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Biomedical subjects

L Montagnier

Publications and source records attributed to L Montagnier.

At least 55 records · Page 3Linked to original sources
PubMed1995

Inhibition of in vitro HIV infection by trinitrophenyl-protein conjugates.

Levels of natural antibodies (NAb) with high anti-trinitrophenyl (TNP) activity are increased during human immunodeficiency virus (HIV) infection. The aim of the present study was to examine the anti-HIV effect of natural anti-TNP antibodies, as well as that of their internal image, TNP antigen, on HIV infection in vitro. The results obtained with anti-TNP antibodies, as assessed by syncytia formation, were variable, although they demonstrated an inhibitory effect. In contrast, using RT activity assay plus evaluation of syncytia formation and the viral cytopathic effect, we found that bovine serum albumin (BSA) bearing different TNP groups was able to inhibit HIV infection of peripheral mononuclear cells and T4 cell lines without affecting cell metabolism or proliferation. BSA alone was devoid of activity; the antiviral effect depended on TNP substitution of the BSA molecule, and passage through an anti-TNP immunoadsorbent abolished this effect. The mechanism by which TNP exerts this antiviral effect is unclear. Antigenic epitopes may be shared by HIV and TNP, since monoclonal antibodies directed against various HIV proteins reacted with TNP in an enzyme immunoassay. TNP-BSA, however, did not bind to the CD4 receptor.

Animals↗
PubMed1995

Low susceptibility of resident microglia to simian immunodeficiency virus replication during the early stages of infection.

To assess the susceptibility of resident microglia to simian immunodeficiency virus (SIV) infection, we analysed the brains of rhesus macaques after intracerebral (i.c.) inoculation of the virus into the central region at 7 days, 1, 2 and 3 months post-inoculation (p.i.). The brains of animals showed the same moderate neuropathological changes in central, frontal and parietal regions of the brain, characterized by gliosis, microglial nodules, perivascular infiltrates and occasional white matter pallor and similar low numbers of infected cells detected by in situ hybridization. These results, showing that i.c. inoculation did not lead to preferential infection of brain tissue, even near the inoculation point at 7 days p.i., provide evidence for the low susceptibility of resident microglia to SIV replication during the early stages of infection.

Animals↗
PubMed1995

In vitro influence of Mycoplasma penetrans on activation of peripheral T lymphocytes from healthy donors or human immunodeficiency virus-infected individuals.

Mycoplasma penetrans is a mycoplasma species newly isolated from the urine of human immunodeficiency virus (HIV)-infected individuals and presents the only case in which an association has been found between antibodies against a mycoplasma and HIV infection. To further explore the effects of M. penetrans on the immune system, we studied the influence of this mycoplasma on peripheral blood mononuclear cells (PBMCs) from healthy donors and HIV-infected individuals. M. penetrans induced, in addition to blastogenesis of PBMCs, a significant proliferative response associated with the expression of some activation markers such as CD69, HLA-DR, and CD25. This M. penetrans-dependent lymphocyte activation was observed not only in healthy donors but also in HIV-infected persons at different stages of the disease. In addition, our study revealed that both CD4+ and CD8+ T lymphocytes were responsive to M. penetrans. Interestingly, the mitogenic activity of M. penetrans was associated with mycoplasma cells but not with the supernatants of mycoplasma culture. The potent stimulating activity of M. penetrans on T lymphocytes from HIV-infected individuals is of particular interest in view of the supposed contribution of immune activation to HIV replication and disease progression.

Antigens, CD↗
PubMed1994

Isolation and envelope sequence of a highly divergent HIV-1 isolate: definition of a new HIV-1 group.

We report here the isolation and envelope sequence of a divergent HIV-1 isolate from a French woman with AIDS. This virus, HIV-1VAU, is closely related to the recently described Cameroonian viral isolates HIV-1ANT70 and HIV-1MVP5180, until now designated HIV-1 subtype O. Phylogenetic analysis reveals that the three viruses are equidistant from one another and that their mutual divergence is similar to what has been reported between the more conventional HIV-1 subtypes. Therefore, these three viruses could be included in a new viral group, HIV-1 group O (outgroup), distinct from the cluster of other HIV-1 isolates, which we will refer to as group M (Major group). The HIV-1 group O is currently emerging in western central Africa but its spread in Europe has already started.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Kex2p: a model for cellular endoprotease processing human immunodeficiency virus type 1 envelope glycoprotein precursor.

The endoproteolytic cleavage of the envelope glycoprotein precursor (gp160) of the human immunodeficiency virus type 1 (HIV-1) by a cellular protease is required for full activation of the virus. In this study, processing of gp160 was analyzed in vitro using the Kex2p endoprotease from the yeast Saccharomyces cerevisiae as a processing enzyme model. Endoproteolytic processing was examined using a synthetic peptide that mimics the cleavage site of HIV-1 glycoprotein, and a recombinant gp160 bearing the entire sequence of the env gene product, including the conserved cleavage site Arg508-Glu-Lys-Arg511. Coexpression in BHK-21 of Kex2p and gp160 by recombinant vaccinia viruses demonstrates that Kex2p can correctly process the HIV-1 glycoprotein to gp120 and gp41. Furthermore, recombinant gp160 and peptide were used as substrates and subjected to proteolysis with purified membranes from an S. cerevisiae strain overproducing the Kex2p endoprotease. Treatment of recombinant gp160, which has an apparent molecular mass of 127 kDa, with Kex2p and Western blot analysis showed that the precursor was cleaved into two products of about 101 and 34 kDa apparent molecular mass. Amino acid sequencing of the NH2-terminus of the 34-kDa product showed that the cleavage site of recombinant gp160 was between Arg511 and Ala512. Recombinant gp160 mutated at the sequence coding for the potential cleavage site, and mature recombinant gp120, however, were not cleaved when treated with Kex2p. In summary, our results show that Kex2p cleaves both the HIV-1 envelope glycoprotein precursor and a synthetic peptide mimicking the cleavage site of HIV-1 gp160 at the dibasic site, suggesting functional analogy between yeast Kex2p and the cellular protease responsible for the maturation of HIV-1 envelope glycoproteins in infected human cells.

Amino Acid Sequence↗
PubMed1994

Effects of calcium ions on proteolytic processing of HIV-1 gp160 precursor and on cell fusion.

Complete activation of human immunodeficiency virus type 1 (HIV-1) requires the endoproteolytic cleavage by cellular protease of the envelope glycoprotein precursor (gp160) into the external glycoprotein gp120, and the transmembrane glycoprotein gp41. We report here the effect of depletion of cellular calcium ions on maturation of precursor gp160 and its concomitant effect on syncytium formation. We show that the cellular endoprotease activity responsible for gp160 maturation and the capacity for HIV-1 to induce syncytium formation are calcium-dependent. In addition, we show that endoproteolytic maturation is a key step in syncytium formation induced by HIV-1.

Amino Acid Sequence↗
PubMed1994

Selective anergy of V beta 8+ T cells in human immunodeficiency virus-infected individuals.

We have analyzed the V beta usage by CD4+ and CD8+ T cells from human immunodeficiency virus (HIV)-infected individuals in response to an in vitro stimulation with the superantigenic erythrogenic toxin A (ETA) of Streptococcus pyogenes. ETA amplifies specifically CD4+ and CD8+ T cells from control donors expressing the V beta 8 and the V beta 12 elements. When peripheral T cells from asymptomatic HIV-infected individuals were stimulated with ETA, there was a complete lack of activation of the V beta 8+ T cell subset, whereas the V beta 12+ T cell subset responded normally to the superantigen. This V beta-specific anergy, which was also observed in response to staphylococcal enterotoxin E (SEE), affected both CD4+ and CD8+ T cells and represented an intrinsic functional defect rather than a specific lack of response to bacterial superantigens since it was also observed after a stimulation with V beta 8 monoclonal antibodies. The V beta 8 anergic T cells did not express interleukin 2 receptors (IL-2Rs) and failed to proliferate in response to exogenous IL-2 or IL-4, suggesting that this anergy was not a reversible process, at least by the use of these cytokines. The unresponsiveness of the V beta 8 T cell subset is frequent since it was found in 56% of the patients studied, and comparison of the clinical status of responder vs. anergic patients indicated that the only known common factor between them was HIV infection. In addition, it is noteworthy that the anergy of the V beta 8 subset may be a very early phenomenon since it was found in a patient at Centers for Disease Control stage I of the disease. These data provide evidence that a dominant superantigen may be involved in the course of HIV infection and that the contribution of HIV has to be considered.

Adult↗
PubMed1994

Different proliferative response of human and chimpanzee lymphocytes after contact with human immunodeficiency virus type 1 gp120.

T cell functional defects are a common aspect of human immunodeficiency virus (HIV) infection. Moreover, it has been suggested that indirect mechanisms are involved in CD4+ cell depletion. Unresponsiveness to proliferative stimuli of lymphocytes incubated with HIV particles or with viral proteins is well documented. Nevertheless, drawing a clear picture of the anergy phenomenon is difficult because of several unresolved and controversial questions. Here we report that recombinant gp120 induces anergy in T helper lymphocytes cultured with different stimuli. The proliferative responses to interleukin (IL)-2, IL-4, IL-6, anti-CD2, anti-CD3 and phorbol 12-myristate 13-acetate are inhibited. Moreover, anergic cells show a different distribution in cell cycle phases as compared to control cells, leading us to suggest that the progression in the cell cycle is hampered and that a pre-mitotic block takes place. Furthermore, since chimpanzees are susceptible to HIV-1 infection without showing immunodeficiency signs, we analyzed the proliferation of chimpanzee lymphocytes without observing anergy in cells preincubated with gp120. Taken together, these results support the hypothesis that anergy plays an important role in HIV infection in vivo.

Animals↗
PubMed1994

Development of PCR-based assays for the detection of two human mollicute species, Mycoplasma penetrans and M. hominis.

Recently, a 16S rDNA-based polymerase chain reaction (PCR) assay was developed for the selective and sensitive detection of Mycoplasma pirum. In this study, the same procedure was used in order to selectively detect by PCR two human mycoplasmas, M. hominis and M. penetrans, with a high level of sensitivity even in a context of human DNA. For each assay, the specificity was verified by testing DNA from other mollicute species (including those closely related to the corresponding mycoplasma), from bacteria phylogenetically close to mollicutes, from Escherichia coli and from human peripheral blood mononuclear cells (PBMCs). Each assay proved to be highly sensitive since it reliably detected 10 DNA molecules, even in a context of human DNA. The results of this study demonstrate the suitability of our procedure using primers which were designed for the PCR detection of human mollicutes with a high specificity and a low and reproducible threshold of sensitivity.

Base Sequence↗
PubMed1994

HIV-2 EHO isolate has a divergent envelope gene and induces single cell killing by apoptosis.

The human immunodeficiency virus type 2 (HIV-2)-related isolate, referred to as HIV-2 EHO, has been isolated from an Ivory Coast patient with acquired immunodeficiency syndrome (AIDS). Infection of CD4 expressing cells with this highly infectious virus mediates a cytopathic effect characterized by single-cell killing as a consequence of apoptosis. Nucleotide sequence analysis of the HIV-2 EHO genome revealed a significant degree of divergence of its envelope gene from that of other known HIV-2 strains. This divergence for the deduced amino acid sequence corresponding to the extracellular envelope glycoprotein was 26 to 30%. These unique genetic and biological properties suggest that the HIV-2 EHO isolate is a distinct prototype in the HIV-2 family.

Acquired Immunodeficiency Syndrome↗
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

Inhibition of HIV type 1 reverse transcriptase assay by nucleases produced by contaminating mycoplasmas.

Mycoplasmal contamination of HIV-1-infected cells has been found to induce reduction of reverse transcriptase (RT) activity; however, the exact mechanism of this phenomenon was not clearly elucidated. Our results indicate that the apparent reduction in RT activity is due to a calcium-dependent nuclease(s) that is (are) produced by contaminating mycoplasmas. The interference with the RT assay was found to be due to the degradation of products of the RT activity. Addition of EGTA at a 1 mM concentration was sufficient to remove the inhibitory effect. The particular HIV-1-producing cell line that was under study was found to be contaminated with Mycoplasma fermentans and Mycoplasma pirum and the latter was isolated in pure culture. Nuclease activity was also observed with pure cultures of mycoplasmas from different species. The activity was found to be of the endonuclease type because it was active with both supercoiled and linear DNAs.

Cell Line↗
PubMed1994

Early stages of feline immunodeficiency virus infection in lymph nodes and spleen.

Analysis of the early stages of infection within the lymphoid organs is crucial for the understanding of the physiopathology of HIV infection. Such analysis can only be performed using animal models. Cats were infected with two strains of FIV and killed at regular intervals for a classic pathologic study along with a quantification of the viral load by in situ hybridization in the spleen and the lymph nodes. The pathological study showed a persistent follicular reaction, which peaked 15 days postinoculation (p.i.). The in situ hybridization study showed two types of labeling. The first was spot labeling corresponding to cells actively replicating the virus. The second consisted of a more diffuse labeling linked to the follicular dendritic cells (FDCs) demonstrating by colocalization of virus detected by in situ hybridization associated with the FDCs, specifically labeled by immunohistochemistry. The number of productive cells is few and identical for the two viruses tested. Despite a slight peak at 15 days p.i., the number of infected cells persists while slightly decreasing over time. The FDC virus load appears jointly with the appearance of antibody and remains permanent until the end of the study at 3 years p.i. These results show that in the FIV model, there is a chronic permanent infection in the lymphoid organs. Furthermore, as compared with the SIV-macaque model, there is a correlation between the low number of infected cells detected in these organs in the early phase and the extended length of the asymptomatic period, which contrasts with the high level of the FDC virus load lasting during the same period.

Animals↗
PubMed1994

Molecular characterization of the P1-like adhesin gene from Mycoplasma pirum.

A DNA fragment has been isolated from the genome of Mycoplasma pirum by use of a genetic probe derived from the conserved region within the genes for the major adhesins of Mycoplasma genitalium and Mycoplasma pneumoniae. A gene encoding an adhesin-like polypeptide was localized, and sequence analysis indicated a G + C content of only 28%, with A- and T-rich codons being preferentially used. A total of 91% of positions 3 were either A or T. The deduced polypeptide is 1,144 amino acids long (126 kDa) and shows 26% identity with the adhesins of M. genitalium and M. pneumoniae. Other features in common with these two membrane proteins include a similar hydropathic profile and a proline-rich C terminus. Antibodies were prepared by using as an immunogen a peptide derived from the C terminus of the M. pirum adhesin-like polypeptide and were found to recognize on immunoblots a 126-kDa polypeptide from an M. pirum cellular extract. The characterization of the adhesin-like gene is a first step toward a better understanding of the mechanisms allowing this human mycoplasma to attach to host cells.

Adhesins, Bacterial↗