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Query: UMLS:C0019693 (HIV)
170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Syncytium formation between HUT-78 cells persistently infected with human immunodeficiency virus type 1 (HIV-1) and uninfected CD4-bearing MOLT-4 or CEM cells results in a rapid destruction of the MOLT-4 or CEM cells. This syncytium formation is due to the interaction between the gp120 glycoprotein expressed by the persistently HIV-1-infected HUT-78 cells and the CD4 receptor present on MOLT-4 or CEM cells. A flow cytometric method has been applied to separate the infected (HUT-78) from the uninfected (MOLT-4, CEM) cell populations. This method is based on a modified DNA staining protocol which clearly shows the differences in DNA content between HUT-78 cells, on the one hand, and MOLT-4 or CEM cells, on the other hand. Using this flow cytometric method we have demonstrated that those compounds (i.e., sulfated polysaccharides, aurintricarboxylic acid) that interact with gp120 (of the HIV-infected cells) or CD4 (of the uninfected cells) suppress syncytium formation and concomitant destruction of the CD4+ cells.
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PMID:Flow cytometric method to monitor the destruction of CD4+ cells following their fusion with HIV-infected cells. 169 39

Antigenic mutants of HIV-1 were isolated from three plaque-cloned viruses by the resistance of the virus to neutralizing mAb 0.5 beta against V3 domain of viral gp120, when the viruses were passaged in the presence of the antibody. However, when chronically infected MOLT-4 cells were treated with 0.5 beta mAb, recovered viruses from the 0.5 beta-treated cells showed no antigenic changes. The extent of genomic variation among antigenically distinct isolates was examined by nucleotide sequencing, which revealed a few base substitutions in 0.5 beta-binding site of all mutants isolated. The predicted amino acid replacements within 0.5 beta reacting epitope (V3 domain) causing the altered antigenicity were also identified for each of three isolates. Particularly, in one of the mutants, the most conserved Gly-Pro-Gly-Arg region located at the center of the V3 domain was changed to Gly-Gln-Gly-Arg. The radioimmunoprecipitation and synthetic peptide analyses revealed that this Pro320----Gln substitution reduced the binding affinity with 0.5 beta, although other mutations observed in the other mutants did not affect the binding affinity in radioimmunoprecipitation. We also observed that nucleic acid substitutions in the V3 domain occurred frequently in the absence of 0.5 beta mAb during our in vitro acute infection system using MT-4 cells.
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PMID:Generation of neutralization-resistant HIV-1 in vitro due to amino acid interchanges of third hypervariable env region. 170 2

We have developed a series of murine monoclonal antibodies to a region of the 120 kD envelope glycoprotein (gp120) of human immunodeficiency virus type 1 (HIV-1). This region has previously been implicated as a site for virus neutralization by antisera raised to recombinant proteins and by antibodies made to full-length gp120 purified from virus. The antigen employed was a synthetic peptide containing 15 amino acids, representing amino acid residues 308-322, RIQRGPGRAFVTIGK, of env gp120 (HTLV-IIIB isolate). Five of the monoclonal antibodies raised to this antigen have reactivity with gp120 from divergent strains of HIV-1 in Western blot assays. The two of these five which were tested with live cells infected with the divergent HIV-1 isolates IIIB, MN, and RF were specifically reactive by fluorescence analyses with cells infected with the MN and IIIB isolates. Four of the five monoclonal antibodies blocked the fusion of IIIB-infected cells with uninfected MOLT-4 target cells. The monoclonal antibody most reactive with MN-infected cells by fluorescence, #5025A, blocked the fusion of MN-infected cells with uninfected MOLT-4 cells. Four of the five monoclonal antibodies neutralized the IIIB isolate of HIV-1 in vitro, but none neutralized the MN or RF isolates at the levels of antibody tested (less than or equal to 50 micrograms/ml). Taken together these data indicate that monoclonal antibodies to the immunodominant neutralizing domain of HIV-1 gp120 display different levels of group reactivity depending on the assay system being examined.
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PMID:HIV-1 neutralizing monoclonal antibodies induced by a synthetic peptide. 170 1

Aurintricarboxylic acid (ATA) was fractionated by a combination of dialysis, ultrafiltration, and gel permeation chromatography. The number average and weight average molecular weights of the ATA fractions were determined by the universal calibration method. The sulfonic acid analogue of ATA was prepared and separated in high and low molecular weight fractions. The phosphonic acid analogue of ATA was also synthesized. All of the ATA fractions were tested for prevention of the cytopathic effect of HIV-1 and HIV-2 in MT-4 cell culture as well as against HIV-1 in CEM cell culture. The abilities of the fractions and analogues to inhibit syncytium formation between HIV-1- and HIV-2-infected HUT-78 cells and uninfected MOLT-4 cells were evaluated. In addition, the fractions and analogues were tested for cytotoxicity in mock-infected MT-4 cells, prevention of the binding of the OKT4A monoclonal antibody to the CD4 receptor, inhibition of the binding of anti-gp120 monoclonal antibody to gp120, inhibition of attachment of HIV-1 virions to MT-4 cells, and inhibition of HIV-1 reverse transcriptase. In all of these assays except cytotoxicity, there was a correlation of potency with molecular weight. The higher the molecular weight, the higher the activity. Several of the lower molecular weight fractions of ATA, which bound to gp120 but not to CD4, prevented HIV-1 and HIV-2 cytopathicity. A similar profile was observed for the phosphonic acid analogue of ATA and the lower molecular weight fraction of the sulfonic acid analogue. The results on the ATA fractions indicate that the binding of ATA to gp120 in the absence of CD4 binding is sufficient for anti-HIV activity. The active compounds bind more avidly to gp120 than to CD4. The anti-HIV activity of the ATA fractions is due to inhibition of virus binding due to an interference with the gp120-CD4 interaction.
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PMID:Preparation and anti-HIV activities of aurintricarboxylic acid fractions and analogues: direct correlation of antiviral potency with molecular weight. 170 65

Several compounds corresponding to fragments of the schematic representation of the polymeric structure of aurintricarboxylic acid (ATA) have been prepared and tested for prevention of the cytopathic effect of HIV-1 and HIV-2 in MT-4 cell culture and HIV-1 in CEM cell culture. Both the triphenylcarbinol 3 as well as the triphenylmethane 5 were found to afford protection against the cytopathogenicity of HIV-2 in MT-4 cells and HIV-1 in CEM cells, but they were inactive against HIV-1 in MT-4 cells. Both substances were also found to inhibit syncytium formation when MOLT-4 cells were cocultured with HIV-2-infected HUT-78 cells, but were inactive in this assay against HIV-1-infected cells. When observed, the activity is generally moderate in degree of protection and requires concentrations in the 10(-4) molar range. In contrast to ATA, both of these substances were inactive when tested for prevention of the binding of the OKT4A monoclonal antibody to the CD4 receptor and also for inhibition of HIV-1 reverse transcriptase. These substances therefore appear act by a mechanism that is distinct from that of polymeric ATA. Several active and inactive structural analogues of 3 and 5 were also synthesized. The anti-HIV activity in this series seems to depend on the presence of anionic carboxylate groups, since the methyl esters 4, 6, and 12 were uniformly inactive. The diphenylmethanes 8, 14, 18, and 19 also reproducibly inhibited the cytopathic effect of HIV-1 in CEM cell culture.
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PMID:Synthesis and anti-HIV activities of low molecular weight aurintricarboxylic acid fragments and related compounds. 170 66

Biliverdin (BV) is a bile pigment having anti-allergic properties. We examined the effect of BV on human immunodeficiency virus type 1 (HIV-1) in vitro. BV completely inhibited the cytopathic effect of HIV-1 in MT-4 cells at concentrations of 22.2 micrograms/ml or more. This inhibitory effect was also observed when BV was present during the adsorption period of HIV-1. However, BV was cytotoxic to MT-4 cells at concentrations above 800 micrograms/ml. At a concentration of 66.7 micrograms/ml, BV completely inhibited syncytia formation by HIV-infected and uninfected MOLT-4 cells. Moreover, after exposure of HIV-1 particles to BV for 2 h, the infectivity of the virus was reduced in a dose-dependent manner. It is speculated that the anti-HIV activity of BV is due to direct inactivation of virions and inhibition of virus binding to target cells.
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PMID:In vitro anti-human immunodeficiency virus type 1 activity of biliverdin, a bile pigment. 171 37

Complestatin, an anti-complement agent, was shown to be a potent inhibitor of human immunodeficiency virus type 1 (HIV-1) infection in vitro. It inhibited HIV-1-induced cytopathicity and HIV-1 antigen expression in MT-4 cells; the 50% effective doses for these effects were 2.2 and 1.5 micrograms/ml, respectively. No toxicity for MT-4 cells was observed at concentrations up to 400 micrograms/ml. In addition, the agent inhibited the focus formation in HT4-6C cells (CD4-positive HeLa cells); the concentration for 50% focus reduction was 0.9 microgram/ml. HIV-1-induced cell fusion in cocultures of MOLT-4 cells and MOLT-4/HTLV-IIIB were also blocked by complestatin (the concentration for 50% cell fusion inhibition, 0.9 microgram/ml). Complestatin had no ability to inhibit HIV-1 reverse transcriptase activity. When MT-4 cells were pretreated with complestatin for 2 hrs prior to the exposure to HIV-1, the HIV-1-induced cytopathicity was markedly inhibited, while pretreatment of HIV-1 with the agent did not affect the infection. These results suggest that complestatin primarily interacts with cells and inhibits viral adsorption to the cell surface as well as adsorption of infected cells to adjacent cells.
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PMID:Inhibition of human immunodeficiency virus type-1-induced syncytium formation and cytopathicity by complestatin. 171 91

The processing and secretion of the envelope glycoproteins of human immunodeficiency virus type 1 (HIV-1) were studied in chronically infected T cells and in primary macrophages treated with an antiviral antibiotic brefeldin A (BFA). BFA blocks the egress of proteins from the endoplasmic reticulum and has a profound effect on the structure of cis/medial Golgi. In MOLT-3 cells infected with the IIIB strain of HIV-1 (MOLT-3/IIIB), BFA inhibited the intracellular processing of gp160. The secretion of envelope proteins from these cells was significantly inhibited in the presence of BFA. The gag proteins, on the other hand, were processed and secreted normally. BFA also inhibited the proteolytic processing of gp160 in primary macrophages infected with HIV-1. The infectivity of virus pelleted from the medium of MOLT-3/IIIB cells treated with BFA was markedly lower than that obtained from untreated cells. These results demonstrate that the proteolytic processing of gp160 in HIV-1-infected cells takes place after the glycoprotein exists the endoplasmic reticulum and that the transport of glycoprotein to the cell surface is required for assembly of complete HIV-1 particles.
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PMID:Brefeldin A inhibits the processing and secretion of envelope glycoproteins of human immunodeficiency virus type 1. 171 46

We established seven hybridoma clones producing monoclonal antibodies (MAbs) against the envelope transmembrane protein (TMP) of a Ghanian isolate of human immunodeficiency virus type 2 (HIV-2[GH-1]) from mice immunized with the detergent-disrupted purified whole virus. The MAbs were found to react with 35 kilodalton (kD) TMP of the HIV-2[GH-1] virus in a Western blot assay (WB). Two of these MAbs recognized 135 kD proteins in addition to TMP in the lysate of HIV-2[GH-1]-infected cells. Two other MAbs cross-reacted with viral components corresponding to TMPs of HIV-2ROD and SIVMAC isolates in a Western blot. Results of competitive binding assay suggest that there are at least three epitopes on a TMP molecule of the HIV-2[GH-1] isolate. The MAbs did not inhibit syncytium formation between HIV-2[GH-1]-infected MOLT-4 cells and MOLT-4 clone 8 cells, nor virus infection to MOLT-4 clone 8 cells.
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PMID:Production and characterization of mouse monoclonal antibodies against the transmembrane protein of a human immunodeficiency virus type 2. 172 59

In order to investigate how human immunodeficiency virus (HIV) gains entry to the placenta, we have performed in vitro experiments in which highly purified trophoblast cells isolated from term human placentas were examined for their susceptibility to HIV infection. Trophoblast cells were exposed to cell-free HIV-1 for up to 24 h, after which the cultures were monitored by p24 antigen capture assay, reverse transcriptase assay, and electron microscopy for evidence of virus uptake and replication. None was found. In the second series of experiments, trophoblast cells were cocultured with HIV-infected MOLT-4 cells for 24 h, stained using an anti-HIV antibody, and examined by immunofluorescence microscopy. The MOLT cells were strongly positive, as expected, but many trophoblast colonies also showed a punctate staining pattern. Examination of similar cultures using the electron microscope revealed MOLT cells adherent to trophoblast but no evidence of cell-cell fusion. Virions were observed in coated pits at the trophoblast cell surface and in endosomes or multivesicular bodies in the cytoplasm. These observations are consistent with an endocytosis-mediated mechanism of virus entry. Virions were also observed budding from the trophoblast plasma membrane, indicating that these cells can support HIV replication. To our knowledge, these results show for the first time that HIV can infect placental trophoblast cells in vitro. The results suggest that the placenta could become infected with HIV by the interaction of virus-infected maternal lymphocytes with syncytiotrophoblast bordering the maternal blood in the intervillous space.
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PMID:Cell-mediated infection of human placental trophoblast with HIV in vitro. 174 80

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