engineering.
The bacterium Caulobacter crescentus is a popular model for the study of cell cycle regulation and senescence. The large prolate siphophage phiCbK has been an important tool in C. crescentus biology, ...and has been studied in its own right as a model for viral morphogenesis. Although a system of some interest, to date little genomic information is available on phiCbK or its relatives.
Five novel phiCbK-like C. crescentus bacteriophages, CcrMagneto, CcrSwift, CcrKarma, CcrRogue and CcrColossus, were isolated from the environment. The genomes of phage phiCbK and these five environmental phage isolates were obtained by 454 pyrosequencing. The phiCbK-like phage genomes range in size from 205 kb encoding 318 proteins (phiCbK) to 280 kb encoding 448 proteins (CcrColossus), and were found to contain nonpermuted terminal redundancies of 10 to 17 kb. A novel method of terminal ligation was developed to map genomic termini, which confirmed termini predicted by coverage analysis. This suggests that sequence coverage discontinuities may be useable as predictors of genomic termini in phage genomes. Genomic modules encoding virion morphogenesis, lysis and DNA replication proteins were identified. The phiCbK-like phages were also found to encode a number of intriguing proteins; all contain a clearly T7-like DNA polymerase, and five of the six encode a possible homolog of the C. crescentus cell cycle regulator GcrA, which may allow the phage to alter the host cell's replicative state. The structural proteome of phage phiCbK was determined, identifying the portal, major and minor capsid proteins, the tail tape measure and possible tail fiber proteins. All six phage genomes are clearly related; phiCbK, CcrMagneto, CcrSwift, CcrKarma and CcrRogue form a group related at the DNA level, while CcrColossus is more diverged but retains significant similarity at the protein level.
Due to their lack of any apparent relationship to other described phages, this group is proposed as the founding cohort of a new phage type, the phiCbK-like phages. This work will serve as a foundation for future studies on morphogenesis, infection and phage-host interactions in C. crescentus.
Klebsiella pneumoniae is a Gram-negative pathogen frequently associated with antibiotic-resistant nosocomial infections. Bacteriophage therapy against K. pneumoniae may be possible to combat these ...infections. The following describes the complete genome sequence and key features of the pseudo-T-even K. pneumoniae carbapenemase (KPC)-producing K. pneumoniae myophage Miro.
Klebsiella pneumoniae is a leading cause of nosocomial infections in the United States. Due to the emergence of multidrug-resistant strains, phages targeting K. pneumoniae may be a useful alternative ...against this pathogen. Here, we announce the complete genome of K. pneumoniae pseudo-T-even myophage Matisse and describe its features.
Enterotoxigenic Escherichia coli (ETEC) is one of the leading causes of diarrhea in developing countries. Bacteriophage therapy has the potential to aid in the prevention and treatment of ...ETEC-related illness. To that end, we present here the complete genome of ETEC siphophage Seurat and describe its major features.
Klebsiella pneumoniae is a Gram-negative bacterium in the family Enterobacteriaceae. It is associated with numerous nosocomial infections, including respiratory and urinary tract infections in ...humans. The following reports the complete genome sequence of K. pneumoniae carbapenemase-producing K. pneumoniae T1-like siphophage Sushi and describes its major features.
Chronic liver disease due to alcohol-use disorder contributes markedly to the global burden of disease and mortality
. Alcoholic hepatitis is a severe and life-threatening form of alcohol-associated ...liver disease. The gut microbiota promotes ethanol-induced liver disease in mice
, but little is known about the microbial factors that are responsible for this process. Here we identify cytolysin-a two-subunit exotoxin that is secreted by Enterococcus faecalis
-as a cause of hepatocyte death and liver injury. Compared with non-alcoholic individuals or patients with alcohol-use disorder, patients with alcoholic hepatitis have increased faecal numbers of E. faecalis. The presence of cytolysin-positive (cytolytic) E. faecalis correlated with the severity of liver disease and with mortality in patients with alcoholic hepatitis. Using humanized mice that were colonized with bacteria from the faeces of patients with alcoholic hepatitis, we investigated the therapeutic effects of bacteriophages that target cytolytic E. faecalis. We found that these bacteriophages decrease cytolysin in the liver and abolish ethanol-induced liver disease in humanized mice. Our findings link cytolytic E. faecalis with more severe clinical outcomes and increased mortality in patients with alcoholic hepatitis. We show that bacteriophages can specifically target cytolytic E. faecalis, which provides a method for precisely editing the intestinal microbiota. A clinical trial with a larger cohort is required to validate the relevance of our findings in humans, and to test whether this therapeutic approach is effective for patients with alcoholic hepatitis.
Widespread antibiotic use in clinical medicine and the livestock industry has contributed to the global spread of multidrug-resistant (MDR) bacterial pathogens, including
We report on a method used ...to produce a personalized bacteriophage-based therapeutic treatment for a 68-year-old diabetic patient with necrotizing pancreatitis complicated by an MDR
infection. Despite multiple antibiotic courses and efforts at percutaneous drainage of a pancreatic pseudocyst, the patient deteriorated over a 4-month period. In the absence of effective antibiotics, two laboratories identified nine different bacteriophages with lytic activity for an
isolate from the patient. Administration of these bacteriophages intravenously and percutaneously into the abscess cavities was associated with reversal of the patient's downward clinical trajectory, clearance of the
infection, and a return to health. The outcome of this case suggests that the methods described here for the production of bacteriophage therapeutics could be applied to similar cases and that more concerted efforts to investigate the use of therapeutic bacteriophages for MDR bacterial infections are warranted.
Enterotoxigenic Escherichia coli is a multidrug-resistant bacterium that is well known for its ability to cause diarrhea in humans. Bacteriophages may be used to treat clinical cases involving ...bacterial dysentery. Here, we present the complete genome sequence of an enterotoxigenic E. coli phage, Pollock, an N4-like podophage.
Electrophilic trisubstituted ethylenes, ring-disubstituted ethyl 2-cyano-3-phenyl-2-propenoates, RPhCH˭C(CN)CO
2
C
2
H
5
(where R is 3-Br-4-CH
3
O, 5-Br-2-CH
3
O, 3-F-2- CH
3
, 3-F-4-CH
3
, 4-F-2-CH
...3
, 4-F-3-CH
3
, 5-F-2-CH
3
, 2-Cl-5-NO
2
, 2-Cl-6-NO
2
, 4-Cl-3- NO
2
) were prepared and copolymerized with styrene. The monomers were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-disubstituted benzaldehydes and ethyl cyanoacetate, and characterized by CHN analysis, IR,
1
H and
13
C-NMR. All the ethylenes were copolymerized with styrene (M
1
) in solution with radical initiation (ABCN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR,
1
H and
13
C-NMR. The order of relative reactivity (1/r
1
) for the monomers is 5-Br-2-CH
3
O (1.02) > 4-Cl-3-NO
2
(0.93) > 3-F-4-CH
3
(0.81) > 2-Cl-6-NO
2
(0.77) > 2-Cl-5-NO
2
(0.71) > 3-Br-4-CH
3
O (0.66) > 4-F-3-CH
3
(0.60) > 3-F-2-CH
3
(0.38) > 4-F-2-CH
3
(0.31) > 5-F-2-CH
3
(0.16). Relatively high T
g
of the copolymers in comparison with that of polystyrene indicates a decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 250-500°C range with residue (2-26% wt.), which then decomposed in the 500-800°C range.
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