scholarly journals Double Recombinant Mycobacterium bovis BCG Strain for Screening of Primary and Rationale-Based Antimycobacterial Compounds

2013 ◽  
Vol 58 (3) ◽  
pp. 1389-1396 ◽  
Author(s):  
Vandana Singh ◽  
Rajesh Kumar Biswas ◽  
Bhupendra N. Singh
Keyword(s):  
Mycobacterium Bovis ◽  
Firefly Luciferase ◽  
Luciferase Reporter ◽  
Content Type ◽  
Wide Range ◽  
Firefly Luciferase Gene ◽  
Enhanced Expression ◽  
Reporter Strains ◽  
Double Recombinant ◽  
Dual Luciferase Reporter Assay

ABSTRACTConventional antimycobacterial screening involves CFU analysis, which poses a great challenge due to slow growth of mycobacteria. Recombinant strains carrying reporter genes under the influence of constitutive promoters allow rapid and wide screening of compounds but without revealing their modes of action. Reporter strains using pathway-specific promoters provide a better alternative but allow a limited screening of compounds interfering with only a particular metabolic pathway. This reduces these strains to merely a second-line screening system, as they fail to identify even the more potent compounds if they are not inhibiting the pathway of interest. In this study, we have generated a double recombinantMycobacterium bovisBCG strain carrying firefly andRenillaluciferase genes as two reporters under the control of a constitutive and an inducible mycobacterial promoter. The presence of dual reporters allows simultaneous expression and analysis of two reporter enzymes within a single system. The expression profile of the firefly luciferase gene, rendered by a constitutive mycobacterial promoter, coincides with the decline in bacterial growth in response to a wide range of antimycobacterial drugs, while the enhanced expression ofRenillaluciferase mirrors the selective induction of the reporter gene expression as a result of pathway-specific inhibition. Thus, the double recombinant strain allows the screening of both primary and rationally synthesized antimycobacterial compounds in a single assay. The inhibiting response of drugs was monitored with a dual-luciferase reporter assay which can be easily adapted in high-throughput mode.

scholarly journals Affordable Luciferase Reporter Assay for Cell-Based High-Throughput Screening

2012 ◽  
Vol 18 (4) ◽  
pp. 453-461 ◽  
Author(s):  
Ellen Siebring-van Olst ◽  
Christie Vermeulen ◽  
Renee X. de Menezes ◽  
Michael Howell ◽  
Egbert F. Smit ◽  
...  
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Firefly Luciferase ◽  
Luciferase Assay ◽  
Luciferase Reporter ◽  
Chemical Components ◽  
Simple Liquid ◽  
Luciferase Reporter Construct ◽  
Reagent Cost ◽  
Firefly Luciferase Gene

The firefly luciferase gene is commonly used in cell-based reporter assays. Convenient luciferase assay reagents for use in high-throughput screening (HTS) are commercially available. However, the high cost of these reagents is not within the means of some academic laboratories. Therefore, we set out to develop an affordable luciferase assay reagent applicable in an HTS format using simple liquid-handling steps. The reagent was homemade from individual chemical components and optimized for luminescence intensity and stability. We determined the minimal concentrations of the most expensive components, dithiothreitol (DTT) and D-luciferin, resulting in a total assay reagent cost of less than 1 cent per sample. Signal stability was maximized by omission of coenzyme A and reduction of DTT concentration. The assay was validated in a high-throughput setting using two cancer cell lines carrying a p53-dependent luciferase reporter construct and siRNAs modulating p53 transcriptional activity. Induction of p53 activity by silencing PPM1D or SYVN1 and reduction of p53 activity by silencing p53 remained constant over a 2-h measurement period, with good assay quality (Z′ factors mostly above 0.5). Hence, the luciferase assay described herein can be used for affordable reporter readout in cell-based HTS.

scholarly journals New Recombinant Mycobacterium bovis BCG Expression Vectors: Improving Genetic Control over Mycobacterial Promoters

2016 ◽  
Vol 82 (8) ◽  
pp. 2240-2246 ◽  
Author(s):  
Alex I. Kanno ◽  
Cibelly Goulart ◽  
Henrique K. Rofatto ◽  
Sergio C. Oliveira ◽  
Luciana C. C. Leite ◽  
...  
Keyword(s):  
Mycobacterium Bovis ◽  
Fluorescent Protein ◽  
Vaccine Development ◽  
Expression Vectors ◽  
Content Type ◽  
Expression Levels ◽  
Wide Range ◽  
Mycobacteriophage L5 ◽  
Green Fluorescent ◽  
Selection Of

ABSTRACTThe expression of many antigens, stimulatory molecules, or even metabolic pathways in mycobacteria such asMycobacterium bovisBCG orM. smegmatiswas made possible through the development of shuttle vectors, and several recombinant vaccines have been constructed. However, gene expression in any of these systems relied mostly on the selection of natural promoters expected to provide the required level of expression by trial and error. To establish a systematic selection of promoters with a range of strengths, we generated a library of mutagenized promoters through error-prone PCR of the strong PL5promoter, originally from mycobacteriophage L5. These promoters were cloned upstream of the enhanced green fluorescent protein reporter gene, and recombinantM. smegmatisbacteria exhibiting a wide range of fluorescence levels were identified. A set of promoters was selected and identified as having high (pJK-F8), intermediate (pJK-B7, pJK-E6, pJK-D6), or low (pJK-C1) promoter strengths in bothM. smegmatisandM. bovisBCG. The sequencing of the promoter region demonstrated that it was extensively modified (6 to 11%) in all of the plasmids selected. To test the functionality of the system, two different expression vectors were demonstrated to allow corresponding expression levels of theSchistosoma mansoniantigen Sm29 in BCG. The approach used here can be used to adjust expression levels for synthetic and/or systems biology studies or for vaccine development to maximize the immune response.

scholarly journals Population Structure of Mycobacterium bovis in Germany: a Long-Term Study Using Whole-Genome Sequencing Combined with Conventional Molecular Typing Methods

2020 ◽  
Vol 58 (11) ◽  
Author(s):  
Thomas A. Kohl ◽  
Katharina Kranzer ◽  
Sönke Andres ◽  
Thierry Wirth ◽  
Stefan Niemann ◽  
...  
Keyword(s):  
Population Structure ◽  
Whole Genome Sequencing ◽  
Genome Sequencing ◽  
Mycobacterium Bovis ◽  
Variable Number Tandem Repeat ◽  
Epidemiological Surveillance ◽  
Whole Genome ◽  
Content Type ◽  
Long Term Study ◽  
Wide Range

ABSTRACT Mycobacterium bovis is the primary cause of bovine tuberculosis (bTB) and infects a wide range of domestic animal and wildlife species and humans. In Germany, bTB still emerges sporadically in cattle herds, free-ranging wildlife, diverse captive animal species, and humans. In order to understand the underlying population structure and estimate the population size fluctuation through time, we analyzed 131 M. bovis strains from animals (n = 38) and humans (n = 93) in Germany from 1999 to 2017 by whole-genome sequencing (WGS), mycobacterial interspersed repetitive-unit–variable-number tandem-repeat (MIRU-VNTR) typing, and spoligotyping. Based on WGS data analysis, 122 out of the 131 M. bovis strains were classified into 13 major clades, of which 6 contained strains from both human and animal cases and 7 only strains from human cases. Bayesian analyses suggest that the M. bovis population went through two sharp anticlimaxes, one in the middle of the 18th century and another one in the 1950s. WGS-based cluster analysis grouped 46 strains into 13 clusters ranging in size from 2 to 11 members and involving strains from distinct host types, e.g., only cattle and also mixed hosts. Animal strains of four clusters were obtained over a 9-year span, pointing toward autochthonous persistent bTB infection cycles. As expected, WGS had a higher discriminatory power than spoligotyping and MIRU-VNTR typing. In conclusion, our data confirm that WGS and suitable bioinformatics constitute the method of choice to implement prospective molecular epidemiological surveillance of M. bovis. The population of M. bovis in Germany is diverse, with subtle, but existing, interactions between different host groups.

scholarly journals Staphylococcus aureus Cell Extract Transcription-Translation Assay: Firefly Luciferase Reporter System for Evaluating Protein Translation Inhibitors

2001 ◽  
Vol 45 (6) ◽  
pp. 1900-1904 ◽  
Author(s):  
Robert W. Murray ◽  
Earline P. Melchior ◽  
Jeanne C. Hagadorn ◽  
Keith R. Marotti
Keyword(s):  
Staphylococcus Aureus ◽  
Background Level ◽  
Protein Translation ◽  
Firefly Luciferase ◽  
Cell Extract ◽  
Luciferase Reporter ◽  
Translation System ◽  
Reporter System ◽  
Transcription Inhibitor ◽  
Firefly Luciferase Gene

ABSTRACT The promoter for the Staphylococcus aureus capsule polysaccharide synthesis gene (cap1A) was cloned in front of the firefly luciferase gene for use in a cell extractS. aureus transcription-translation system. The assay is rapid, reproducible, and sensitive and has a lower background level than the radiolabeled amino acid incorporation translation assays. We present data evaluating a transcription inhibitor and a number of protein translation inhibitors in this system.

scholarly journals IP-10 Is a Sensitive Biomarker of Antigen Recognition in Whole-Blood Stimulation Assays Used for the Diagnosis of Mycobacterium bovis Infection in African Buffaloes (Syncerus caffer)

2015 ◽  
Vol 22 (8) ◽  
pp. 974-978 ◽  
Author(s):  
Wynand J. Goosen ◽  
David Cooper ◽  
Michele A. Miller ◽  
Paul D. van Helden ◽  
Sven D. C. Parsons
Keyword(s):  
Mycobacterium Bovis ◽  
Interferon Gamma ◽  
Whole Blood ◽  
Characteristic Curve ◽  
Antigen Recognition ◽  
Syncerus Caffer ◽  
Content Type ◽  
Domestic Species ◽  
Wide Range ◽  
Ifn Γ

ABSTRACTAfrican buffaloes (Syncerus caffer) are maintenance hosts ofMycobacterium bovis, the causative agent of bovine tuberculosis. They act as reservoirs of this infection for a wide range of wildlife and domestic species, and the detection of infected animals is important to control the geographic spread and transmission of the disease. Interferon gamma (IFN-γ) release assays (IGRAs) utilizing pathogen-derived peptide antigens are highly specific tests ofM. bovisinfection; however, the diagnostic sensitivities of these assays are suboptimal. We evaluated the diagnostic utility of measuring antigen-dependent interferon gamma-induced protein 10 (IP-10) release as an alternative to measuring IFN-γ levels.M. bovis-exposed buffaloes were tested using the Bovigam PC-EC and Bovigam PC-HP assays and a modified QuantiFERON TB-Gold (mQFT) assay. IP-10 was measured in the harvested plasma and was produced in significantly greater abundance in response toM. bovisantigens in Bovigam-positive than in Bovigam-negative animals. For each assay, using the Bovigam results as a reference, receiver operating characteristic curve analysis was done to determine diagnostically relevant cutoff values for IP-10. Thereafter, mQFT test results derived from measurement of IP-10 and IFN-γ were compared and a larger number of Bovigam-positive animals were detected using IP-10 as a diagnostic marker. Moreover, using IP-10, agreement between the mQFT assay and the Bovigam assays was increased, while the excellent agreement between the Bovigam assays was retained. We conclude that IP-10 is a sensitive marker of antigen recognition and that measurement of this cytokine in antigen-stimulated whole blood might increase the sensitivity of conventional IGRAs in African buffaloes.

The Luc2 gene enhances reliability of bicistronic assays

2013 ◽  
Vol 8 (5) ◽  
pp. 423-431 ◽  
Author(s):  
Tomáš Mašek ◽  
Václav Vopalenský ◽  
Martin Pospíšek
Keyword(s):  
Flow Cytometric Analysis ◽  
Firefly Luciferase ◽  
Luciferase Reporter ◽  
Luciferase Gene ◽  
Coding Region ◽  
Entry Site ◽  
Internal Ribosome Entry ◽  
Reverse Transcription Pcr ◽  
Firefly Luciferase Gene ◽  
Cryptic Transcription

AbstractLuciferases are prominent reporters in molecular and cellular biology investigations including miRNA target studies and the determination of Internal Ribosome Entry Site (IRES) activities in bicistronic assays. A majority of the current bicistronic vectors contain a firefly luciferase reporter as the second cistron. One reason for this is the presence of cryptic transcription start sites inside the luciferase gene. We present here an experimental evaluation of the cryptic transcription within the latest version of the firefly luciferase gene, luc2. Using flow cytometric analysis, we observed a negligible amount of cryptic transcriptional activity that was only slightly above the background of untransfected cells. Nevertheless, quantitative reverse transcription PCR experiments revealed a six-to-nine-fold gradual increase of transcription along the coding region of the gene. The level of cryptic transcription from the coding region of the improved luc2 firefly luciferase gene is significantly lower when compared to the luc+ gene. In summary, the luc2 better fulfills the requirements of bicistronic assays than the previous luc+ version. The observed low cryptic transcription activity in luc2 could be limiting only in cases where weak IRESs are studied.

scholarly journals APP1 Transcription Is Regulated by Inositol-phosphorylceramide Synthase 1-Diacylglycerol Pathway and Is Controlled by ATF2 Transcription Factor in Cryptococcus neoformans

2005 ◽  
Vol 280 (43) ◽  
pp. 36055-36064 ◽  
Author(s):  
Lydia Mare ◽  
Roberta Iatta ◽  
Maria Teresa Montagna ◽  
Chiara Luberto ◽  
Maurizio Del Poeta
Keyword(s):  
Transcription Factor ◽  
Cryptococcus Neoformans ◽  
Firefly Luciferase ◽  
Negative Regulator ◽  
Bioactive Molecules ◽  
Luciferase Reporter ◽  
Wild Type ◽  
Consensus Sequences ◽  
Firefly Luciferase Gene

Inositol-phosphorylceramide synthase 1 (Ipc1) is a fungal-specific enzyme that regulates the level of two bioactive molecules, phytoceramide and diacylglycerol (DAG). In previous studies, we demonstrated that Ipc1 regulates the expression of the antiphagocytic protein 1 (App1), a novel fungal factor involved in pathogenicity of Cryptococcus neoformans. Here, we investigated the molecular mechanism by which Ipc1 regulates App1. To this end, the APP1 promoter was fused to the firefly luciferase gene in the C. neofor-mans GAL7:IPC1 strain, in which the Ipc1 expression can be modulated, and found that the luciferase activity was indeed regulated when Ipc1 was modulated. Next, using the luciferase reporter assay in both C. neoformans wild-type and GAL7:IPC1 strains, we investigated the role of DAG and sphingolipids in the activation of the APP1 promoter and found that treatment with 1,2-dioctanoylglycerol does increase APP1 transcription, whereas treatment with phytosphingosine or ceramides does not. Two putative consensus sequences were found in the APP1 promoter for ATF and AP-2 transcription factors. Mutagenesis analysis of these sequences revealed that they play a key role in the regulation of APP1 transcription: ATF is an activator, whereas AP-2 in a negative regulator. Finally, we identified a putative Atf2 transcription factor, which is required for APP1 transcription and under the control of Ipc1-DAG pathway. These studies provide novel regulatory mechanisms of the sphingolipid pathway involved in the regulation of gene transcription of C. neoformans.

scholarly journals Reporter gene technology to assess activity of antimycobacterial agents in macrophages.

1996 ◽  
Vol 40 (6) ◽  
pp. 1542-1544 ◽  
Author(s):  
T M Arain ◽  
A E Resconi ◽  
D C Singh ◽  
C K Stover
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Reporter Gene ◽  
Mycobacterium Bovis ◽  
Firefly Luciferase ◽  
Gene Technology ◽  
Human Macrophages ◽  
Mycobacterium Bovis Bcg ◽  
Antimycobacterial Agents ◽  
Reporter Strains ◽  
Intensive Procedures

Reporter strains of Mycobacterium tuberculosis and Mycobacterium bovis BCG endogenously expressing firefly luciferase were used in bioluminescence assays to evaluate the activities of isoniazid and rifampin against mycobacteria sequestered in human macrophages. This methodology allowed the efficacy of antibiotics against intracellular mycobacteria to be assessed without the labor-intensive procedures and protracted incubation requirements associated with conventional CFU determinations.

scholarly journals Transfer of Plasmid DNA to Clinical Coagulase-Negative Staphylococcal Pathogens by Using a Unique Bacteriophage

2015 ◽  
Vol 81 (7) ◽  
pp. 2481-2488 ◽  
Author(s):  
Volker Winstel ◽  
Petra Kühner ◽  
Bernhard Krismer ◽  
Andreas Peschel ◽  
Holger Rohde
Keyword(s):  
Plasmid Dna ◽  
Genetic Manipulation ◽  
Current Knowledge ◽  
Virulence Determinants ◽  
Coagulase Negative Staphylococci ◽  
Reliable Technique ◽  
Content Type ◽  
Research Activities ◽  
Wide Range ◽  
Genetic Barriers

ABSTRACTGenetic manipulation of emerging bacterial pathogens, such as coagulase-negative staphylococci (CoNS), is a major hurdle in clinical and basic microbiological research. Strong genetic barriers, such as restriction modification systems or clustered regularly interspaced short palindromic repeats (CRISPR), usually interfere with available techniques for DNA transformation and therefore complicate manipulation of CoNS or render it impossible. Thus, current knowledge of pathogenicity and virulence determinants of CoNS is very limited. Here, a rapid, efficient, and highly reliable technique is presented to transfer plasmid DNA essential for genetic engineering to important CoNS pathogens from a uniqueStaphylococcus aureusstrain via a specificS. aureusbacteriophage, Φ187. Even strains refractory to electroporation can be transduced by this technique once donor and recipient strains share similar Φ187 receptor properties. As a proof of principle, this technique was used to delete the alternative transcription factor sigma B (SigB) via allelic replacement in nasal and clinicalStaphylococcus epidermidisisolates at high efficiencies. The described approach will allow the genetic manipulation of a wide range of CoNS pathogens and might inspire research activities to manipulate other important pathogens in a similar fashion.

scholarly journals Use of Proteins Identified through a Functional Genomic Screen To Develop a Protein Subunit Vaccine That Provides Significant Protection against Virulent Streptococcus suis in Pigs

2017 ◽  
Vol 86 (3) ◽  
Author(s):  
Susan L. Brockmeier ◽  
Crystal L. Loving ◽  
Tracy L. Nicholson ◽  
Jinhong Wang ◽  
Sarah E. Peters ◽  
...  
Keyword(s):  
Immune Response ◽  
Vaccine Trial ◽  
Streptococcus Suis ◽  
Protein Subunit ◽  
Content Type ◽  
Degree Of Protection ◽  
Wide Range ◽  
Associated Proteins ◽  
Clinical Protection ◽  
Cellular Immune

ABSTRACT Streptococcus suis is a bacterium that is commonly carried in the respiratory tract and that is also one of the most important invasive pathogens of swine, commonly causing meningitis, arthritis, and septicemia. Due to the existence of many serotypes and a wide range of immune evasion capabilities, efficacious vaccines are not readily available. The selection of S. suis protein candidates for inclusion in a vaccine was accomplished by identifying fitness genes through a functional genomics screen and selecting conserved predicted surface-associated proteins. Five candidate proteins were selected for evaluation in a vaccine trial and administered both intranasally and intramuscularly with one of two different adjuvant formulations. Clinical protection was evaluated by subsequent intranasal challenge with virulent S. suis . While subunit vaccination with the S. suis proteins induced IgG antibodies to each individual protein and a cellular immune response to the pool of proteins and provided substantial protection from challenge with virulent S. suis , the immune response elicited and the degree of protection were dependent on the parenteral adjuvant given. Subunit vaccination induced IgG reactive against different S. suis serotypes, indicating a potential for cross protection.

Sign in / Sign up

Export Citation Format

Share Document