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1.
J Visc Surg ; 156 Suppl 1: S33-S39, 2019 Sep.
Article in English | MEDLINE | ID: mdl-31303460

ABSTRACT

Malpractice claims are a regularly increasing concern in gastrointestinal surgery. The goal of this study was to compare the current status of claims in two different French-speaking communities by a retrospective descriptive study of surgeons' experiences, from the beginning of their practice up until December 31 2014. Data included the number, the reasons, and the results of medicolegal claims and their jurisdictions. Forty-three surgeons participated in this study. Two hundred medicolegal claims were analyzed. The mean number was 5.8 per surgeon. Bariatric surgery, colorectal surgery and parietal surgery were the most exposed. Forty-six (23%) faults were noted, while no fault was pronounced in 139 (69.5%) cases. The main reasons for lodging complaints were nosocomial infections, anastomotic leaks, poor postoperative care, hollow organ perforation, peripheral neurologic complication, and insufficient preoperative information. Forty-four percent of the complaints were analyzed by the conciliation and compensation commissions and 43.5% by the High Court. In the French-speaking group, there were 13 complaints, two of which gave rise to compensation. French surgeons are highly exposed to complaints: in French law, clumsiness or technical maladdress is considered as a fault. The patient should be informed preoperatively of all possible severe risks of a medical procedure. In Belgium, complications are exceptional and are considered random therapeutic events. Adhering to the recommendations emanating from the French High Authority of Health and Learned Societies as well as accreditation issued by the same High Authority should allow to decrease the number of undesirable events related to care and malpractice.


Subject(s)
Malpractice/legislation & jurisprudence , Surgeons/legislation & jurisprudence , Surgical Procedures, Operative/legislation & jurisprudence , Adult , Aged , Belgium , Compensation and Redress/legislation & jurisprudence , France , Humans , Intraoperative Complications , Malpractice/statistics & numerical data , Middle Aged , Postoperative Complications , Retrospective Studies , Surgeons/statistics & numerical data , Surgical Procedures, Operative/adverse effects , Surgical Procedures, Operative/statistics & numerical data
2.
Acta Chir Belg ; 118(2): 94-98, 2018 Apr.
Article in English | MEDLINE | ID: mdl-28927340

ABSTRACT

OBJECTIVES: Postoperative complications after Laparoscopic sleeve gastrectomy (LSG) can dramatically compromise patient's outcome. The aim of this study is to analyze the per- and postoperative short-term outcomes after LSG and to assess predictive risk factors of complications. METHODS: The study group consisted of 790 patients (610 women and 180 men) who underwent LSG In 2014. All interventions were performed by 18 experienced surgeons members of the Club Coelio. Data about preoperative work-up, surgical techniques, 30-days postoperative morbidity and mortality were collected. Endpoints were perioperative morbidity and mortality and assessment of potential risk factors for complications. RESULTS: Mean age and body mass index were respectively 39 years and 41.5kg/m2. Ninety-one patients (11.5%) had previous bariatric surgery. Morbidity rate was 4.7% (37/790) including 16 leaks (2.0%) and 9 bleedings (1.1%) and no deaths. Risk factors for leak were: previous adjustable banding (p = .0051), with no difference between removal of the banding and LSG in 1 or 2 steps, and type of endostapler (p = .0129). CONCLUSIONS: Leakage after Sleeve was rare but still observed even in experienced hands. The leak rate is particularly high when LSG is performed after adjustable gastric banding removal.


Subject(s)
Gastroplasty/adverse effects , Laparoscopy/adverse effects , Obesity, Morbid/surgery , Postoperative Complications/epidemiology , Adolescent , Adult , Aged , Belgium/epidemiology , Female , Gastroplasty/methods , Humans , Male , Middle Aged , Morbidity/trends , Retrospective Studies , Risk Factors , Survival Rate/trends , Young Adult
3.
Ultrasonics ; 52(8): 971-4, 2012 Dec.
Article in English | MEDLINE | ID: mdl-22939262

ABSTRACT

The goal of this paper is to propose an experimental method allowing the identification of the complete elastic tensor of anisotropic biological materials such as wood using only one sample. To do so, two complementary methods are used. First, the wood eigen-directions are defined from a sample of spherical shape that is then cut into a cube in a way to perform resonant ultrasound spectroscopy (RUS). The method is successfully applied on a reference beech sample with known orthotropic directions. A comparison of the identified elastic constants with those from the literature and some inferred from ultrasonic transmission measurements is given.

4.
J Gen Virol ; 93(Pt 1): 184-193, 2012 Jan.
Article in English | MEDLINE | ID: mdl-21918009

ABSTRACT

Recessive resistance to lettuce mosaic virus (LMV) is conferred in lettuce by the mo1 gene, encoding the eukaryotic translation initiation factor 4E (eIF4E). The C terminus of the viral cylindrical inclusion helicase (CI-Cter), together with the VPg, is involved directly in overcoming mo1 resistance. In this study, recombinant LMV VPg and CI-Cter proteins from wild-type or resistance-breaking isolates were expressed and purified from Escherichia coli. The allelic forms of eIF4E from susceptible or resistant lettuce cultivars were produced similarly and these proteins were used in ELISA-based assays to demonstrate the in vitro binding of the various forms of LMV CI-Cter to both lettuce eIF4E and LMV VPg proteins. All combinations tested displayed significant and specific interactions, and the interaction between the C-terminal part of the LMV CI and eIF4E was confirmed in vivo in bimolecular fluorescence complementation assays. Higher interaction signals for both CI-eIF4E and CI-VPg were observed for LMV-E, indicating that the eIF4E interaction network involving CI and VPg appears to be stronger in the case of this resistance-breaking isolate. This could suggest the need for a minimal interaction threshold for infection success in resistant lettuce, but more precise measurement of the interaction parameters linking eIF4E, VPg and CI is needed in order to reinforce such a hypothesis.


Subject(s)
DNA Helicases/metabolism , Eukaryotic Initiation Factor-4E/metabolism , Lactuca/metabolism , Plant Diseases/virology , Plant Proteins/metabolism , Potyvirus/enzymology , Viral Proteins/metabolism , Amino Acid Motifs , DNA Helicases/chemistry , DNA Helicases/genetics , Eukaryotic Initiation Factor-4E/genetics , Lactuca/genetics , Lactuca/virology , Plant Diseases/genetics , Plant Proteins/genetics , Potyvirus/chemistry , Potyvirus/genetics , Protein Binding , Viral Proteins/chemistry , Viral Proteins/genetics
5.
J Gen Virol ; 88(Pt 3): 1029-1033, 2007 Mar.
Article in English | MEDLINE | ID: mdl-17325377

ABSTRACT

Using recombinant proteins produced in bacteria or in infected plants, interactions between the VPg and HcPro of Lettuce mosaic potyvirus (LMV) and between LMV VPg and the lettuce translation initiation factor 4E, the cap-binding protein (eIF4E), were demonstrated in vitro. Interaction with eIF4E and HcPro both involved the same VPg central domain. The structure of this domain in the VPg context was predicted to include an amphiphilic alpha-helix, with the amino acids related to biological functions in various potyviruses exposed at the hydrophilic side.


Subject(s)
Eukaryotic Initiation Factor-4E/metabolism , Lactuca/metabolism , Potyvirus/physiology , Viral Proteins/metabolism , Plant Proteins/metabolism , Protein Binding , Protein Interaction Mapping , Protein Structure, Secondary , Protein Structure, Tertiary/physiology , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Viral Proteins/genetics
6.
J Biol Chem ; 276(28): 26550-8, 2001 Jul 13.
Article in English | MEDLINE | ID: mdl-11352904

ABSTRACT

The chemokine stromal cell-derived factor 1 (SDF-1) is the natural ligand for CXC chemokine receptor 4 (CXCR4). SDF-1 inhibits infection of CD4+ cells by X4 (CXCR4-dependent) human immunodeficiency virus (HIV) strains. We previously showed that SDF-1 alpha interacts specifically with heparin or heparan sulfates (HSs). Herein, we delimited the boundaries of the HS-binding domain located in the first beta-strand of SDF-1 alpha as the critical residues. We also provide evidence that binding to cell surface heparan sulfate proteoglycans (HSPGs) determines the capacity of SDF-1 alpha to prevent the fusogenic activity of HIV-1 X4 isolates in leukocytes. Indeed, SDF-1 alpha mutants lacking the capacity to interact with HSPGs showed a substantially reduced capacity to prevent cell-to-cell fusion mediated by X4 HIV envelope glycoproteins. Moreover, the enzymatic removal of cell surface HS diminishes the HIV-inhibitory capacity of the chemokine to the levels shown by the HS-binding-disabled mutant counterparts. The mechanisms underlying the optimal HIV-inhibitory activity of SDF-1 alpha when attached to HSPGs were investigated. Combining fluorescence resonance energy transfer and laser confocal microscopy, we demonstrate the concomitant binding of SDF-1 alpha to CXCR4 and HSPGs at the cell membrane. Using FRET between a Texas Red-labeled SDF-1 alpha and an enhanced green fluorescent protein-tagged CXCR4, we show that binding of SDF-1 alpha to cell surface HSPGs modifies neither the kinetics of occupancy nor activation in real time of CXCR4 by the chemokine. Moreover, attachment to HSPGs does not modify the potency of the chemokine to promote internalization of CXCR4. Attachment to cellular HSPGs may co-operate in the optimal anti-HIV activity of SDF-1 alpha by increasing the local concentration of the chemokine in the surrounding environment of CXCR4, thus facilitating sustained occupancy and down-regulation of the HIV coreceptor.


Subject(s)
Chemokines, CXC/pharmacology , Chemokines, CXC/physiology , HIV-1/drug effects , HIV-1/physiology , Heparan Sulfate Proteoglycans/physiology , Receptors, CXCR4/physiology , Cell Line , Chemokine CXCL12 , Humans , Virus Replication/drug effects
7.
AIDS Res Hum Retroviruses ; 16(13): 1259-67, 2000 Sep 01.
Article in English | MEDLINE | ID: mdl-10957723

ABSTRACT

The HIV-1 NCp7 contains two spatially close zinc fingers, required for the production of infectious particles. To investigate in more detail the function of the zinc finger domain, monoclonal antibodies were generated with a cyclic analog of the NCp7 proximal zinc finger. This analog was shown to bind zinc ions and to preserve the highly folded structure of the native peptide (Dong C-Z et al.: J Am Chem Soc 1995;117:2726-2731). We report here two monoclonal antibodies (2B10 and 4D3), which are the first monoclonal antibodies directed against CCHC NCp7 zinc fingers. Dot-blot experiments revealed that a few nanograms of synthetic NCp7 can be detected on a nitrocellulose membrane. Whereas 2B10 appears specific for an epitope located in sequence 19-27 of NCp7, 4D3 appears to be structurally specific. Immunocomplex affinities were evaluated, using BIAcore technology, to be up to 1 and 10 nM, respectively, for 2B10 and 4D3 in 100 mM NaCl. These antibodies were able to recognize NCp7 in the Gag polyprotein precursor and were shown to immunoprecipitate NCp7 from a cell supernatant. Moreover, NCp7-Vpr interaction mediated by the zinc fingers is inhibited by 2B10, emphasizing the role of these domains in the protein-protein complex. These results indicate that 2B10 and 4D3 behave as useful tools for studying both NC protein functions during the course of virion morphogenesis and the role played by its zinc finger domain at various steps in the retroviral life cycle.


Subject(s)
Antibodies, Monoclonal/biosynthesis , Antibodies, Monoclonal/immunology , Capsid Proteins , Capsid/immunology , Gene Products, gag/immunology , Viral Proteins , Amino Acid Sequence , Animals , Capsid/chemical synthesis , Capsid/chemistry , Enzyme-Linked Immunosorbent Assay , Epitope Mapping , Female , Gene Products, gag/chemical synthesis , Gene Products, gag/chemistry , Gene Products, vpr/immunology , Humans , Kinetics , Mice , Mice, Inbred BALB C , Molecular Sequence Data , Peptides, Cyclic/chemical synthesis , Peptides, Cyclic/immunology , Precipitin Tests , Protein Precursors/immunology , Surface Plasmon Resonance/methods , gag Gene Products, Human Immunodeficiency Virus
8.
Eur J Biochem ; 267(12): 3654-60, 2000 Jun.
Article in English | MEDLINE | ID: mdl-10848983

ABSTRACT

The basic viral protein R (Vpr) performs several functions during the human immunodeficiency virus HIV-1 retroviral cycle, including G2 mitosis arrest and nuclear import of the preintegration complex allowing lentivirus to replicate in nondividing cells. Accordingly, this protein was found in the nucleus of infected cells. In the virus, Vpr is incorporated through interaction with both nucleocapsid protein 7 (NCp7) and p6, two small proteins encoded by the C-terminal part of the Gag precursor. NCp7 is also involved in genomic RNA encapsidation during the budding process suggesting a possible interaction of Vpr with nucleic acids, either directly or via the NCp7 intermediate. Gel shift experiments were carried out with RNA and DNA using synthetic Vpr and peptide derivatives. The results show that Vpr binds to nucleic-acid inducing aggregates. This process, which requires the C-terminal basic domain of the protein (in particular the helical 70-80 domain), is regulated by the N-terminal region of Vpr. Moreover, NCp7 was shown to enhance RNA recognition by Vpr, a feature that could be required for Vpr encapsidation and during nuclear import of the preintegration complex.


Subject(s)
Capsid Proteins , DNA, Viral/metabolism , Gene Products, vpr/metabolism , RNA, Viral/metabolism , Viral Proteins , Amino Acid Sequence , Binding Sites , Capsid/metabolism , Gene Products, gag/metabolism , Gene Products, vpr/chemistry , HIV-1/genetics , Molecular Sequence Data , Peptide Fragments/chemistry , Peptide Fragments/immunology , Peptide Fragments/metabolism , gag Gene Products, Human Immunodeficiency Virus , vpr Gene Products, Human Immunodeficiency Virus
9.
Curr Biol ; 10(6): 325-8, 2000 Mar 23.
Article in English | MEDLINE | ID: mdl-10744978

ABSTRACT

HIV particles that use the chemokine receptor CXCR4 as a coreceptor for entry into cells (X4-HIV) inefficiently transmit infection across mucosal surfaces [1], despite their presence in seminal fluid and mucosal secretions from infected individuals [2] [3] [4]. In addition, although intestinal lymphocytes are susceptible to infection with either X4-HIV particles or particles that use the chemokine receptor CCR5 for viral entry (R5-HIV) during ex vivo culture [5], only systemic inoculation of R5-chimeric simian-HIV (S-HIV) results in a rapid loss of CD4(+) intestinal lymphocytes in macaques [6]. The mechanisms underlying the inefficient capacity of X4-HIV to transmit infection across mucosal surfaces and to infect intestinal lymphocytes in vivo have remained elusive. The CCR5 ligands RANTES, MIP-1alpha and MIP-1beta suppress infection by R5-HIV-1 particles via induction of CCR5 internalization, and individuals whose peripheral blood lymphocytes produce high levels of these chemokines are relatively resistant to infection [7] [8] [9]. Here, we show that the CXCR4 ligand stromal derived factor-1 (SDF-1) is constitutively expressed by mucosal epithelial cells at sites of HIV transmission and propagation. Furthermore, CXCR4 is selectively downmodulated on intestinal lymphocytes within the setting of prominent SDF-1 expression. We postulate that mucosally derived SDF-1 continuously downmodulates CXCR4 on resident HIV target cells, thereby reducing the transmission and propagation of X4-HIV at mucosal sites. Moreover, such a mechanism could contribute to the delayed emergence of X4 isolates, which predominantly occurs during the later stages of the HIV infection.


Subject(s)
Chemokines, CXC/physiology , HIV/growth & development , Intestinal Mucosa/metabolism , Chemokine CXCL12 , Chemokines, CXC/biosynthesis , Humans , Receptors, CCR5/metabolism , Receptors, CXCR4/biosynthesis , Receptors, CXCR4/genetics
10.
Am J Pathol ; 155(5): 1577-86, 1999 Nov.
Article in English | MEDLINE | ID: mdl-10550315

ABSTRACT

Stromal-cell derived factor or SDF-1 is a CXC chemokine constitutively expressed by stromal bone marrow cell cultures that binds to the G-protein-coupled receptor CXCR4. SDF-1/CXCR4 represents a unique, nonpromiscuous ligand/receptor pair that plays an essential role in prenatal myelo- and lymphopoiesis as well as in cardiovascular and neural development. SDF-1 prevents entry of CXCR4-dependent (X4) HIV viruses in T lymphocytes, by binding and internalizing CXCR4. The expression pattern of SDF-1 protein in normal tissues is not known. Here we describe an analysis of SDF-1 mRNA and protein in normal and inflamed skin by in situ hybridization and immunohistochemistry, using a novel anti-SDF-1 monoclonal antibody. We also describe the expression pattern of CXCR4 receptor by immunohistochemistry. Our results show that SDF-1 protein and mRNA are normally expressed by endothelial cells, pericytes, and either resident or explanted CD1a+ dendritic cells. Epithelial cells of sweat glands but not keratinocytes also express SDF-1. In various inflammatory skin diseases, a large number of mononuclear cells and fibroblasts in close contact with CXCR4-positive lymphocytic infiltrates also express SDF-1. CXCR4 was also detected in many different normal cell types, including endothelial and epithelial cells, which points to a role for SDF-1/CXCR4 cell signaling in vascular and epithelial homeostasis. The demonstration of SDF-1 expression in dendritic and endothelial cells provides new insights into the mechanisms of normal and pathological lymphocyte circulation and makes it possible to envisage a role for locally secreted SDF-1 in the selective incapacity of mucosal dendritic cells to support and propagate infection by X4 HIV isolates.


Subject(s)
Chemokines, CXC/biosynthesis , Dendritic Cells/metabolism , Endothelium, Vascular/metabolism , Skin/metabolism , Chemokine CXCL12 , Humans , Immunohistochemistry , Microcirculation , Microscopy, Confocal , Pericytes/metabolism , Receptors, CXCR4/biosynthesis , Skin/blood supply , Skin/pathology
11.
Proc Natl Acad Sci U S A ; 96(15): 8585-90, 1999 Jul 20.
Article in English | MEDLINE | ID: mdl-10411919

ABSTRACT

The chemokine stromal cell-derived factor 1 (SDF-1) stimulates the growth of pre-B cells in vitro, and mice with a disrupted SDF-1 gene have abnormal fetal liver B cell lymphopoiesis. The origin of SDF-1 production has not been determined yet. Using an anti-SDF-1 mAb, we performed immunohistochemical studies in four human embryos and five fetuses to define which cells express the SDF-1 protein at sites of antenatal B cell lymphopoiesis. All mesothelial cells contained SDF-1 at all stages of development, including in the intraembryonic splanchnopleuric mesoderm early into gestation. In fetal lungs and kidneys, SDF-1 was expressed by epithelial cells, and a few B lymphoid precursors, expressing V pre-B chains, were also detected. In the fetal liver, in addition to mesothelial cells, biliary epithelial cells were the only cells to contain SDF-1. Pre-B cells expressing V chains were abundant and exclusively located around the edge of portal spaces, in close contact with biliary ductal plate epithelial cells. They did not colocalize with biliary collecting ducts. Biliary ductal plate epithelial cells and liver B cell lymphopoiesis display a parallel development and disappearance during fetal life. These results indicate that early B cell lymphopoiesis in the splanchnopleura may be triggered by mesothelial cells producing SDF-1. Later into gestation, biliary ductal plate epithelial cells may support B cell lymphopoiesis, thus playing a role similar to that of epithelial cells in the avian bursa of Fabricius, and of thymic epithelial cells for T cell lymphopoiesis.


Subject(s)
B-Lymphocytes/metabolism , Bile Ducts/embryology , Chemokines, CXC/metabolism , Amino Acid Sequence , Cell Differentiation , Chemokine CXCL12 , Chemokines, CXC/immunology , Embryonic and Fetal Development , Enzyme-Linked Immunosorbent Assay , Epithelial Cells/metabolism , Epithelium/embryology , Gestational Age , Humans , Immunohistochemistry , Liver/embryology , Lung/embryology , Molecular Sequence Data
12.
J Virol ; 73(7): 5411-21, 1999 Jul.
Article in English | MEDLINE | ID: mdl-10364288

ABSTRACT

The rotavirus nonstructural protein NSP3 is a sequence-specific RNA binding protein that binds the nonpolyadenylated 3' end of the rotavirus mRNAs. NSP3 also interacts with the translation initiation factor eIF4GI and competes with the poly(A) binding protein. Deletion mutations and point mutations of NSP3 from group A rotavirus (NSP3A), expressed in Escherichia coli, indicate that the RNA binding domain lies between amino acids 4 and 149. Similar results were obtained with NSP3 from group C rotaviruses. Data also indicate that a dimer of NSP3A binds one molecule of RNA and that dimerization is necessary for strong RNA binding. The dimerization domain of NSP3 was mapped between amino acids 150 and 206 by using the yeast two-hybrid system. The eukaryotic initiation factor 4 GI subunit (eIF-4GI) binding domain of NSP3A has been mapped in the last 107 amino acids of its C terminus by using a pulldown assay and the yeast two-hybrid system. NSP3 is composed of two functional domains separated by a dimerization domain.


Subject(s)
Peptide Initiation Factors/metabolism , RNA/metabolism , Rotavirus/metabolism , Viral Nonstructural Proteins/metabolism , Animals , Binding Sites , Cattle , Cell Line , Cloning, Molecular , Dimerization , Disulfides , Escherichia coli , Gene Expression , Haplorhini , Peptide Initiation Factors/genetics , Point Mutation , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism , Saccharomyces cerevisiae , Swine , Viral Nonstructural Proteins/genetics
13.
Virology ; 248(2): 394-405, 1998 Sep 01.
Article in English | MEDLINE | ID: mdl-9721247

ABSTRACT

The binding of HIV-derived recombinant soluble (s)gp120 to the CD4(+)/CXCR4(+) A3.01 T cell line inhibits the binding of the CXCR4-specific monoclonal antibodies 12G5, which interacts with the second extracellular loop, and 6H8, which binds the NH2 terminus. We have used this as an assay to analyse the interaction of recombinant sgp120 from diverse viral origins with CXCR4. The strength of the interaction between sgp120 and CXCR4 correlated with sgp120 affinity for the CD4-CXCR4 complex, and the interaction of sgp120MN and sgp120IIIB with CXCR4 was highly dependent on the level of CD4 expressed on a variety of different T cell lines. sgp120 from X4, R5X4, and R5 viruses interacted with CXCR4, although the R5 sgp120-CXCR4 interactions were weaker than those of the other gp120s. The interaction of sgp120IIIB or sgp120MN with CXCR4 was inhibited by neutralizing monoclonal antibodies that prevent the sgp120-CD4 interaction but also by antibodies specific for the gp120 V2 and V3 loops, the CD4-induced epitope and the 2G12 epitope, which interfere weakly or not at all with CD4-sgp120 binding. The binding to A3.01 cells of wild-type sgp120HxB2, but not of sgp120 deleted in the COOH and NH2 termini, interfered with 12G5 binding in a dose-dependent manner. Further deletion of the V1 and V2 loops restored CXCR4 binding activity, but additional removal of the V3 loop eliminated the gp120-CXCR4 interaction, without decreasing the affinity between mutated sgp120 and CD4. Taken together, these results demonstrate that the interactions between sgp120 and CXCR4 are globally similar to those previously observed between sgp120 and CCR5, with some apparent differences in the strength of the sgp120-CXCR4 interactions and their dependence on CD4.


Subject(s)
CD4 Antigens/metabolism , HIV Envelope Protein gp120/metabolism , Receptors, CXCR4/metabolism , Antibodies, Monoclonal/immunology , Blotting, Western , Cell Line , Conserved Sequence , Gene Deletion , HIV Envelope Protein gp120/chemistry , Humans , Membrane Glycoproteins/immunology , Neutralization Tests , Peptide Fragments/metabolism , Protein Conformation , Receptors, CXCR4/immunology , Tumor Cells, Cultured
14.
J Biol Chem ; 272(49): 30753-9, 1997 Dec 05.
Article in English | MEDLINE | ID: mdl-9388214

ABSTRACT

The 96-amino acid protein Vpr functions as a regulator of cellular processes involved in human immunodeficiency virus, type 1 (HIV-1) life cycle, in particular by interrupting cells division in the G2 phase. Incorporation of Vpr in the virion was reported to be mediated by the C-terminal domain of the Pr55(Gag) polyprotein precursor, which includes NCp7, a protein involved in the genomic RNA encapsidation and p6, a protein required for particle budding. To precisely define the Gag and Vpr sequences involved in this protein-protein interaction, NCp7, p6, and Vpr as well as a series of derived peptides were synthesized using Fmoc (N-(9-fluorenyl)methoxycarbonyl) chemistry. Binding assays were carried out by Far Western experiments and by competition studies using (52-96)Vpr immobilized onto agarose beads. The results show that interaction between NCp7 and Vpr occurs in vitro by a recognition mechanism requiring the zinc fingers of NCp7 and the last 16 amino acids of Vpr. Moreover, NCp10, the equivalent of NCp7 in Moloney murine leukemia virus but not polysine inhibits Vpr-NCp7 complexation. Interestingly enough, Vpr was found to interact with Gag, NCp15, and NCp7 but not with mature p6 in vitro. In vivo mutations in NCp7 zinc fingers in an HIV-1 molecular clone led to viruses with important defects in Vpr encapsidation. Together, these results suggest that NCp7 cooperates with p6 to induce Vpr encapsidation in HIV-1 mature particles. The NCp7-Vpr complex could also be important for interaction of Vpr with cellular proteins involved in cell division.


Subject(s)
Capsid Proteins , Capsid/metabolism , Gene Products, gag/metabolism , Gene Products, vpr/metabolism , Viral Proteins , Zinc Fingers , Amino Acid Sequence , Binding Sites , Capsid/genetics , Gene Products, gag/genetics , Gene Products, vpr/genetics , Humans , Magnetic Resonance Spectroscopy , Molecular Sequence Data , Mutagenesis, Site-Directed , Virion/genetics , Virion/metabolism , gag Gene Products, Human Immunodeficiency Virus
15.
J Biol Chem ; 271(13): 7465-72, 1996 Mar 29.
Article in English | MEDLINE | ID: mdl-8631775

ABSTRACT

The COOH-terminal Src kinase (Csk) is responsible for the phosphorylation of the conserved, negative regulatory, carboxyl-terminal tyrosine of most of the Src family protein tyrosine kinases. Up to now, no stable binding of Csk to Src kinases has been detected. We therefore decided to analyze this interaction using two systems which allow detection of transient interaction. We produced and purified recombinant proteins in the glutathione S-transferase prokaryotic expression system. First, using real-time biospecific interaction analysis (BIAcore(TM)), we detected in vitro a specific interaction between Csk and one of its substrates Lck, a lymphocyte-specific member of the Src family. This interaction requires the autophosphorylation of Lck on tyrosine 394 (the phosphorylation of which is correlated with an increase of the kinase activity) and involves a functional Csk SH2 domain. Second, using the yeast two-hybrid system, we confirmed in vivo the physical interaction between Csk and Lck. Furthermore, in vitro we showed that autophosphorylation of Lck on tyrosine 394 enhances the phosphorylation of Lck by Csk on the negative regulatory site, tyrosine 505, suggesting that activated Lck serves preferentially as substrate for Csk. These findings might explain the mechanism(s) by which Csk interacts with most of Src kinases to down-regulate their kinase activity.


Subject(s)
Protein-Tyrosine Kinases/chemistry , Protein-Tyrosine Kinases/metabolism , src Homology Domains , src-Family Kinases/chemistry , src-Family Kinases/metabolism , Amino Acid Sequence , Binding Sites , CSK Tyrosine-Protein Kinase , Conserved Sequence , Glutathione Transferase/biosynthesis , Kinetics , Lymphocyte Specific Protein Tyrosine Kinase p56(lck) , Molecular Sequence Data , Mutagenesis, Site-Directed , Peptide Fragments/chemistry , Peptide Fragments/isolation & purification , Peptide Mapping , Phosphopeptides/chemistry , Phosphopeptides/isolation & purification , Phosphorylation , Point Mutation , Protein-Tyrosine Kinases/isolation & purification , Recombinant Fusion Proteins/chemistry , Recombinant Fusion Proteins/isolation & purification , Recombinant Fusion Proteins/metabolism , Two-Hybrid System Techniques , Tyrosine , src-Family Kinases/isolation & purification
16.
J Gen Virol ; 76 ( Pt 10): 2457-66, 1995 Oct.
Article in English | MEDLINE | ID: mdl-7595349

ABSTRACT

The nucleocapsid protein NCp15 of human immunodeficiency virus type 1 (HIV-1) is a small basic protein with two zinc fingers. It is required for virion morphogenesis and synthesis of proviral DNA. As the first step in our study of the structural domains involved in the various functions of this protein, 18 monoclonal antibodies (MAbs) were isolated. The epitopes of NCp7 recognized by the MAbs were mapped using synthetic peptides representing overlapping sequences and truncated forms of NCp7. These anti-NCp7 MAbs were investigated by ELISA and real-time biospecific interaction analysis (BIAcore). Five classes of anti-NCp7 MAbs were characterized. Three classes (14 MAbs) were directed against continuous epitopes, one in the N-terminal part, another next to the second zinc finger and the third in the C-terminal part of the protein. Two other classes comprised four MAbs reacting only with the entire NCp7 and not with any of the small overlapping peptides used, suggesting that these MAbs were directed against conformational epitopes. The anti-NCp7 MAbs directed against linear epitopes were able to react efficiently with both NCp7 and NCp15, the NCp7 precursor, whereas the anti-NCp7 MAbs directed against conformational epitopes did not react with NCp15. Interestingly, most of the anti-NCp7 MAbs directed against conformational epitopes were capable of inhibiting the tight interaction between NCp7 and the HIV-1 replication primer tRNA(Lys,3). In contrast, most of the MAbs directed against linear epitopes did not inhibit this interaction.


Subject(s)
Antibodies, Monoclonal , Capsid Proteins , Capsid/chemistry , Gene Products, gag/chemistry , HIV Antibodies , HIV-1/immunology , Nucleocapsid Proteins , Protein Conformation , Viral Proteins , Amino Acid Sequence , Animals , Antigen-Antibody Reactions , Binding, Competitive , Biosensing Techniques , Capsid/immunology , Epitope Mapping , Female , Gene Products, gag/immunology , Humans , Mice , Mice, Inbred BALB C , Molecular Sequence Data , Peptides/chemical synthesis , Protein Precursors/chemistry , RNA, Transfer, Lys/analysis , Rats , Zinc Fingers/immunology , gag Gene Products, Human Immunodeficiency Virus
17.
Virology ; 204(1): 8-16, 1994 Oct.
Article in English | MEDLINE | ID: mdl-7522377

ABSTRACT

An automated biosensor system designed for measuring molecular interactions in real-time (BIAcore) was used to characterize monoclonal antibodies (Mabs) raised against the inner capsid protein (VP6) of the bovine rotavirus (RF strain). Six Mabs, all reactive in Western blot and in indirect immunofluorescence assays, were mapped, using purified recombinant VP6. These Mabs were delineated into several groups of antibodies. Interactions of selected monoclonal antibodies with purified viral particles were studied by the BIAcore methodology. We showed that some Mabs did not react with single-shelled particles. Conversely, several Mabs reacted with single-shelled particles and one antibody reacted with both single-shelled and double-shelled particles. The latter Mab seemed to interact with VP6 through the holes of the outer capsid and its interaction with the double-shelled particles induced a significant decapsidation. These results allowed a better characterization of the epitopes of VP6. The localization of the epitopes in the viral particle is discussed in comparison with a pepscan study that determined the reactivity of Mabs with nested heptapeptides derived from the whole VP6 molecule.


Subject(s)
Antibodies, Monoclonal/immunology , Antigens, Viral/analysis , Capsid Proteins , Capsid/immunology , Rotavirus/immunology , Amino Acid Sequence , Animals , Antigen-Antibody Reactions , Antigens, Viral/immunology , Biosensing Techniques , Capsid/chemistry , Cattle , Epitopes/analysis , Kinetics , Molecular Sequence Data , Recombinant Proteins/chemistry , Recombinant Proteins/immunology , Refractometry/methods , Virion/immunology
18.
AIDS Res Hum Retroviruses ; 10(8): 983-93, 1994 Aug.
Article in English | MEDLINE | ID: mdl-7529035

ABSTRACT

Retroviral nucleocapsid (NC) proteins are highly basic, with one or two zinc fingers, and are required for virion formation, genomic RNA dimerization and packaging, and replication primer tRNA annealing to the viral RNA. We report here the first characterization of monoclonal antibodies directed against a retroviral nucleocapsid protein and their use to study the structure-function relationships of the nucleocapsid protein NCp7 of HIV-1. Four anti-NCp7 monoclonal antibodies (MAbs) have been generated by using NCp7 of HIV-1. The epitope targets of these MAbs were mapped using ELISA and BIAcore techniques. Whereas three of them are specific for epitopes located in the N and C termini of NCp7, the fourth one appears to be conformation specific. Interestingly, only two of these MAbs, the conformation-specific one and the MAb recognizing an N-terminal epitope are able to inhibit the RNA-binding and annealing activities of NCp7 as well as strong-stop DNA synthesis in vitro. The binding of the two other MAbs onto NCp7 either has no effect or enhances the NCp7-RNA interactions. These MAbs also display a differential recognition of the Gag polyprotein precursor, which makes them useful tools for studying NC protein maturation in the course of virion morphogenesis.


Subject(s)
Antibodies, Monoclonal/immunology , Capsid Proteins , Capsid/metabolism , Gene Products, gag/metabolism , HIV Antibodies/immunology , RNA, Viral/metabolism , Viral Proteins , Zinc Fingers , Amino Acid Sequence , Antibody Specificity , Antigen-Antibody Reactions , Capsid/chemistry , Capsid/immunology , DNA, Viral/biosynthesis , Epitope Mapping , Gene Products, gag/chemistry , Gene Products, gag/immunology , HIV Reverse Transcriptase , HIV-1/immunology , Molecular Sequence Data , Peptides/chemical synthesis , Peptides/metabolism , Protein Conformation , Protein Precursors/metabolism , RNA, Transfer, Lys/metabolism , RNA, Viral/chemistry , RNA-Directed DNA Polymerase/metabolism , gag Gene Products, Human Immunodeficiency Virus
20.
Infect Immun ; 60(8): 3468-71, 1992 Aug.
Article in English | MEDLINE | ID: mdl-1639519

ABSTRACT

The 65-kDa gonococcal parietal lectin (GPL) has been purified and found to have a lectinlike activity exhibiting both structural and immunological similarities to the common antigen family. Ultrastructural localization of GPL was done by using anti-GPL monoclonal antibodies: GPL is a major component of the outer membrane and is also present in blebs formed by gonococci.


Subject(s)
Antigens, Bacterial/analysis , Lectins/analysis , Neisseria gonorrhoeae/immunology , Antibodies, Monoclonal/immunology , Cross Reactions , Lectins/immunology
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