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S Benichou

Publications and source records attributed to S Benichou.

32 records · Page 2Linked to original sources
PubMed1996

Interaction between the cytoplasmic domains of HIV-1 Vpu and CD4: role of Vpu residues involved in CD4 interaction and in vitro CD4 degradation.

The Vpu and CD4 cytoplasmic domains were found, by using a two-hybrid assay in yeast, to interact in the absence of their membrane anchor domains. Studies on several deletion and point mutants revealed that the overall structure of the Vpu cytoplasmic domain is required for this interaction. The Vpu amino acid residues involved in the interaction with CD4 were identified. Deletion of the C-terminal residues of Vpu, required for CD4 degradation, as well as the double mutation on the casein kinase II phosphorylation sites S52N-S56N, also involved in CD4 degradation, resulted in the loss of interaction with CD4 and in the inability to induce CD4 degradation. These results suggest that the ability of Vpu to mediate the degradation of CD4 is linked to its capacity to physically interact with CD4. However, additional mutagenesis on the S52 site revealed that the interaction between the cytoplasmic domains of Vpu and CD4 is not sufficient for in vitro Vpu-mediated CD4 degradation.

Amino Acid Sequence↗
PubMed1996

Human immunodeficiency virus type 1 Vpr protein binds to the uracil DNA glycosylase DNA repair enzyme.

The role of the accessory gene product Vpr during human immunodeficiency virus type 1 infection remains unclear. We have used the yeast two-hybrid system to identify cellular proteins that interact with Vpr and could be involved in its function. A cDNA clone which encodes the human uracil DNA glycosylase (UNG), a DNA repair enzyme involved in removal of uracil in DNA, has been isolated. Interaction between Vpr and UNG has been demonstrated by in vitro protein-protein binding assays using translated, radiolabeled Vpr and UNG recombinant proteins expressed as a glutathione S-transferase fusion protein. Conversely, purified UNG has been demonstrated to interact with Vpr recombinant protein expressed as a glutathione S-transferase fusion protein. Coimmunoprecipitation experiments confirmed that Vpr and UNG are associated within cells expressing Vpr. By using a panel of C- and N-terminally deleted Vpr mutants, we have determined that the core protein of Vpr, spanning amino acids 15 to 77, is involved in the interaction with UNG. We also demonstrate by in vitro experiments that the enzymatic activity of UNG is retained upon interaction with Vpr.

Animals↗
PubMed1994

Physical interaction of the HIV-1 Nef protein with beta-COP, a component of non-clathrin-coated vesicles essential for membrane traffic.

Nef is a 27-kDa myristylated protein conserved in most human immunodeficiency virus (HIV)-1, HIV-2, and simian immunodeficiency virus isolates. Simian immunodeficiency virus Nef is required in macaques for both high viral load and full pathological effects. Nef down-regulates the cell surface expression of CD4 by a post-translational mechanism that is not yet fully elucidated. We have used the yeast two-hybrid system to identify cellular proteins that interact with Nef. A cDNA was isolated which encodes a COOH-terminal fragment of human beta-COP, a major coat component of non-clathrin-coated vesicles. Nef and beta-COP interacted in vitro and were found to be physically associated in HIV-1-infected cells by co-immunoprecipitation. These observations suggest that beta-COP might be one of the cellular mediators of Nef function in HIV-1-infected cells.

Amino Acid Sequence↗
PubMed1994

Characterization and mapping of a B-cell immunogenic domain in hepatitis C virus E2 glycoprotein using a yeast peptide library.

To identify conserved humoral antigenic determinants within the hepatitis C virus (HCV) envelope protein E2, we expressed a peptide library containing random short fragments of the HCV envelope in yeast. Clones were identified using a monospecific rabbit antibody to a region downstream of the E2 hypervariable region. The clones define the limits of two original antigenic domains: a major one (aa 493-576) and a minor one (aa 535-606). The major antigenic domain maps in a region that displays a high degree of homology within a (HCV) subtype (92-97.6% identity). Yeast-encoded determinants were characterized by Western blot analysis, N-glycosidase F digestion, and using a panel of synthetic peptides. The data suggest that the major antigenic domain contains at least two determinants, one of them mimicked by an 18-mer peptide (aa 514-531). ELISA and competitive inhibition assays demonstrated that: (1) the determinants appear subtype 1a-specific, (2) seroprevalence of antibody to the determinants is rather low (20.6%), and (3) donors show a heterologous response to the different determinants. Antibody response to the E2 determinants was studied in HCV-infected chimpanzees and post-transfusion-associated NANB hepatitis cases. The antibody response was found during chronic infection and may not be effective for virus clearance.

Amino Acid Sequence↗
PubMed1994

Specificity of antipeptide antibodies produced against V2 and V3 regions of the external envelope of human immunodeficiency virus type 2.

The V2 region of simian immunodeficiency virus (SIV) and V3 region of human immunodeficiency virus type 1 (HIV-1) have been reported to be neutralization epitopes. We analysed the corresponding regions in HIV-2. Synthetic peptides modeling the V2 (aa 149-168) and V3 (CV3: aa 298-315 and NV3: aa 306-324) regions of the HIV-2 external envelope glycoprotein were coupled to KLH and used as immunogens in rabbits. We characterized the resulting antiV2 and antiV3 antibodies for their ability to recognize native and deglycosylated HIV-2 envelope glycoprotein, to block gp-CD4 interaction and to inhibit syncytium formation in vitro. The three synthetic peptides induced antibodies able to recognize specifically the native HIV-2 envelope glycoprotein with a significant avidity (K0.5 between 6 x 10(-7) and 8 x 10(-9) M). Interestingly, the reactivity of antibodies produced against the V2 peptide, which contains two potential sites of N-glycosylation, was higher against the fully deglycosylated than glycosylated HIV-2 external envelope glycoprotein (gp105). The antipeptide antibodies were used to investigate the topography of these regions in the preformed gp-CD4 complex in indirect immunofluorescence assays. The V2 and V3 regions in the complex remained accessible to their respective antibodies. Moreover, preincubation of gp105 with anti V2 or anti V3 antibodies did not prevent gp-CD4 interaction. Thus the V2 and V3 regions are not directly involved in the gp105 binding site for the CD4 receptor. Finally, in contrast with results obtained with antibodies produced against the V3 region of HIV-1 gp120 and monoclonal antibodies produced against the V3 of SIV, antibodies produced against V2 and V3 of HIV-2 were unable to inhibit syncytium formation induced by HIV-2 in vitro.

Amino Acid Sequence↗
PubMed1994

Characterization of monoclonal antibodies to human immunodeficiency virus type 2 envelope glycoproteins.

Twelve murine monoclonal antibodies (MAbs) to human immunodeficiency virus type 2 (isolate ROD) envelope glycoproteins have been generated and characterized. Nine MAbs were specific to the external gp125 and three reacted with the transmembrane gp36. A large majority of MAbs displayed a significant affinity for the native gp140 precursor and were shown to bind to viral antigens on the surface of fixed HIV-2-infected cells. In Western blot analysis, the 12 MAbs showed varying profiles of cross-reactivity, but none of the MAbs cross-reacted with the HIV-1LAI envelope. Six MAbs reacted exclusively with the homologous HIV-2ROD isolate whereas only two MAbs displayed cross-reactivity with HIV-2ROD, HIV-2EHO, and SIVmac251. The four other MAbs cross-reacted with either HIV-2EHO or SIVmac251. Results of competitive binding assays indicated that the three anti-gp36 MAbs shared the same competition group, whereas at least eight competition groups were defined with the nine anti-gp125 MAbs. The epitopes of the three anti-gp36 and four anti-gp125 MAbs have been delineated using synthetic peptides or by immunological screening of an SIVmac251 peptide library expressed in yeast. The anti-gp36 MAbs are directed against the same domain of the transmembrane gp36 corresponding to the major antigenic determinant of HIV-2 and HIV-1. The four anti-gp125 MAbs recognize four distinct epitopes localized in the V2, V3, and C1 domains. None of the 12 MAbs displayed neutralizing activity against HIV-2ROD, including the 2 MAbs directed against the V2 and V3 domains.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

Expression of HTLV-I Env and Tax recombinant peptides in yeast: identification of immunogenic domains.

A peptide library of HTLV-I Env and Tax proteins was constructed in yeast in order to characterize which domains of these proteins are immunogenic in HTLV-I-infected individuals. Five yeast colonies (A to E) were selected using HTLV-I positive plasma, and one yeast colony (F) was selected using rabbit anti-Tax sera. Plasmid DNA present in each positive clone was recovered and sequenced. Overlapping clones A to E covered the C-terminal part of the gp46 exterior glycoprotein (aa 197 to 305) and were all glycosylated. Clone F encoded the C-terminal 25 aa of Tax (aa 329-353). Recombinant peptides were recognized by more than 40% of the HTLV-I positive human sera, confirming that they are major immunodominant domains. We studied the antibody response to each recombinant peptide in patients with TSP/HAM and asymptomatic carriers. Higher absorbance values were obtained with sera from TSP/HAM patients than from asymptomatic carriers, but the difference between the two groups was not statistically significant. Our study confirms that the COOH-terminal region of gp46 is highly immunogenic in HTLV-I-infected individuals and demonstrates a new immunogenic epitope of the Tax protein.

Amino Acid Sequence↗
PubMed1993

Characterization of B-cell epitopes in the envelope glycoproteins of simian immunodeficiency virus.

We identified previously a neutralizing epitope in the V2 domain of the simian immunodeficiency virus (SIVmac) external envelope protein. The present study reports identification of five additional linear epitopes of SIVmac (isolate 251) by immunological screening of a peptide library expressed in yeast, using SIVmac-infected macaque sera. Three epitopes were localized in the envelope glycoproteins and the two others in the reverse transcriptase and in the Rev regulatory protein. Antibody response against the four envelope epitopes was monitored for 2 years in 12 macaques experimentally infected by SIVmac251. These four envelope regions represent major immunodominant epitopes of the SIVmac. Two epitopes are located in the V3 domain (a.a. 311-330) of the external gp130 and near the amino terminal part (a.a. 601-619) of the transmembrane gp36, in regions similar to those identified in HIVs, demonstrating immunological similarities between the envelopes of SIVs and HIVs. SIV-specific immunodominant epitopes were also identified in the V1 (a.a. 111-130) and V2 (a.a. 171-190) domains of the external gp130. In particular, antibody response against the V2 neutralizing region seems to play some role in the control of disease progression in SIVmac-infected macaques.

Amino Acid Sequence↗
PubMed1992

Identification of a neutralizing domain in the external envelope glycoprotein of simian immunodeficiency virus.

Two murine monoclonal antibodies (MAbs), designated MATG2014 and MATG2033, were generated. They are reactive with the external envelope glycoprotein gp130 of the simian immunodeficiency virus of macaque monkey (SIVmac251), and display a cell-free virus neutralizing activity in vitro. In addition, MATG2014 cross-reacts with HIV-2Rod gp140. Epitope mapping of these MAbs was performed by screening and SIVmac peptide library expressed in yeast and confirmed using synthetic peptides. MATG2014 and MATG2033 recognize two overlapping epitopes localized in an 18 residue domain between amino acid 171 and 188 of the SIVmac251 gp130. Sera from experimentally SIV-infected macaques are immunoreactive with this neutralizing domain. Sequence comparison with related SIV and HIV-2 viral strains indicates a low variability of this region, consistent with the cross-reactivity of MATG2014 with HIV-2Rod gp140. This domain should then be considered in designing experimental vaccines.

Amino Acid Sequence↗
PubMed1984

[Relation between personality and spastic angina].

The personalities of 60 patients suffering from episodes of retrosternal pain were evaluated by means of psychological tests ( Cattel 's questionnaire and Eysenck's personality inventory) and semi-directive interviews. The patients fell into three groups: group I patients (n = 21) had atheromatous lesions of the coronary arteries detected at angiography; group II patients (n = 19) had normal or subnormal coronary arteries, but angiography demonstrated arterial spasm; group III patients (n = 20) had angiographically normal coronary arteries without spasm. A statistically significant difference (p less than 0.05) was noted between groups I and II, but not between groups II and III. Eleven of the 21 patients in group I presented with an obsessional personality which was not found in groups II and III where 13/19 and 16/20 patients respectively had a hysterical personality.

Adult↗
PubMed1982

[Medium-stay for geriatric patients: a long-stay waiting room or an active rehabilitation unit?].

From May 1979 to April 1980, 223 patients were discharged from a "medium stay" unit (mean length of stay: 45 days) for geriatric patients in Bordeaux (France). The outcome at discharge was established from retrospective data, and the long-term outcome (18 months) through a letter sent to general practitioners (rate of response: 88,5% with, in some instances, a prompting phone-call). The mortality rates were 22,5% in hospitalized patients and 38% in survivors after discharge. When those hospitalized for social reasons only are excluded, 62,9% of the remaining patients returned to their former place of residence at discharge. Moreover, 83% were still living at the same place after 18 months (range: 12-24 months). Considering the patients' ages and the seriousness of their conditions, "medium stay", geriatric units seem efficient in helping to maintain the aged at home.

Aged↗
PubMedDate not supplied

[Aspects of pneumocystosis seen in a French pneumonology department in 1987-1988].

Over a 2 years' period, 49 AIDS patients and 3 non AIDS patients were treated for pneumocystosis in our chest department. Forty-six were male and 6 were female. Pneumocystosis was the first opportunistic infection in 77 p 100 of patients. Fever above 38.5 degrees C was the major symptom in 92 p 100. Cough was present in 90 p 100 and dyspnoea in 94 p 100. Clinical symptoms had begun 21.7 +/- 15.7 days before diagnosis. Mean PaO2 value was 50.9 +/- 15.7 mmHg. Forty-eight patients were initially treated by daily intravenous administration of trimethoprim 960 mg and sulfamethoxazole 4,800 mg. Three patients received a pentamidine aerosol and one received DFMO. Treatment was effective in 39 patients; 11 patients died between the 5th and the 29th days of treatment; 2 had an early relapse. Fever disappeared after 9.8 +/- 6.6 days, and blood gases returned to normal within 10.8 +/- 7.7 days. All patients whose PaO2 was above 56 mmHg were cured. Thus, the trimethoprim-sulfamethoxazole combination proved active in the treatment of pneumocystosis. Other treatments are useful in case of side-effects or failure of the initial therapy. Failures can be suspected on the fourth day of treatment and in such cases CMV co-infection must be looked for and treated.

Acquired Immunodeficiency Syndrome↗