The Experts below are selected from a list of 6105 Experts worldwide ranked by ideXlab platform
Brenda D Spangler - One of the best experts on this subject based on the ideXlab platform.
-
structure and function of cholera toxin and the related escherichia coli heat labile Enterotoxin
Microbiological Research, 1992Co-Authors: Brenda D SpanglerAbstract:Cholera and the related Escherichia coli-associated diarrheal disease are important problems confronting Third World nations and any area where water supplies can become contaminated. The disease is extremely debilitating and may be fatal in the absence of treatment. Symptoms are caused by the action of cholera toxin, secreted by the bacterium Vibrio cholerae, or by a closely related Heat-Labile Enterotoxin, produced by Escherichia coli, that causes a milder, more common traveler9s diarrhea. Both toxins bind receptors in intestinal epithelial cells and insert an enzymatic subunit that modifies a G protein associated with the adenylate cyclase complex. The consequent stimulated production of cyclic AMP, or other factors such as increased synthesis of prostaglandins by intoxicated cells, initiates a metabolic cascade that results in the excessive secretion of fluid and electrolytes characteristic of the disease. The toxins have a very high degree of structural and functional homology and may be evolutionarily related. Several effective new vaccine formulations have been developed and tested, and a growing family of endogenous cofactors is being discovered in eukaryotic cells. The recent elucidation of the three-dimensional structure of the Heat-Labile Enterotoxin has provided an opportunity to examine and compare the correlations between structure and function of the two toxins. This information may improve our understanding of the disease process itself, as well as illuminate the role of the toxin in studies of signal transduction and G-protein function. Images
-
Structure and function of cholera toxin and the related Escherichia coli Heat-Labile Enterotoxin.
Microbiological Reviews, 1992Co-Authors: Brenda D SpanglerAbstract:Cholera and the related Escherichia coli-associated diarrheal disease are important problems confronting Third World nations and any area where water supplies can become contaminated. The disease is extremely debilitating and may be fatal in the absence of treatment. Symptoms are caused by the action of cholera toxin, secreted by the bacterium Vibrio cholerae, or by a closely related Heat-Labile Enterotoxin, produced by Escherichia coli, that causes a milder, more common traveler9s diarrhea. Both toxins bind receptors in intestinal epithelial cells and insert an enzymatic subunit that modifies a G protein associated with the adenylate cyclase complex. The consequent stimulated production of cyclic AMP, or other factors such as increased synthesis of prostaglandins by intoxicated cells, initiates a metabolic cascade that results in the excessive secretion of fluid and electrolytes characteristic of the disease. The toxins have a very high degree of structural and functional homology and may be evolutionarily related. Several effective new vaccine formulations have been developed and tested, and a growing family of endogenous cofactors is being discovered in eukaryotic cells. The recent elucidation of the three-dimensional structure of the Heat-Labile Enterotoxin has provided an opportunity to examine and compare the correlations between structure and function of the two toxins. This information may improve our understanding of the disease process itself, as well as illuminate the role of the toxin in studies of signal transduction and G-protein function. Images
Moon-sik Yang - One of the best experts on this subject based on the ideXlab platform.
-
Expression of Escherichia coli Heat-Labile Enterotoxin B subunit in transgenic tomato (Solanum lycopersicum L.) fruit
Czech Journal of Genetics and Plant Breeding, 2018Co-Authors: Nguyen Hoang Loc, Dang Thanh Long, Tae-geum Kim, Moon-sik YangAbstract:Loc N.H., Long D.T., Kim T.-G., Yang M.-S. (2014): Expression of Escherichia coli Heat-Labile Enterotoxin B subunit in transgenic tomato (Solanum lycopersicum L.) fruit. Czech J. Genet. Plant Breed., 50: 26–31. We report a feasibility study for expressing the LTB protein ( Escherichia coli Heat-Labile Enterotoxin B subunit) via Agrobacterium -mediated transformation of tomato ( Solanum lycopersicum L.). We produced five regenerated plants obtained on the selection medium supplemented with an antibiotic. Stable integrations of the LTB gene into the genome of these plants were confirmed by Southern blot hybridization. Western blot analysis showed that only two of the five T 0 transgenic tomato plants expressed the pentameric LTB protein in the fruits. An enzyme-linked immunosorbent assay indicated that these two plants synthesized the LTB protein bound specifi cally to GM1 ganglioside, suggesting that the LTB subunits formed active pentamers. The LTB protein produced in tomatoes can be a potential candidate for inexpensive, safe, and effective plant-based vaccines.
-
Expression of the Escherichia coli Heat-Labile Enterotoxin B subunit in transgenic watercress (Nasturtium officinale L.)
Plant Cell Tissue and Organ Culture (PCTOC), 2011Co-Authors: Nguyen Song, Nguyen Quang Duc Tien, Tang Thuy Minh, Moon-sik YangAbstract:A gene encoding the B subunit of the enterotoxigenic Escherichia coli Heat-Labile Enterotoxin (LTB) was adapted to the optimized plant coding sequence, and fused to the endoplasmic reticulum retention signal SEKDEL in order to enhance its expression level and protein assembly in plants. The synthetic LTB (sLTB) gene was placed into a plant expression vector under the control of the CaMV 35S promoter, and subsequently introduced into the watercress ( Nasturtium officinale L . ) plant by the Agrobacterium -mediated transformation method. The integration of the sLTB gene into the genomic DNA of transgenic plants was confirmed by genomic DNA PCR amplification. The assembly of plant-produced LTB protein was detected by western blot analysis. The highest amount of LTB protein produced in transgenic watercress leaf tissue was approximately 1.3% of the total soluble plant protein. G_M1-ganglioside enzyme-linked immunosorbent assay indicated that plant-synthesized LTB protein bound specifically to G_M1-ganglioside, which is the receptor for biologically active LTB on the cell surface, suggesting that the plant-synthesized LTB subunits formed biologically active pentamers.
-
tissue culture and expression of escherichia coli heat labile Enterotoxin b subunit in transgenic peperomia pellucida
Protein Expression and Purification, 2010Co-Authors: Nguyen Hoang Bach, Moon-sik YangAbstract:The B subunit of Escherichia coli Heat-Labile Enterotoxin (LTB), a non-toxic molecule with potent biological properties, is a powerful mucosal and parenteral adjuvant that induces a strong immune response against co-administered or coupled antigens. We synthesized a gene encoding the LTB adapted to the optimized coding sequences in plants and fused to the endoplasmic reticulum retention signal SEKDEL to enhance its expression level and protein assembly in plants. The synthetic LTB gene was located into a plant expression vector under the control of CaMV 35S promoter and was introduced into Peperomia pellucida by biolistic transformation method. The integration of synthetic LTB gene into genomic DNA of transgenic plants was confirmed by genomic DNA PCR amplification method. The assembly of plant-produced LTB was detected by western blot analysis. The amount of LTB protein produced in transgenic P. pellucida leaves was approximately 0.75% of the total soluble plant protein. Enzyme-linked immunosorbent assay indicated that plant-synthesized LTB protein bound specifically to GM1-ganglioside, which is receptor for LTB on the cell surface, suggesting that the LTB subunits formed biological active pentamers.
-
synthesis and assembly of escherichia coli heat labile Enterotoxin b subunit in transgenic lettuce lactuca sativa
Protein Expression and Purification, 2007Co-Authors: Taejin Kang, Yong Suk Jang, Charles J Arntzen, Moon-sik YangAbstract:Abstract Escherichia coli Heat-Labile Enterotoxin B subunit (LTB) strongly induces immune responses and can be used as an adjuvant for co-administered antigens. Synthetic LTB (sLTB) based on optimal codon usage by plants was introduced into lettuce cells (Lactuca sativa) by Agrobacterium tumefaciens-mediated transformation methods. The sLTB gene was detected in the genomic DNA of transgenic lettuce leaf cells by PCR DNA amplification. Synthesis and assembly of the sLTB protein into oligomeric structures of pentameric size was observed in transgenic plant extracts using Western blot analysis. The binding of sLTB pentamers to intestinal epithelial cell membrane glycolipid receptors was confirmed by GM1-ganglioside enzyme-linked immunosorbent assay (GM1-ELISA). Based on the results of ELISA, sLTB protein comprised approximately 1.0–2.0% of total soluble protein in transgenic lettuce leaf tissues. The synthesis and assembly of sLTB monomers into biologically active oligomers in transgenic lettuce leaf tissues demonstrates the feasibility of the use of edible plant-based vaccines consumed in the form of raw plant materials to induce mucosal immunity.
-
Expression of the B Subunit of E. coli Heat-Labile Enterotoxin in the Chloroplasts of Plants and its Characterization
Transgenic Research, 2003Co-Authors: Taejin Kang, Yong Suk Jang, Mi-ok Jang, Moon-sik YangAbstract:Transgenic chloroplasts have become attractive systems for heterologous gene expressions because of unique advantages. Here, we report a feasibility study for producing the nontoxic B subunit of Escherichia coli Heat-Labile Enterotoxin (LTB) via chloroplast transformation of tobacco. Stable site-specific integration of the LTB gene into chloroplast genome was confirmed by PCR and genomic Southern blot analysis in transformed plants. Immunoblot analysis indicated that plant-derived LTB protein was oligomeric, and dissociated after boiling. Pentameric LTB molecules were the dominant molecular species in LTB isolated from transgenic tobacco leaf tissues. The amount of LTB protein detected in transplastomic tobacco leaf was approximately 2.5% of the total soluble plant protein, approximately 250-fold higher than in plants generated via nuclear transformation. The GM1–ELISA binding assay indicated that chloroplast-synthesized LTB protein bound to GM1-ganglioside receptors. LTB protein with biochemical properties identical to native LTB protein in the chloroplast of edible plants opens the way for inexpensive, safe, and effective plant-based edible vaccines for humans and animals.
Charalambos D Partidos - One of the best experts on this subject based on the ideXlab platform.
-
transcutaneous immunization with tetanus toxoid and mutants of escherichia coli heat labile Enterotoxin as adjuvants elicits strong protective antibody responses
The Journal of Infectious Diseases, 2003Co-Authors: Rob Tierney, Rino Rappuoli, Annesophie Beignon, Sylviane Muller, Dorothea Sesardic, Charalambos D PartidosAbstract:In this study, the adjuvanticity of 2 nontoxic derivatives (LTK63 and LTR72) of Heat-Labile Enterotoxin of Escherichia coli (LT) was evaluated and was compared with that of a cytosine phosphodiester-guanine (CpG) motif, after transcutaneous immunization with tetanus toxoid (TT). TT plus LTR72 elicited the strongest antibody responses, compared with those elicited by the other vaccines (TT, TT plus LTK63, TT plus CpG, and TT plus LTK63 plus CpG); it neutralized the toxin and conferred full protection after passive transfer in mice. Preexisting immunity to LT mutants did not adversely affect their adjuvant potency. Both LTK63 and LTR72 promoted the induction of IgG1 antibodies. In contrast, mice receiving either CpG motif alone or CpG motif plus LTK63 produced strong IgG2a anti-TT antibody responses. Overall, these findings demonstrate that mutants of Enterotoxins with reduced toxicity are effective adjuvants for transcutaneous immunization.
Timothy J Oleary - One of the best experts on this subject based on the ideXlab platform.
-
the liposome pcr assay is more sensitive than the vibrio cholerae Enterotoxin and escherichia coli heat labile Enterotoxin reversed passive latex agglutination test at detecting cholera toxin in feces and water
Journal of Clinical Microbiology, 2010Co-Authors: David L Evers, Junkun He, Jeffrey T Mason, Timothy J OlearyAbstract:Practical detection of cholera toxin (CT) by a liposome PCR (LPCR) immunoassay was compared to that of an established V. cholerae Enterotoxin and Escherichia coli Heat-Labile Enterotoxin reversed passive latex agglutination (VET-RPLA) assay. LPCR detected CT in the range of 10 pg/ml to 100 ng/ml in simulated feces and environmental water. Detection by VET-RPLA required at least 4 to 19 ng/ml CT.
Rino Rappuoli - One of the best experts on this subject based on the ideXlab platform.
-
transcutaneous immunization with tetanus toxoid and mutants of escherichia coli heat labile Enterotoxin as adjuvants elicits strong protective antibody responses
The Journal of Infectious Diseases, 2003Co-Authors: Rob Tierney, Rino Rappuoli, Annesophie Beignon, Sylviane Muller, Dorothea Sesardic, Charalambos D PartidosAbstract:In this study, the adjuvanticity of 2 nontoxic derivatives (LTK63 and LTR72) of Heat-Labile Enterotoxin of Escherichia coli (LT) was evaluated and was compared with that of a cytosine phosphodiester-guanine (CpG) motif, after transcutaneous immunization with tetanus toxoid (TT). TT plus LTR72 elicited the strongest antibody responses, compared with those elicited by the other vaccines (TT, TT plus LTK63, TT plus CpG, and TT plus LTK63 plus CpG); it neutralized the toxin and conferred full protection after passive transfer in mice. Preexisting immunity to LT mutants did not adversely affect their adjuvant potency. Both LTK63 and LTR72 promoted the induction of IgG1 antibodies. In contrast, mice receiving either CpG motif alone or CpG motif plus LTK63 produced strong IgG2a anti-TT antibody responses. Overall, these findings demonstrate that mutants of Enterotoxins with reduced toxicity are effective adjuvants for transcutaneous immunization.
-
Mutants of the Escherichia coli Heat-Labile Enterotoxin as safe and strong adjuvants for intranasal delivery of vaccines.
Expert Review of Vaccines, 2003Co-Authors: Samuele Peppoloni, Mariagrazia Pizza, Rino Rappuoli, Paolo Ruggiero, Mario Contorni, Maurizio Morandi, Audino Podda, Giuseppe Del GiudiceAbstract:Cholera toxin and Escherichia coli Heat-Labile Enterotoxin are powerful mucosal adjuvants but their high toxicity hampers their use in humans. Site-directed mutagenesis has allowed the generation of several cholera toxin and E. coli Heat-Labile Enterotoxin mutants with abolished or strongly reduced toxicity that still retain strong mucosal adjuvanticity. Among them, LTK63 (Ser to Lys substitution at position 63 in the A subunit) is completely nontoxic and LTR72 (Ala to Arg at position 72) retains a very low residual enzymatic activity. Both of them have been shown to be safe and effective in enhancing the immunogenicity of intranasally coadministered vaccines, also resulting in protective responses in several animal models. Clinical grade preparations of these mutants have now been produced, tested in animals and proven to be totally safe. Indeed, they did not induce any inflammatory event in the respiratory tract nor, more importantly, in the olfactory bulbs and in the meninges. The fully nontoxic LTK63 mutant has now been successfully tested in human volunteers with a trivalent subunit influenza vaccine.
-
Mutation of a buried residue causes loss of activity but no conformational change in the Heat-Labile Enterotoxin of Escherichia coli.
Nature Structural & Molecular Biology, 1995Co-Authors: Ethan A. Merritt, Steve Sarfaty, Mariagrazia Pizza, Mario Domenighini, Rino Rappuoli, Wim G. J. HolAbstract:The structure of an inactive mutant, Heat-Labile Enterotoxin raises the possibility of a direct functional role for an internal, water-filled cavity.