scholarly journals Two new plasmid post-segregational killing mechanisms for the implementation of synthetic gene networks inE. coli

2018 ◽  
Author(s):  
Alex J H Fedorec ◽  
Tanel Ozdemir ◽  
Anjali Doshi ◽  
Luca Rosa ◽  
Oscar Velazquez ◽  
...  
Keyword(s):  
Real World ◽  
Gene Networks ◽  
Plasmid Stability ◽  
Industrial Biotechnology ◽  
Bacterial Cells ◽  
Two Component System ◽  
Synthetic Gene Networks ◽  
Therapeutic Setting

AbstractPlasmids are the workhorse of both industrial biotechnology and synthetic biology, but ensuring they remain in bacterial cells is a challenge. Antibiotic selection, commonly used in the laboratory, cannot be used to stabilise plasmids in most real-world applications, and inserting dynamical gene networks into the genome is difficult. Plasmids have evolved several mechanisms for stability, one of which, post-segregational killing (PSK), ensures that plasmid-free cells do not grow or survive. Here we demonstrate the plasmid-stabilising capabilities of the axe/txe two component system and the microcin-V system in the probiotic bacteriaEscherichia coliNissle 1917 and show they can outperform the hok/sok system commonly used in biotechnological applications. Using plasmid stability assays, automated flow cytometry analysis, mathematical models and Bayesian statistics we quantified plasmid stabilityin vitro. Further, we used anin vivomouse cancer model to demonstrate plasmid stability in a real-world therapeutic setting. These new PSK systems, plus the developed Bayesian methodology, will have wide applicability in clinical and industrial biotechnology.

scholarly journals ssDNA recombineering boosts in vivo evolution of nanobodies displayed on bacterial surfaces

2021 ◽  
Author(s):  
Yamal Al-ramahi ◽  
Akos Nyerges ◽  
Yago Margolles ◽  
Lidia Cerdán ◽  
Gyorgyi Ferenc ◽  
...  
Keyword(s):  
Bacterial Genome ◽  
Industrial Biotechnology ◽  
Bacterial Cells ◽  
E Coli ◽  
Immunomagnetic Capture ◽  
Bacterial Surfaces ◽  
Potential Applications ◽  
Novel Target

SUMMARYIn vivo evolution of antibodies facilitates emergence of novel target specificities from pre-existing clones. In this work we show how mutagenic ssDNA recombineering of camel-derived nanobodies encoded in a bacterial genome enables clonal hyper-diversification and the rise of new properties. As a proof-of-principle we used a nanobody recognizing the antigen TirM from enterohaemorrhagic E. coli (EHEC) and evolved it towards the otherwise not recognized TirM antigen from enteropathogenic E. coli (EPEC). To this end, E. coli cells displaying on their surface this nanobody fused to the intimin outer membrane anchor domain were subjected to multiple rounds of mutagenic ssDNA recombineering targeted to the CDR1, CDR2 and CDR3 regions of its genomically encoded VHH sequence. Binders to the new antigen (EPEC TirM) were then selected upon immunomagnetic capture of bacteria bearing the corresponding nanobody variants. As a result, several modified nanobodies were identified which maintained recognition of EHEC TirM but acquired the ability to bind the new antigen with high affinity (Kd ~20 nM). The results highlight the power of combining evolutionary properties of bacteria in vivo with oligonucleotide synthesis in vitro for the sake of focusing diversification to specific segments of a gene (or protein thereof) of interest. Our experimental workflow empowers the evolution of nanobodies displayed on the surface of bacterial cells for a large number of potential applications in medical and industrial biotechnology.

scholarly journals In Vivo Entombment of Bacteria and Fungi during Calcium Oxalate, Brushite and Struvite Urolithiasis

Kidney360 ◽  
2020 ◽  
pp. 10.34067/KID.0006942020
Author(s):  
Jessica J. Saw ◽  
Mayandi Sivaguru ◽  
Elena M. Wilson ◽  
Yiran Dong ◽  
Robert A. Sanford ◽  
...  
Keyword(s):  
Calcium Oxalate ◽  
Stone Formation ◽  
Human Kidney ◽  
Rrna Gene ◽  
Bacterial Cells ◽  
Stone Formers ◽  
Bacteria And Fungi ◽  
Struvite Stones

Background: Human kidney stones form via repeated events of mineral precipitation, partial dissolution and reprecipitation, which are directly analogous to similar processes in other natural and man-made environments where resident microbiomes strongly influence biomineralization. High-resolution microscopy and high-fidelity metagenomic (microscopy-to-omics) analyses, applicable to all forms of biomineralization, have been applied to assemble definitive evidence of in vivo microbiome entombment during urolithiasis. Methods: Stone fragments were collected from a randomly chosen cohort of 20 patients using standard percutaneous nephrolithotomy (PCNL). Fourier transform infrared (FTIR) spectroscopy indicated that 18 of these patients were calcium oxalate (CaOx) stone formers, while one patient each formed brushite and struvite stones. This apportionment is consistent with global stone mineralogy distributions. Stone fragments from 7 of these 20 patients (5 CaOx, 1 brushite and 1 struvite) were thin sectioned and analyzed using brightfield (BF), polarization (POL), confocal, superresolution autofluorescence (SRAF) and Raman techniques. DNA from remaining fragments, grouped according to each of the 20 patients, were analyzed with amplicon sequencing of 16S rRNA gene sequences (V1-V3, V3-V5) and internal transcribed spacer (ITS1, ITS2) regions. Results: Bulk entombed DNA was sequenced from stone fragments in 11 of the 18 CaOx patients, as well as the brushite and struvite patients. These analyses confirmed the presence of an entombed low-diversity community of bacteria and fungi, including Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria, and Aspergillus niger. Bacterial cells ~1  µm in diameter were also optically observed to be entombed and well-preserved in amorphous hydroxyapatite spherules and fans of needle-like crystals of brushite and struvite. Conclusions: These results indicate a microbiome is entombed during in vivo CaOx stone formation. Similar processes are implied for brushite and struvite stones. This evidence lays the groundwork for future in vitro and in vivo experimentation to determine how the microbiome may actively and/or passively influence kidney stone biomineralization.

scholarly journals IN VITRO ANTIOXIDANT AND IN VIVO ANTIDIABETIC ACTIVITY OF TWO POTENTIAL PROBIOTIC ENTEROCOCCUS SPP. ON ALLOXAN-INDUCED DIABETIC RATS

2021 ◽  
pp. 94-98
Author(s):  
KAMNI RAJPUT ◽  
RAMESH CHANDRA DUBEY
Keyword(s):  
Diabetic Rats ◽  
Antidiabetic Activity ◽  
Control Group ◽  
Albino Rats ◽  
Bacterial Cells ◽  
Bacterial Strains ◽  
Animal Group ◽  
Enterococcus Spp

Objective: In vitro antioxidant activity, in vivo antidiabetic property and intestinal attachment by two potential probiotic bacterial strains, namely, Enterococcus faecium and Enterococcus hirae were studied using albino rats. Methods: Antioxidant the activity was assessed using 2,2-Diphenyl-1-picrylhydrazyl radicals scavenging assay. Alloxan was administered intraperitoneally to induce diabetic conditions in experimental rats. Animals were treated with oral administration of Enterococcus spp., such as E. faecium, and E. hirae isolated from goat and sheep milk. The control animal group received normal saline for the same days. Glibenclamide drug was used as a positive control against probiotic bacterial cells. Results: However, administration of probiotic bacterial strains E. faecium and E. hirae, in albino rats significantly (p<0.05) at varying doses lowered blood glucose levels in diabetic rats as compared to the diabetic control group. Both the species of Enterococcus increased the bodyweight of experimental rats. However, E. faecium was the best antidiabetic strain having the antioxidant activities also in comparison to E. hirae. The attachment of probiotic bacterial cells E. faecium on the rat’s intestine wall against pathogens was examined. Furthermore, E. faecium showed its aggregation with pathogens by attachment of the intestines of albino rats. This showed that both the bacterial strains exhibited in vivo antidiabetic effect. Conclusion: The results of this study showed that probiotic bacteria possess antioxidant, antidiabetic activities, and attachment of intestine.

scholarly journals Assessment of Minocycline and Polymyxin B Combination against Acinetobacter baumannii

2015 ◽  
Vol 59 (5) ◽  
pp. 2720-2725 ◽  
Author(s):  
Dana R. Bowers ◽  
Henry Cao ◽  
Jian Zhou ◽  
Kimberly R. Ledesma ◽  
Dongxu Sun ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Clinical Utility ◽  
Efflux Pump ◽  
Polymyxin B ◽  
Intracellular Concentration ◽  
Bacterial Cells ◽  
Efflux Pump Inhibitor ◽  
Content Type

ABSTRACTAntimicrobial resistance amongAcinetobacter baumanniiis increasing worldwide, often necessitating combination therapy. The clinical utility of using minocycline with polymyxin B is not well established. In this study, we investigated the activity of minocycline and polymyxin B against 1 laboratory isolate and 3 clinical isolates ofA. baumannii. Minocycline susceptibility testing was performed with and without an efflux pump inhibitor, phenylalanine-arginine β-naphthylamide (PAβN). The intracellular minocycline concentration was determined with and without polymyxin B (0.5 μg/ml). Time-kill studies were performed over 24 h using approximately 106CFU/ml of each strain with clinically relevant minocycline concentrations (2 μg/ml and 8 μg/ml), with and without polymyxin B (0.5 μg/ml). Thein vivoefficacy of the combination was assessed in a neutropenic murine pneumonia model. Infected animals were administered minocycline (50 mg/kg), polymyxin B (10 mg/kg), or both to achieve clinically equivalent exposures in humans. A reduction in the minocycline MIC (≥4×) was observed in the presence of PAβN. The intracellular concentration andin vitrobactericidal effect of minocycline were both enhanced by polymyxin B. With 2 minocycline-susceptible strains, the bacterial burden in lung tissue at 24 h was considerably reduced by the combination compared to monotherapy with minocycline or polymyxin B. In addition, the combination prolonged survival of animals infected with a minocycline-susceptible strain. Polymyxin B increased the intracellular concentration of minocycline in bacterial cells and enhanced the bactericidal activity of minocycline, presumably due to efflux pump disruption. The clinical utility of this combination should be further investigated.

scholarly journals Cre/LoxP-HBV plasmids generating recombinant covalently closed circular DNA genome upon transfection

2020 ◽  
Author(s):  
Robert L. Kruse ◽  
Xavier Legras ◽  
Mercedes Barzi
Keyword(s):  
Plasmid Dna ◽  
Plasmid Stability ◽  
Intron Insertion ◽  
Circular Dna ◽  
Immunodeficient Mice ◽  
New Therapies ◽  
Covalently Closed Circular Dna ◽  
Dna Silencing

AbstractNew therapies against hepatitis B virus (HBV) require the elimination of covalently closed circular DNA (cccDNA), the episomal HBV genome. HBV plasmids containing an overlength 1.3-mer genome and bacterial backbone (pHBV1.3) are used in many different models, but do not replicate the unique features of cccDNA. Since the stable cccDNA pool is a barrier to HBV eradication in patients, we developed a recombinant circular HBV genome (rcccDNA) to mimic the cccDNA using Cre/LoxP technology. We validated four LoxP insertion sites into the HBV genome using hydrodynamic tail vein injection into murine liver, demonstrating high levels of HBV surface antigen (HBsAg) and HBV DNA expression with rcccDNA formation. HBsAg expression from rcccDNA was >30,000 ng/mL over 78 days, while HBsAg-expression from pHBV1.3 plasmid DNA declined from 2,753 ng/mL to 131 ng/mL over that time in immunodeficient mice (P<0.001), reflective of plasmid DNA silencing. We then cloned Cre-recombinase in cis on the LoxP-HBV plasmids, achieving plasmid stability in bacteria with intron insertion into Cre and demonstrating rcccDNA formation after transfection in vitro and in vivo. These cis-Cre/LoxP-HBV plasmids were then used to create HBx-mutant and GFP reporter plasmids to further probe cccDNA biology and antiviral strategies against cccDNA. Overall, we believe these auto-generating rcccDNA plasmids will be of great value to model cccDNA for testing new therapies against HBV infection.

scholarly journals Non-Lytic Antibacterial Peptides That Translocate Through Bacterial Membranes to Act on Intracellular Targets

2019 ◽  
Vol 20 (19) ◽  
pp. 4877 ◽  
Author(s):  
Marlon H. Cardoso ◽  
Beatriz T. Meneguetti ◽  
Bruna O. Costa ◽  
Danieli F. Buccini ◽  
Karen G. N. Oshiro ◽  
...  
Keyword(s):  
Cell Wall ◽  
Protein Synthesis ◽  
Pathogenic Bacteria ◽  
Biological Properties ◽  
Antibacterial Peptides ◽  
Bacterial Cells ◽  
Bacterial Membranes ◽  
Intracellular Targets

The advent of multidrug resistance among pathogenic bacteria has attracted great attention worldwide. As a response to this growing challenge, diverse studies have focused on the development of novel anti-infective therapies, including antimicrobial peptides (AMPs). The biological properties of this class of antimicrobials have been thoroughly investigated, and membranolytic activities are the most reported mechanisms by which AMPs kill bacteria. Nevertheless, an increasing number of works have pointed to a different direction, in which AMPs are seen to be capable of displaying non-lytic modes of action by internalizing bacterial cells. In this context, this review focused on the description of the in vitro and in vivo antibacterial and antibiofilm activities of non-lytic AMPs, including indolicidin, buforin II PR-39, bactenecins, apidaecin, and drosocin, also shedding light on how AMPs interact with and further translocate through bacterial membranes to act on intracellular targets, including DNA, RNA, cell wall and protein synthesis.

scholarly journals TSPphg Lysin from the Extremophilic Thermus Bacteriophage TSP4 as a Potential Antimicrobial Agent against Both Gram-Negative and Gram-Positive Pathogenic Bacteria

Viruses ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 192 ◽  
Author(s):  
Feng Wang ◽  
Xinyu Ji ◽  
Qiupeng Li ◽  
Guanling Zhang ◽  
Jiani Peng ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Pathogenic Bacteria ◽  
Infection Model ◽  
Bacterial Cells ◽  
Skin Damage ◽  
Gram Positive ◽  
Antibiotic Resistant ◽  
Gram Negative

New strategies against antibiotic-resistant bacterial pathogens are urgently needed but are not within reach. Here, we present in vitro and in vivo antimicrobial activity of TSPphg, a novel phage lysin identified from extremophilic Thermus phage TSP4 by sequencing its whole genome. By breaking down the bacterial cells, TSPphg is able to cause bacteria destruction and has shown bactericidal activity against both Gram-negative and Gram-positive pathogenic bacteria, especially antibiotic-resistant strains of Klebsiella pneumoniae, in which the complete elimination and highest reduction in bacterial counts by greater than 6 logs were observed upon 50 μg/mL TSPphg treatment at 37 °C for 1 h. A murine skin infection model further confirmed the in vivo efficacy of TSPphg in removing a highly dangerous and multidrug-resistant Staphylococcus aureus from skin damage and in accelerating wound closure. Together, our findings may offer a therapeutic alternative to help fight bacterial infections in the current age of mounting antibiotic resistance, and to shed light on bacteriophage-based strategies to develop novel anti-infectives.

scholarly journals Adoptive transfer of anti-cytomegalovirus effect of interleukin-2- activated bone marrow: potential application in transplantation

Blood ◽  
1991 ◽  
Vol 78 (3) ◽  
pp. 720-727 ◽  
Author(s):  
R Agah ◽  
BS Charak ◽  
V Chen ◽  
A Mazumder
Keyword(s):  
Bone Marrow ◽  
Interleukin 2 ◽  
Murine Cytomegalovirus ◽  
Mcmv Infection ◽  
Murine Bone Marrow ◽  
Therapeutic Setting ◽  
Infected Cells ◽  
Novel Strategy

Abstract This work is a continuation of our studies that showed that interleukin- 2 (IL-2)-activated murine bone marrow (ABM) cells have potent cytotoxic potential against murine cytomegalovirus (MCMV)-infected targets in vitro, without loss of reconstitutive ability in vivo. Our data show that ABM cells lyse the MCMV-infected cells in vitro, at both acute and chronic stages of infection; this lysis is specific for the MCMV- infected cells. ABM cells supplemented with IL-2 therapy virtually eradicated the viral infection and prolonged the survival of MCMV- infected Balb/c mice, whether or not they were immunocompromised by irradiation (P less than .001 in both situations). Efficacy of ABM cells alone or IL-2 alone was less than the combination of ABM cells and IL-2. The efficacy of combination treatment with ABM cells and IL-2 in improving the survival of MCMV-infected mice was comparable, whether used in a preventive or a therapeutic setting. Therapy with ABM plus IL- 2 also prevented the reactivation of chronic MCMV infection after irradiation. Preliminary findings indicate that Thy-1+ and asialo GM1+ cells limited the MCMV proliferation by approximately 30% and 80%, respectively, while BM macrophages limited the proliferation of MCMV by 100%. These results suggest that BM transplantation (BMT) with ABM cells followed by IL-2 therapy may constitute a novel strategy to improve the host resistance against cytomegalovirus infection after BMT.

scholarly journals The antibacterial activity and toxin production control of bee venom in mouse MRSA pneumonia model

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Ryong Kong ◽  
Young-Seob Lee ◽  
Dam-Hee Kang ◽  
Shu Wang ◽  
Qianqian Li ◽  
...  
Keyword(s):  
Production Control ◽  
Antimicrobial Effect ◽  
Toxin Production ◽  
Bee Venom ◽  
Dilution Method ◽  
Bacterial Cells ◽  
Related Gene ◽  
Mrsa Infection

Abstract Background The current antimicrobial therapy is still important for the treatment of pneumonia due to MRSA infection, but there are some limitations, including the route of administration, side effect profile, and increased microbial resistance patterns. Therefore, we investigated whether BV, which shows a strong antimicrobial effect against MRSA, would be effective in a pneumonia model. Methods In vitro, we checked MIC, qRT-PCR, western blot, ELISA, LDH-assay. In vivo, we checked survival rate, gross pathological change, histopathology, lung bacterial clearance assay, and the expression of inflammatory related gene. Results The minimum inhibitory concentration of BV against MRSA is 15.6 μg/ml by broth dilution method. The production of toxins and related gene were reduced by BV in MRSA. The secretion of cytokines were decreased by treatment with BV in 264.7 RAW macrophages stimulated by MRSA Also, BV protected A549 from pathogenicity of MRSA. Bee venom reduced the number of bacteria in the lungs and alleviated the symptoms of MRSA-induced pneumonia in mouse. Conclusion BV inhibited the virulence of the bacterium and the number of bacterial cells present in lung tissue, thereby alleviating the symptoms of pneumonia in mice. This study suggested that BV may be a candidate substance for the treatment of pneumonia caused by MRSA infection.

scholarly journals The Glucocorticoid Receptor in Cardiovascular Health and Disease

Cells ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1227 ◽  
Author(s):  
Liu ◽  
Zhang ◽  
Knight ◽  
Goodwin
Keyword(s):  
Glucocorticoid Receptor ◽  
Cardiovascular System ◽  
Gene Networks ◽  
Cardiovascular Health ◽  
Critical Role ◽  
Glucocorticoid Signaling ◽  
Health And Disease ◽  
Nuclear Receptor Family

The glucocorticoid receptor is a member of the nuclear receptor family that controls many distinct gene networks, governing various aspects of development, metabolism, inflammation, and the stress response, as well as other key biological processes in the cardiovascular system. Recently, research in both animal models and humans has begun to unravel the profound complexity of glucocorticoid signaling and convincingly demonstrates that the glucocorticoid receptor has direct effects on the heart and vessels in vivo and in vitro. This research has contributed directly to improving therapeutic strategies in human disease. The glucocorticoid receptor is activated either by the endogenous steroid hormone cortisol or by exogenous glucocorticoids and acts within the cardiovascular system via both genomic and non-genomic pathways. Polymorphisms of the glucocorticoid receptor are also reported to influence the progress and prognosis of cardiovascular disease. In this review, we provide an update on glucocorticoid signaling and highlight the critical role of this signaling in both physiological and pathological conditions of the cardiovascular system. With increasing in-depth understanding of glucocorticoid signaling, the future is promising for the development of targeted glucocorticoid treatments and improved clinical outcomes.

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