Reuveny S

General

Full name : Reuveny Shaul

First name : Shaul

Mail : Dept. of Biotechnology, Israel Inst. for BioI. Res., P.O.B. 19, 70450 Ness-Ziona

Zip Code :

City :

Country : Israel

Email :

Phone : (972) 8 381582

Fax : (972) 8 401094

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References (15)

Title : Progress and novel strategies in vaccine development and treatment of anthrax - Chitlaru_2011_Immunol.Rev_239_221
Author(s) : Chitlaru T , Altboum Z , Reuveny S , Shafferman A
Ref : Immunol Rev , 239 :221 , 2011
Abstract : The lethal anthrax disease is caused by spores of the gram-positive Bacillus anthracis, a member of the cereus group of bacilli. Although the disease is very rare in the Western world, development of anthrax countermeasures gains increasing attention due to the potential use of B. anthracis spores as a bio-terror weapon. Protective antigen (PA), the non-toxic subunit of the bacterial secreted exotoxin, fulfills the role of recognizing a specific receptor and mediating the entry of the toxin into the host target cells. PA elicits a protective immune response and represents the basis for all current anthrax vaccines. Anti-PA neutralizing antibodies are useful correlates for protection and for vaccine efficacy evaluation. Post exposure anti-toxemic and anti-bacteremic prophylactic treatment of anthrax requires prolonged antibiotic administration. Shorter efficient postexposure treatments may require active or passive immunization, in addition to antibiotics. Although anthrax is acknowledged as a toxinogenic disease, additional factors, other than the bacterial toxin, may be involved in the virulence of B. anthracis and may be needed for the long-lasting protection conferred by PA immunization. The search for such novel factors is the focus of several high throughput genomic and proteomic studies that are already leading to identification of novel targets for therapeutics, for vaccine candidates, as well as biomarkers for detection and diagnosis.
ESTHER : Chitlaru_2011_Immunol.Rev_239_221
PubMedSearch : Chitlaru_2011_Immunol.Rev_239_221
PubMedID: 21198675

Title : Efficacy of a potential trivalent vaccine based on Hc fragments of botulinum toxins A, B, and E produced in a cell-free expression system - Zichel_2010_Clin.Vaccine.Immunol_17_784
Author(s) : Zichel R , Mimran A , Keren A , Barnea A , Steinberger-Levy I , Marcus D , Turgeman A , Reuveny S
Ref : Clin Vaccine Immunol , 17 :784 , 2010
Abstract : Botulinum toxins produced by the anaerobic bacterium Clostridium botulinum are the most potent biological toxins in nature. Traditionally, people at risk are immunized with a formaldehyde-inactivated toxin complex. Second generation vaccines are based on the recombinant carboxy-terminal heavy-chain (Hc) fragment of the neurotoxin. However, the materialization of this approach is challenging, mainly due to the high AT content of clostridial genes. Herein, we present an alternative strategy in which the native genes encoding Hc proteins of botulinum toxins A, B, and E were used to express the recombinant Hc fragments in a cell-free expression system. We used the unique property of this open system to introduce different combinations of chaperone systems, protein disulfide isomerase (PDI), and reducing/oxidizing environments directly to the expression reaction. Optimized expression conditions led to increased production of soluble Hc protein, which was successfully scaled up using a continuous exchange (CE) cell-free system. Hc proteins were produced at a concentration of more than 1 mg/ml and purified by one-step Ni(+) affinity chromatography. Mice immunized with three injections containing 5 microg of any of the in vitro-expressed, alum-absorbed, Hc vaccines generated a serum enzyme-linked immunosorbent assay (ELISA) titer of 10(5) against the native toxin complex, which enabled protection against a high-dose toxin challenge (10(3) to 10(6) mouse 50% lethal dose [MsLD(50)]). Finally, immunization with a trivalent HcA, HcB, and HcE vaccine protected mice against the corresponding trivalent 10(5) MsLD(50) toxin challenge. Our results together with the latest developments in scalability of the in vitro protein expression systems offer alternative routes for the preparation of botulinum vaccine.
ESTHER : Zichel_2010_Clin.Vaccine.Immunol_17_784
PubMedSearch : Zichel_2010_Clin.Vaccine.Immunol_17_784
PubMedID: 20357058

Title : Effective post-exposure protection against lethal orthopoxviruses infection by vaccinia immune globulin involves induction of adaptive immune response - Lustig_2009_Vaccine_27_1691
Author(s) : Lustig S , Maik-Rachline G , Paran N , Melamed S , Israely T , Erez N , Orr N , Reuveny S , Ordentlich A , Laub O , Shafferman A , Velan B
Ref : Vaccine , 27 :1691 , 2009
Abstract : The therapeutic potential of human vaccinia immunoglobulin (VIG) in orthopoxvirus infection was examined using two mouse models for human poxvirus, based on Ectromelia virus and Vaccinia Western Reserve (WR) respiratory infections. Despite the relatively fast clearance of human VIG from mice circulation, a single VIG injection protected immune-competent mice against both infections. Full protection against lethal Ectromelia virus infection was achieved by VIG injection up to one day post-exposure, and even injection of VIG two or three days post-infection conferred solid protection (60-80%). Nevertheless, VIG failed to protect VACV-WR challenged immune-deficient mice, even though repeated injections prolonged SCID mice survival. These results suggest the involvement of host immunity in protection. VIG provides the initial protective time-window allowing induction of the adaptive response required to achieve complete protection. Additionally, VIG can be administered in conjunction with active Vaccinia-Lister vaccination. Vaccine efficiency is not impaired, providing a non-prohibitive VIG dose is used. Thus, VIG can be used as a prophylactic measure against post-vaccinal complications but could also serve for post-exposure treatment against smallpox.
ESTHER : Lustig_2009_Vaccine_27_1691
PubMedSearch : Lustig_2009_Vaccine_27_1691
PubMedID: 19195492

Title : Isolation and chimerization of a highly neutralizing antibody conferring passive protection against lethal Bacillus anthracis infection - Rosenfeld_2009_PLoS.One_4_e6351
Author(s) : Rosenfeld R , Marcus H , Ben-Arie E , Lachmi BE , Mechaly A , Reuveny S , Gat O , Mazor O , Ordentlich A
Ref : PLoS ONE , 4 :e6351 , 2009
Abstract : Several studies have demonstrated that the passive transfer of protective antigen (PA)-neutralizing antibodies can protect animals against Bacillus anthracis infection. The standard protocol for the isolation of PA-neutralizing monoclonal antibodies is based upon a primary selection of the highest PA-binders by ELISA, and usually yields only few candidates antibodies. We demonstrated that by applying a PA-neutralization functionality-based screen as the primary criterion for positive clones, it was possible to isolate more than 100 PA-neutralizing antibodies, some of which exhibited no measurable anti-PA titers in ELISA. Among the large panel of neutralizing antibodies identified, mAb 29 demonstrated the most potent activity, and was therefore chimerized. The variable region genes of the mAb 29 were fused to human constant region genes, to form the chimeric 29 antibody (cAb 29). Guinea pigs were fully protected against infection by 40LD(50)B. anthracis spores following two separate administrations with 10 mg/kg of cAb 29: the first administration was given before the challenge, and a second dose was administered on day 4 following exposure. Moreover, animals that survived the challenge and developed endogenous PA-neutralizing antibodies with neutralizing titers above 100 were fully protected against repeat challenges with 40LD(50) of B. anthracis spores. The data presented here emphasize the importance of toxin neutralization-based screens for the efficient isolation of protective antibodies that were probably overlooked in the standard screening protocol. The protective activity of the chimeric cAb 29 demonstrated in this study suggest that it may serve as an effective immunotherapeutic agent against anthrax.
ESTHER : Rosenfeld_2009_PLoS.One_4_e6351
PubMedSearch : Rosenfeld_2009_PLoS.One_4_e6351
PubMedID: 19629185

Title : Effects of spontaneous deamidation on the cytotoxic activity of the Bacillus anthracis protective antigen - Zomber_2005_J.Biol.Chem_280_39897
Author(s) : Zomber G , Reuveny S , Garti N , Shafferman A , Elhanany E
Ref : Journal of Biological Chemistry , 280 :39897 , 2005
Abstract : Protective antigen (PA) is a central virulence factor of Bacillus anthracis and a key component in anthrax vaccines. PA binds to target cell receptors, is cleaved by the furin protease, self-aggregates to heptamers, and finally internalizes as a complex with either lethal or edema factors. Under mild room temperature storage conditions, PA cytotoxicity decreased (t(1/2) approximately 7 days) concomitant with the generation of new acidic isoforms, probably through deamidation of Asn residues. Ranking all 68 Asn residues in PA based on their predicted deamidation rates revealed five residues with half-lives of <60 days, and these residues were further analyzed: Asn10 in the 20-kDa region, Asn162 at P6 vicinal to the furin cleavage site, Asn306 in the pro-pore translocation loop, and both Asn713 and Asn719 in the receptor-binding domain. We found that PA underwent spontaneous deamidation at Asn162 upon storage concomitant with decreased susceptibility to furin. A panel of model synthetic furin substrates was used to demonstrate that Asn162 deamidation led to a 20-fold decrease in the bimolecular rate constant (k(cat)/Km) of proteolysis due to the new negatively charged residue at P6 in the furin recognition sequence. Furthermore, reduced PA cytotoxicity correlated with a decrease in PA cell binding and also with deamidation of Asn713 and Asn719. On the other hand, neither deamidation of Asn10 or Asn306 nor impairment of heptamerization could be observed upon prolonged PA storage. We suggest that PA inactivation during storage is associated with susceptible deamidation sites, which are intimately involved in both mechanisms of PA cleavage by furin and PA-receptor binding.
ESTHER : Zomber_2005_J.Biol.Chem_280_39897
PubMedSearch : Zomber_2005_J.Biol.Chem_280_39897
PubMedID: 16188881

Title : Molecular Aspects of Catalysis and of Allosteric Regulation of Aceytlcholinesterases -
Author(s) : Shafferman A , Ordentlich A , Barak D , Kronman C , Ariel N , Leitner M , Segall Y , Bromberg A , Reuveny S , Marcus D , Bino T , Lazar A , Cohen S , Velan B
Ref : In Enzyme of the Cholinesterase Family - Proceedings of Fifth International Meeting on Cholinesterases , (Quinn, D.M., Balasubramanian, A.S., Doctor, B.P., Taylor, P., Eds) Plenum Publishing Corp. :189 , 1995
PubMedID:

Title : Denaturation of Recombinant Human Acetylcholinesterase -
Author(s) : Lebleu M , Clery C , Masson P , Reuveny S , Marcus D , Velan B , Shafferman A
Ref : In Enzyme of the Cholinesterase Family - Proceedings of Fifth International Meeting on Cholinesterases , (Quinn, D.M., Balasubramanian, A.S., Doctor, B.P., Taylor, P., Eds) Plenum Publishing Corp. :131 , 1995
PubMedID:

Title : Involvement of oligomerization, N-glycosylation and sialylation in the clearance of cholinesterases from the circulation - Kronman_1995_Biochem.J_311_959
Author(s) : Kronman C , Velan B , Marcus D , Ordentlich A , Reuveny S , Shafferman A
Ref : Biochemical Journal , 311 :959 , 1995
Abstract : The possible role of post-translational modifications such as subunit oligomerization, protein glycosylation and oligosaccharide processing on the circulatory life-time of proteins was studied using recombinant human acetylcholinesterase (rHuAChE). Different preparations of rHuAChE containing various amounts of tetramers, dimers and monomers are cleared at similar rates from the circulation, suggesting that oligomerization does not play an important role in determining the rate of clearance. An engineered rHuAChE mutant containing only one N-glycosylation site was cleared from the circulation more rapidly than the wild-type triglycosylated enzyme. On the other hand, hyperglycosylated mutants containing either four or five occupied N-glycosylation sites, analagous to those present on the slowly cleared fetal bovine serum acetylcholinesterase (FBS-AChE), were also cleared more rapidly from the bloodstream than the wild-type species. Furthermore, the two different tetraglycosylated mutants were cleared at different rates while the pentaglycosylated mutant exhibited the most rapid clearance profile. These results imply that though the number of N-glycosylation sites plays a role in the circulatory life-time of the enzyme, the number of N-glycan units in itself does not determine the rate of clearance. When saturating amounts of asialofetuin were administered together with rHuAChE, the circulatory half-life of the enzyme was dramatically increased (from 80 min to 19 h) and was found to be similar to that displayed by plasma-derived cholinesterases while desialylation of these enzymes caused a sharp decrease in the circulatory half-life to approximately 3-5 min. Determination of the average number of sialic acid residues per enzyme subunit of the five different N-glycosylation species generated, revealed that the rate of clearance is not a function of the absolute number of appended sialic acid moieties but rather of the number of unoccupied sialic acid attachment sites per enzyme molecule. Specifically, we demonstrate an inverse-linear relationship between the number of vacant sialic acid attachment sites and the values of the enzyme residence time within the bloodstream.
ESTHER : Kronman_1995_Biochem.J_311_959
PubMedSearch : Kronman_1995_Biochem.J_311_959
PubMedID: 7487957

Title : Amino Acids Determining Specificity to OP-Agents and Facilitating the Aging Process in Human Acetylcholinesterase -
Author(s) : Ordentlich A , Kronman C , Stein D , Ariel N , Reuveny S , Marcus D , Segall Y , Barak D , Velan B , Shafferman A
Ref : In Enzyme of the Cholinesterase Family - Proceedings of Fifth International Meeting on Cholinesterases , (Quinn, D.M., Balasubramanian, A.S., Doctor, B.P., Taylor, P., Eds) Plenum Publishing Corp. :221 , 1995
PubMedID:

Title : Evaluation of anchorage-dependent cell propagation systems for production of human acetylcholinesterase by recombinant 293 cells - Lazar_1993_Cytotech_13_115
Author(s) : Lazar A , Reuveny S , Kronman C , Velan B , Shafferman A
Ref : Cytotechnology , 13 :115 , 1993
Abstract : Production of recombinant human acetylcholinesterase (AChE) by a high producer human embryonic kidney cell line (293) was evaluated by three main cell propagation systems; surface propagator, fixed-bed reactor and stirred microcarrier cultures. The recombinant cell line expresses AChE levels as high as 10-20 mg/l/day. System productivities in either the surface propagator (multitray system), or in the fixed-bed reactor (polyurethane macroporous sponges) were 4-8 mg AChE/l/day during a production period of 8 days. Similar productive rates, yet longer production periods (up to 22 days), were obtained in microcarrier (MC) cultures using either polystyrene beads (Biosilon); collagen-coated dextran beads (Cytodex-3); or gelatin macroporous beads (Cultispher-G). Best results were obtained in an aggregate culture using cellulose beads charged with diethylaminoethyl (DEAE) groups, (Servacel), as carriers. In this culture, a system productivity of 6-10 mg/l/day was maintained for 28 days.
ESTHER : Lazar_1993_Cytotech_13_115
PubMedSearch : Lazar_1993_Cytotech_13_115
PubMedID: 7764576

Title : Differentiation of myoblasts and CNS cells grown either separately or as co-cultures on microcarriers - Shahar_1992_Cytotech_9_107
Author(s) : Shahar A , Reuveny S , Zhang M , Espinosa de los Monteros A , de Vellis J , Shainberg A
Ref : Cytotechnology , 9 :107 , 1992
Abstract : Dispersed neuronal and muscular elements from fetal or neonatal origin, can organize and mature in culture when grown on positively charged cylindrical microcarriers (MCS), to a stage which simulate in vivo maturation. Cells arrange themselves on the MCS to form aggregates which remain floating in the nutrient medium. In such a tridimensional organization, the neuronal tissue is capable of regenerating a network of nerve fibers which establish synapse interconnections and undergo myelination. Oligodendrocytes organize on MCS in a tridimensional pattern and produce extensive myelin-like membranes. Myoblasts in MC-cultures fuse into polynucleated myotubes which become striated and contract spontaneously. Creatine kinase and acetylcholine receptor (AChR) are formed during myogenesis in similar quantities in MC-cultures and in monolayers. When both neuronal and muscle tissues are prepared from the same fetus (autologous nerve-muscle co-cultures) and are cultured on MCS, they interconnect to form neuro-muscular junctions. Cells from both tissues, exhibit better differentiation, for longer periods in MC-cultures than they do in monolayers. The floating functional entities are easy to sample and can be harvested for ultrastructural, immunocytochemical and biochemical analysis. In addition, MC-cultures can be used as a good tool for the study of acute and chronic exposures to toxicological agents, as well as for implantation into demyelinated, injured or dystrophic tissues. In this case the MCS in the implanted entities will serve as identifiable markers.
ESTHER : Shahar_1992_Cytotech_9_107
PubMedSearch : Shahar_1992_Cytotech_9_107
PubMedID: 1369162

Title : Equipment and procedures for production of monoclonal antibodies in culture -
Author(s) : Reuveny S , Lazar A
Ref : Adv Biotechnol Processes , 11 :45 , 1989
PubMedID: 2644947

Title : An immobilized hybridoma culture perfusion system for production of monoclonal antibodies - Lazar_1988_Cytotech_1_331
Author(s) : Lazar A , Silberstein L , Mizrahi A , Reuveny S
Ref : Cytotechnology , 1 :331 , 1988
Abstract : A fixed bed perfusion system for hybridoma cell immobilization is presented. The system consists of a culturing vessel (300 ml total volume) in which polyurethane (PU) sponges in the form of small cubes of about 5 mm sides are packed. Cells are immobilized by physical entrapment in the foam matrix. By entrapment of the cells in the pores of the matrix high cell concentration can be maintained in a mechanically protected environment. Medium is continuously circulated by an airlift pump mounted in the cell-free chamber (700 ml total volume).Medium flow rate, feeding rate, dissolved oxygen, pH, nutrient uptake and waste product formation can be easily monitored and controlled. Steady state conditions are established with medium dilution rates of 1.0-1.5 reactor volume per day. The steady state is characterized by a constant cell density, constant culture volume and constant glucose and lactate levels. Cell-free supernatant is collected continuously in a cold room adjacent to the 37 degrees C culture room. Monoclonal antibodies (MAb) are produced at a concentration of 150-200 mug/ml for several weeks. An important feature of the system is the capacity to maintain a population of cells after the growth phase in a non-proliferating state for extended time periods expressing high titers of MAb.
ESTHER : Lazar_1988_Cytotech_1_331
PubMedSearch : Lazar_1988_Cytotech_1_331
PubMedID: 22359168

Title : Differentiation of myoblasts with nerve cells on microcarriers in culture - Shahar_1985_Dev.Biol.Stand_60_263
Author(s) : Shahar A , Mizrahi A , Reuveny S , Zinman T , Shainberg A
Ref : Developmental Biology Stand , 60 :263 , 1985
Abstract : Differentiation of embryonic rat and chick myoblasts was investigated using a tridimensional support made of positively charged, uncoated DEAE-cellulose microcarriers (MC). Following rapid cell attachment, the MC interconnected to form large cell-MC conglomerates which remained floating in the nutrient medium. Cells within the conglomerates fused to form myotubes which synthesized muscle-specific proteins such as: creatine kinase, acetylcholinesterase, acetylcholine receptors, and contracted in response to electrical stimulation. Myotubes, at different stages of differentiation, showed characteristic morphology (as observed by transmission and scanning electron-microscopies). Upon addition of dissociated spinal cord cells to these muscle-MC cultures, intensive sprouting of nerve fibres took place. After a few days an extensive network of nerve fibres was formed on the top of muscle myotubes and nerve-muscle contacts were established.
ESTHER : Shahar_1985_Dev.Biol.Stand_60_263
PubMedSearch : Shahar_1985_Dev.Biol.Stand_60_263
PubMedID: 3899788

Title : Myogenesis on microcarrier cultures - Shainberg_1983_Cell.Biol.Int.Rep_7_727
Author(s) : Shainberg A , Isac A , Reuveny S , Mizrahi A , Shahar A
Ref : Cell Biology International Report , 7 :727 , 1983
Abstract : The capacity of embryonic chick myoblasts to grow in vitro on DEAE-cellulose microcarriers (MC) has been investigated biochemically and morphologically. The cells attached to the MC, replicated and fused to form elongated myotubes. These myotubes synthesized muscle-specific proteins, such as creatine kinase (CK) and acetylcholine receptors (AChR), and they contracted spontaneously. Some of the advantages of this technique are: a) Tridimensional development of myotubes on MC with orientation of fibers parallel to each other; b) Muscle cells can be cultured on MC for long periods (months); c) Easy harvesting of samples at any time during cultivation; d) DEAE-cellulose MC are commercially available, inexpensive and easy to handle.
ESTHER : Shainberg_1983_Cell.Biol.Int.Rep_7_727
PubMedSearch : Shainberg_1983_Cell.Biol.Int.Rep_7_727
PubMedID: 6627408