PubMed Health⌕ Search

Biomedical subjects

C Devaux

Publications and source records attributed to C Devaux.

At least 91 records · Page 5Linked to original sources
PubMed1995

Functional epitope analysis of the human CD4 molecule: antibodies that inhibit human immunodeficiency virus type 1 gene expression bind to the immunoglobulin CDR3-like region of CD4.

We recently demonstrated that monoclonal antibody (MAb) 13B8-2, specific for the immunoglobulin (Ig) complementary determining region 3 (CDR3)-like region of the CD4 molecule, inhibits viral transcription in human immunodeficiency virus (HIV)-infected CEM cells and HIV type 1 (HIV-1) promoter activity. Here, we have studied the capacity of several MAb specific for the D1 domain of CD4, including anti-CDR2-like (Leu-3a and ST4) and anti-CDR3-like (13B8-2 and ST40) MAb, and for the D2 domain of CD4 (BL4) to inhibit both provirus transcription in HIV-1LAI-infected CEM cells and transcription of the chloramphenicol acetyltransferase (CAT) gene under control of the HIV-1 long terminal repeat in transiently transfected CEM cells. We found that HIV-1 promoter activity and provirus transcription are inhibited only by MAb that bind to the CDR3-like region in domain 1 of CD4. Moreover, we demonstrated that the Fab fragment of an anti-CDR3-like region-specific anti-CD4 MAb is a powerful inhibitor of HIV-1 promoter activity. These results have implications for understanding the role of the CDR3-like region in CD4 T-cell signaling, which controls provirus transcription.

Antibodies, Monoclonal↗
PubMed1995

The cytoplasmic tail of CD4 is required for inhibition of human immunodeficiency virus type 1 replication by antibodies that bind to the immunoglobulin CDR3-like region in domain 1 of CD4.

Monoclonal antibodies (MAb) directed against the immunoglobulin complementary determining region 3 (CDR3)-like region of the CD4 molecule inhibit human immunodeficiency virus type 1 (HIV-1) transcription. We report here data showing that the cytoplasmic tail of CD4 is required for such inhibition to be achieved. To this aim, we studied the effect of MAb 13B8-2 treatment on (i) HIV-1 production in A2.01 cells, which express different forms of the CD4 gene, (ii) Tat-induced HIV-1 promoter activation, and (iii) mitogen-activated protein kinase (MAPK) activation, which is induced in CD4-positive cells by HIV-1 cross-linking of CD4. Inhibition of HIV production by 13B8-2 MAb treatment was consistently observed in cells expressing wild-type CD4 and cells expressing a hybrid CD4-CD8 molecule (amino acids 1 to 177 of CD4 fused to the hinge, transmembrane, and cytoplasmic domains of CD8). However, no delay in HIV-1 production was observed in cells expressing a truncated CD4 which lacks the cytoplasmic domain (CD4.401). Chloramphenicol acetyltransferase assays demonstrated that Tat-dependent activation of the HIV-1 long terminal repeat promoter was inhibited by MAb 13B8-2 in A2.01/CD4 and A2.01/CD4-CD8 but not in A2.01/CD4.401 cells. Finally, we found that MAb 13B8-2 treatment inhibited the activation of MAPK induced in A2.01/CD4 and A2.01/CD4-CD8 following cross-linking of CD4 by HIV-1.

Antibodies, Monoclonal↗
PubMed1994

The cytoplasmic domain of CD4 plays a critical role during the early stages of HIV infection in T-cells.

The role played by the cytoplasmic domain of the CD4 molecule in the process of HIV infection was investigated, using A2.01 cells which express different forms of the CD4 gene. A delay in HIV production was consistently observed in cells expressing a truncated CD4 which lacks the cytoplasmic domain (CD4.401) compared with cells expressing the wild type CD4. The delay was much less in cells expressing a hybrid CD4-CD8 molecule (amino acids 1-177 of CD4 fused to the hinge, transmembrane and cytoplasmic domains of CD8). Yet the extent of viral entry and reverse transcription, monitored by semi-quantitative PCR, was similar in each cell type studied. For further study of the mechanism responsible for delayed HIV replication in the A2.01/CD4.401 cell line, cells were treated with phytohaemagglutinin (PHA), 24 h after HIV infection. Under such experimental conditions HIV production was detected at the same time in the culture supernatants of A2.01/CD4 and A2.01/CD4.401 cells. Moreover, we found that CD4 oligomerization by HIV-1 induced NF-kappa B translocation in A2.01/CD4 and A2.01/CD4-CD8 but not in A2.01/CD4.401 cells. This was consistent with CAT assay experiments which provided evidence for Tat-independent NF-kappa B mediated activation of HIV-1 LTR promoter after HIV binding to CD4 in A2.01/CD4 and A2.01/CD4-CD8 but not in A2.01/CD4.401 cells. In contrast to results published recently by Tremblay et al. (1994, EMBO J., 13, 774-783), we propose that a positive cellular signal initiated following oligomerization of the CD4 by the virus itself is involved in NF-kappa B-dependent early HIV transcription in A2.01/CD4 cells.

Base Sequence↗
PubMed1994

Jacalin, a lectin with anti-HIV-1 properties, and HIV-1 gp120 envelope protein interact with distinct regions of the CD4 molecule.

Jacalin is a multimeric plant lectin able to interact with the lymphocyte cell-surface molecule CD4, a known receptor for the human immunodeficiency virus type 1 (HIV-1). Moreover, jacalin is able to block HIV-1 infection of CD4+ lymphoblastoid cells. Here we studied whether jacalin prevents HIV-1 gp120-CD4 interactions. We found (i) that jacalin did not inhibit HIV-1 Lai-induced syncytium formation that requires gp120-CD4 interactions; (ii) that jacalin prevented neither rgp120 binding to cell-surface CD4 nor sCD4 binding to viral envelope proteins expressed at the surface of HIV-1-infected lymphoblastoid cells; (iii) that jacalin did not compete for binding to CD4 with anti-CD4 mAb specific for the CDR2- or CDR3-like regions of the D1 domain of CD4; (iv) that jacalin did not bind a recombinant soluble molecule containing the D1/D2 domains of CD4; and, (iv) that jacalin binding to CD4 is inhibited by sugars known to interact with the lectinic-site of jacalin. These data have implications for the understanding of the mechanism by which jacalin blocks HIV-1 infection of CD4+ cells.

Acetylgalactosamine↗
PubMed1994

Involvement of human leukocyte antigen class I molecules in human immunodeficiency virus infection of CD4-positive cells.

We have studied the putative roles of human immunodeficiency virus (HIV)-associated and cell surface-expressed major histocompatibility complex class I (MHC-I) molecules in the course of the HIV life cycle by the combined use of MHC-I molecule-positive and MHC-I molecule-negative virus particles and MHC-I molecule-positive and MHC-I molecule-negative CD4+ human cells. We found (i) that several anti-MHC-I monoclonal antibodies neutralize cell infection by direct interaction with HIV-associated MHC-I antigens, (ii) that these HIV-associated MHC-I antigens are however dispensable for cell infection, and (iii) that the cell surface-expressed MHC-I molecules are unnecessary for productive infection of CD4+ human cells. These results clarify further the functions of MHC-I molecules during the HIV life cycle.

Antibodies, Monoclonal↗
PubMed1993

An antibody that binds the immunoglobulin CDR3-like region of the CD4 molecule inhibits provirus transcription in HIV-infected T cells.

We used the polymerase chain reaction (PCR) to study which step(s) of the human immunodeficiency virus type 1 (HIV-1) life cycle may be blocked following treatment of HIV-exposed CEM cells with 13B8-2, a monoclonal antibody (mAb) specific for the immunoglobulin (Ig) CDR3-like region of the CD4 molecule and able to inhibit the productive infection of CEM cells by HIV-1. The presence of viral RNA was investigated and found in 13B8-2 mAb-treated CEM cells 30 min after viral exposure; the full-length viral DNA was found at 24 h post-infection. We also found integrated forms of viral DNA at 24 h post-infection. However, the integrated provirus was transcriptionally inactive in 13B8-2 mAb-treated cells, as demonstrated by the absence of spliced HIV-1 mRNA. The lack of HIV transcription under 13B8-2 mAb treatment was confirmed by chloramphenicol acetyltransferase (CAT) assay. We conclude that the inhibition of viral gene transcription accounts for the lack of progeny virions in culture supernatants of cells treated with this anti-CD4 mAb. We also demonstrate that 13B8-2 blocks viral production from chronically infected cells and restores CD4 cell-surface expression on CEM cells containing an integrated provirus(es). We found this effect to be reversible. Moreover, we demonstrate that 13B8-2 mAb treatment is efficient on different HIV-1 and HIV-2 virus isolates. These results may have major implications for the treatment of AIDS.

Antibodies, Monoclonal↗
PubMed1993

Ig CDR3-like region of the CD4 molecule is involved in HIV-induced syncytia formation but not in viral entry.

The HIV1 envelope glycoprotein gp120 binding site has been previously mapped by genetic studies to the CDR2-like region of the first domain of the CD4 molecule. mAb reactive with epitopes linked to this region (e.g., OKT4A) inhibit both HIV entry into CD4-positive cells and syncytia formation. A second area of this domain, the CDR3-like region, has been shown to be involved in gp120-CD4 interactions, but its role remained so far unclear. We show here that a mAb specific for the CDR3-like region of the CD4 receptor, 13B8-2, actually blocks soluble gp120 binding to CD4, inhibits HIV-induced cell-cell fusion, and prevents viral production by infected cells. However, this mAb fails to inhibit the binding of viral particles to cell-surface CD4 and their entry into CD4-positive cells. These results strongly suggest i) that soluble gp120 and virion-anchored gp120 bind CD4 in distinct manners, ii) that gp120-CD4 interactions required for viral entry and syncytia formation are different, and iii) that mAb binding to the CDR3-like region of the first domain of CD4 affects a post-entry step of the HIV replicative cycle.

Antibodies, Monoclonal↗
PubMed1993

Antibodies cross-reactive with the scorpion-toxin II from Androctonus australis Hector elicited in mice by a synthetic peptide.

With the aim of developing active protection against the noxious effects provoked in humans by scorpion stings, the possibility of eliciting toxin reactive antibodies by immunization with a short peptide was assessed in mice. The amino acid sequence of residues 50 to 59 of Androctonus australis Hector toxin II was chosen, on the basis of previous results indicating that rabbit anti-(50-59) antibodies neutralize the biological effects of the parent toxin. The peptide was prepared by solid-phase synthesis procedures and used in different forms (free, linearly polymerized, coupled to KLH, coupled to a low-molecular weight B-lymphocyte activator) in order to immunize groups of non-congenic NMRI or congenic C57BL/6 mice. The reactivities of each serum with the peptide and with the toxin were assessed in ELISA. Strong reactivities with both the peptide (mean titer over 1:52,600) and the toxin (mean titer 1:800) were observed in all mice from the group that received the KLH-coupled peptide. However, mouse immune sera failed either to recognize the toxin in a liquid-phase radioimmunoassay or to neutralize the lethal effects of the toxin. The requirements, in terms of affinity and recognition of native conformation, for anti-peptide antibodies to display neutralizing properties are discussed.

Amino Acid Sequence↗
PubMed1993

Fine molecular analysis of the antigenicity of the Androctonus australis hector scorpion neurotoxin II: a new antigenic epitope disclosed by the Pepscan method.

A set of 58 overlapping rod-bound peptides was used to map the antigenic reactivity pattern of a 64-residue neurotoxin (AaH II) from the venom of the scorpion Androctonus australis hector. Five anti-toxin rabbit antisera were assayed serially for their capacity to bind to each peptide in the set. Six regions of antigenic reactivity were thus identified (sequences: 1-8, 4-12, 27-35, 39-45, 52-58 and 55-61). When positioned on a 3-D model of the toxin, these regions appeared to correspond to either beta-turn or extended parts of the molecule. The antigenic regions revealed by this technique agree fairly well with those previously mapped on the same toxin by different methods. One discrepancy was, however, that the present study shows the N-terminus to be strongly reactive with anti-toxin antibodies. The antigenicity of this region was confirmed, since rabbit antibodies raised against a synthetic peptide mimicking the sequence 1-8 of the toxin were found to bind the toxin with high efficiency. A fine analysis of the recognition of this region was performed. Alanine-containing analogs of the sequence 1-7 and peptides mimicking the N-terminal of the four main toxins of AaH were probed with anti-toxin and anti-peptide antibodies. Lysine 2, aspartic acid 3 and glycine 4 were shown to be key residues in the recognition of the N-terminal region of the AaH II toxin by anti-toxin antibodies. In contrast, a loose specificity of recognition was shown by one anti-peptide serum which was, in addition, able to recognize the N-termini of all four AaH toxins.

Amino Acid Sequence↗
PubMed1992

Monoclonal antibodies to toxin II from the scorpion Androctonus australis Hector: further characterization of epitope specificities and neutralizing capacities.

The epitope specificities of two previously prepared monoclonal antibodies (mAb) to the toxin II from Androctonus australis Hector were characterized. Neither mAb 4C1 nor mAb 3C5 was able to recognize any of the 58 overlapping synthetic heptapeptides which cover the whole sequence of toxin II. Thus, both mAbs probably recognize conformation-dependent epitopes at the surface of the toxin. Experiments were designed to check whether or not the two mAbs, or their Fab fragments, were able to bind simultaneously to the toxin. The results indicated that the epitopes recognized by the two antibodies are probably close together at the surface of the toxin, thus preventing the simultaneous binding of both mAbs to a single toxin molecule. Given the proximity of the two epitopes and the fact that mAb 4C1 is known to be a neutralizing antibody, the capacity of mAb 3C5 to inhibit the toxic effects of the toxin was re-evaluated in C57BL/6 mice. A clear, but weak, neutralizing effect was found, consistent with the low affinity binding of the mAb in the proximity of a neutralizing site of the toxin.

Animals↗
PubMed1992

Subtyping of human immunodeficiency virus isolates with a panel of monoclonal antibodies: identification of conserved and divergent epitopes on p17 and p25 core proteins.

We have investigated the feasibility and significance of subtyping of human immunodeficiency virus (HIV) isolates with monoclonal antibodies (mAb) raised against the core proteins of HIV. A panel of 37 mAb tested for reactivity with HIV1 oligopeptides was used to analyse the antigenic relatedness among 14 HIV isolates which included 12 isolates of HIV1 from different geographical origins and 2 isolates of HIV2. Three out of these 37 mAb reacted with conserved epitopes expressed by all 14 HIV isolates tested. These reagents which included 2 mAb reacting with the 285-310 amino acid sequence of p25 and 1 mAb reacting with an epitope of p25 not mapped by the peptides' approach, also reacted with a non-human primate lentivirus. Five mAb reacting either with the 11-25 or 121-132 amino acid sequences of p17 or the 302-320 amino acid sequence of p25 reacted with strain-specific epitopes. The other 29 mAb reacted with polymorphic epitopes and thereby define subfamily and subtype-specific markers.

Antibodies, Monoclonal↗
PubMed1992

Clonal analysis of murine B cell response to the human immunodeficiency virus type 1 (HIV1)-gag p17 and p25 antigens.

The antigenicity of HIV-gag p17 and p25 proteins was analyzed using a panel of 52 monoclonal antibodies (mAb) derived from 17 independent fusion experiment protocols performed in 12 different laboratories. These mAb were tested for their capacity to bind peptides corresponding to sequences of HIV1-BRU-gag p17 and p25. Thirty-five overlapping peptides (P1 to P35) totally covering the p17 and p25 proteins were used. This study allowed us to identify four immunodominant regions inducing B cell response, two on p17 corresponding to P2 and P13 (amino acids 11-25 and 121-132, respectively) and two on p25 corresponding to P21 and P28-P29-P30 (a.a. 201-218 and 285-320 respectively). According to secondary structure predictions, peptides P2 and P21 contained hydrophilic alpha helix folded regions whereas P13 sequence presented a beta turn propensity. These regions and the P28-30 region were also predicted to be easily accessible to mAb. Several other p25-derived peptides: P15 (a.a. 142-156), P16 (a.a. 148-162), P19 (a.a. 176-192), P22 (a.a. 219-233) and P23 (a.a. 233-253) were recognized by mAb. No p17-derived peptide other than P2, P13 and P12 (a.a. 111-123) was found to react with mAb. Cross-blocking studies between mAb, suggested the existence of more than four distinct epitopic areas on p17 and eight on p25.

Amino Acid Sequence↗
PubMed1992

Poly(L-lysine)-conjugated oligonucleotides promote sequence-specific inhibition of acute HIV-1 infection.

Previously, we have reported that conjugation of antisense oligonucleotides to poly(L-lysine) (PLL) lowers their inhibitory concentration in several biological models. We have now tested these conjugates for inhibition of human immunodeficiency virus type 1 (HIV-1) replication. PLL-conjugated oligonucleotides complementary to the translation initiation site of Tat protein protect cells from the cytopathic effect of HIV-1 in acute infection assays. The EC50 of conjugates is approximately 0.15 microM, which represents a strong reduction in concentration as compared to nonconjugated oligonucleotides (EC50 = 20 microM). In contrast with most reports in the literature, we have observed sequence specific antiviral effects with PLL conjugates. This was particularly noteworthy in antiviral experiments performed with HIV-1 isolates presenting heterogeneity in the 5' end of the tat mRNA sequence. Two mismatches at the target site were sufficient to reduce very significantly the antiviral activity of the conjugates but did not modify the effect of nonconjugated oligonucleotides. Unlike free oligonucleotides, PLL-conjugated ones do not interfere with virus penetration and/or reverse transcription as demonstrated by polymerase chain reaction (PCR) analysis of viral DNA.

Animals↗
PubMed1991

Crystallization and preliminary X-ray diffraction data of the Fab fragment of a monoclonal antibody against apamin, a bee venom neurotoxin.

Fab fragments of anti-apamin monoclonal antibodies have been purified to homogeneity and crystallized. The crystals belong to the monoclinic space group P21 with cell dimensions a = 99.0 +/- 0.3 A, b = 137.1 +/- 0.4 A, c = 76.0 +/- 0.2 A and beta = 92.9 +/- 0.9 degrees. They most likely contain four molecules in the asymmetric unit (Vm = 2.39 A3/Da). The possibility of the existence of non-crystallographic symmetry is discussed.

Antibodies, Monoclonal↗
PubMed1991

Characterization of monoclonal antibodies identifying type and strain-specific epitopes of human immunodeficiency virus type 1.

Several hybridoma cell lines were raised against the highly cytopathic Zaïrian isolate of Human Immunodeficiency Virus (HIV), HIV1-NDK. The specificity of the secreted monoclonal antibodies (mAb) was demonstrated by immunoblotting, radioimmunoprecipitation and immunofluorescence. Two hybridoma cell lines secreted mAb reacting with independent epitopes of the NDK p17 capsid protein and its precursors. One, RL16.24.5, is specific for the NDK isolate whereas the other, RL16.45.1, along with anti-p25 RL16.30.1 mAb, bind all HIV1 isolates but not HIV2. Together with the previously described mAb RL4.72.1 those reagents define lentivirus subfamily (HIV1, HIV2, SIV) type/subtype (HIV1) and strain (HIV1-NDK) specific epitopes expressed on HIV1-NDK core proteins. The last mAb RL16.76.1 binds the env gene products gp160 and gp120.

Animals↗
PubMed1991

Expression of an immunogenic region of HIV by a filamentous bacteriophage vector.

Vectors derived from the Escherichia coli filamentous phage, fd-tet, expressing parts of the human immunodeficiency virus (HIV) gag genes were constructed and analyzed. The immunoreactive domain of HIV Gag antigens was produced in the form of a fusion protein, with a phage minor coat protein, called protein III, playing an important role in phage infectivity. A micropanning procedure, utilizing the strong affinity of biotinylated antibody to streptavidin, was applied for the selection of clones. A simple preparation procedure consisting of polyethyleneglycol precipitation of the recombinant phage from the E. coli supernatant allowed us to detect HIV antigens by enzyme-linked immunosorbent assay (ELISA). Cloned FUSE-gag, as isolated using anti-Gag RL4.72.1 monoclonal antibody (mAb), contained a nucleotide sequence coding for 91 amino acids of HIV Gag p24. It specifically reacted with the mAb in the ELISA. Construction of the mAb-selectable phages permitted localization of epitopes for mAb. Infectivity of the phage clone was specifically neutralized by the anti-HIV mAb. Immunoelectroblotting analysis of recombinant phages revealed the presence of an about 65-kDa band reacting with anti-HIV mAb. This Mr corresponded to the size of the fused form of the FUSE 1 protein III. Human sera from HIV-infected and uninfected individuals reacted with recombinant protein III, as well as the original form of protein III.

Amino Acid Sequence↗