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

Previously it has been reported that cocultivation of human immunodeficiency virus type 1 (HIV-1)-infected cells with uninfected cells results in formation of multinuclear giant cells, generated via an interaction of gp120 on the surface of infected cells with CD4 on the uninfected cells. Formation of multinuclear giant cells as occurring in the presence of normal fetal calf serum was not observed when HIV-infected MOLT-4 or MOLT-3 cells (chronically infected with HTLV-IIIB) and uninfected cells were cocultured in both serum-free medium and fibrinogen-depleted serum. Addition of sera (human and rabbit) as well as of fibrinogen (human and bovine), fibronectin (human), and alpha-globulin (human), but not of albumin, transferrin or gamma-globulin to serum-free medium caused formation of multinuclear giant cells. In contrast, HIV production from MOLT-3 cells proceeds also in the absence of serum. In control experiments it was established that the cells maintained at reduced serum concentration, or in serum-free medium without or with fibrinogen are viable even though displaying a lower metabolic rate (ATP formation and DNA synthesis). From these findings we conclude that serum components (e.g., fibrinogen, fibronectin, and alpha-globulin) are absolutely required for syncytium formation but are not essential for virus release.
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PMID:Effect of serum components on syncytium formation and virus production by cells infected with human immunodeficiency virus in vitro. 159 58

A cell clone, L-2, which produces non-infectious doughnut-shaped human immunodeficiency virus type 1 (HIV-1) particles, was permissive for HIV-1 superinfection, which resulted in the production of infectious particles. The superinfection showed slow kinetics compared with primary HIV-1 infection of M10 cells, the parent of the L-2 cell clone. Inhibition studies on the superinfection of L-2 cells using several CD4-related reagents showed that the CD4 molecule was an essential component of the receptor for superinfection. Strong inhibitory effects were obtained using CD4 peptides such as CD4(68-130), which includes a portion homologous to the immunoglobulin third complementarity-determining region (CDR3), as well as recombinant soluble CD4. In contrast, a CD4(45-60) peptide, which includes most of the CDR2-related region, was not effective, although the Leu-3a monoclonal antibody (MAb), which recognizes a site near the CDR2-related region, did slightly, but significantly, delay the superinfection kinetics. Comparative flow cytometry of L-2 and M10 cells revealed that the cell surface of L-2 cells despite expressing HIV-1 env protein, reacted slightly with OKT4 or anti-CD4(68-130) MAb, but not with Leu-3a or OKT4A MAb. In contrast, no reaction was detected with any of these anti-CD4 MAbs on the surface of another HIV-1 superinfection-resistant cell clone, MOLT-#8IIIB-14, which expresses HIV-1 env proteins but does not produce infectious HIV-1 particles. These results strongly suggest that expression of the CD4 major receptor site for primary HIV-1 infection is preferentially decreased on the surface of L-2 cells, but that the OKT4 epitope and the nearby region corresponding to immunoglobulin CDR3 remain exposed on the cell surface. Consequently, the CD4 CDR3-related region could play a major role as the receptor for the superinfection reported here.
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PMID:Human immunodeficiency virus type 1 (HIV-1) superinfection of a cell clone converting it from production of defective to infectious HIV-1 is mediated predominantly by CD4 regions other than the major binding site for HIV-1 glycoproteins. 162 1

The alpha-(1-3)-D-mannose- and alpha-(1-6)-D-mannose-specific agglutinins (lectins) from Galanthus nivalis, Hippeastrum hybrid, Narcissus pseudonarcissus, and Listera ovata inhibited infection of MT-4 cells by human immunodeficiency virus types 1 and 2 (HIV-1 and HIV-2) and simian immunodeficiency virus at concentrations comparable to the concentrations at which dextran sulfate (molecular weight, 5,000 [DS-5000]) inhibits these viruses (50% effective concentration, 0.2 to 0.6 microgram/ml). Unlike DS-5000, however, the plant lectins did not inhibit the replication of other enveloped viruses, except for human cytomegalovirus (50% effective concentration, 0.9 to 1.6 microgram/ml). The plant lectins suppressed syncytium formation between persistently HIV-1- or HIV-2-infected HUT-78 cells and uninfected MOLT-4 (clone 8) cells at concentrations that were 5- to 10-fold lower than that required for DS-5000. Unlike DS-5000, however, the plant lectins did not inhibit HIV-1 binding to CD4+ cells. Combination of the plant lectins with DS-5000 led to a potent synergistic inhibition of HIV-1-induced cytopathogenicity in MT-4 cells and syncytium formation between HIV-infected HUT-78 cells and MOLT-4 cells. Our data suggest that alpha-(1-3)-D- and alpha-(1-6)-D-mannose-specific plant lectins interfere with an event in the HIV replicative cycle that is subsequent to the attachment of the virions to the cells (i.e., the fusion process).
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PMID:Alpha-(1-3)- and alpha-(1-6)-D-mannose-specific plant lectins are markedly inhibitory to human immunodeficiency virus and cytomegalovirus infections in vitro. 164 7

Chemically modified compounds of glycyrrhizin have been synthesized and evaluated for their inhibitory effect on the replication of human immunodeficiency virus type 1 (HIV-1) and herpes simplex virus type 1 (HSV-1). Among them, the 11-deoxo compound having a heteroannular diene structure at the C and D rings proved as active against HIV-1 as glycyrrhizin in MT-4 and MOLT-4 cells. It completely inhibited HIV-1-induced cytopathogenicity in both cell lines at a concentration of 0.16 mM. The compound was also effective against HSV-1 with a 50% inhibitory concentration of 0.5 mM [corrected].
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PMID:Antiviral activities of glycyrrhizin and its modified compounds against human immunodeficiency virus type 1 (HIV-1) and herpes simplex virus type 1 (HSV-1) in vitro. 164 87

Polyhydroxycarboxylates (MW: 3,800-14,000) derived from phenolic (PDP) compounds have been found to inhibit the cytopathicity of HIV-1 and HIV-2 in MT-4 cells at concentrations that are not toxic to the host cells. The PDP compounds also inhibited syncytium formation in cocultures of MOLT-4 cells with HIV-1- or HIV-2-infected HUT-78 cells. They also interfered with the binding of OKT4A/leu3a monoclonal antibody (mAb) to the CD4 receptor, the binding of anti-gp120 mAb to HIV-1 gp120, and attachment of HIV-1 virions to MT-4 cells. The anti-HIV activity in this series of compounds can be ascribed to inhibition of the gp120-CD4 interaction and seems to depend on the presence of the anionic carboxylate groups. Their mechanism of action is similar to that of the heterogeneous polymer aurintricarboxylic acid (ATA).
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PMID:Selective inhibitory activity of polyhydroxycarboxylates derived from phenolic compounds against human immunodeficiency virus replication. 167 77

2',3'-Dideoxyadenosine (ddAdo) and its deamination product 2',3'-dideoxyinosine (ddIno) (didanosine) inhibit the replication and infectivity of the human immunodeficiency virus (HIV) in a number of in vitro assay systems. Early clinical studies (phase I) have indicated a role for ddIno in the treatment of patients with severe HIV infection. In the present in vitro study, the formation in human T cells (MOLT-4, ATH8, and CCRF-CEM) of the pharmacologically active metabolite of ddIno and ddAdo, 2',3'-dideoxyadenosine-5'-triphosphate (ddATP), was found to be stimulated 2-4-fold by appropriate concentrations of inosinate dehydrogenase (IMPD) inhibitors such as ribavirin, tiazofurin, and mycophenolic acid. Concomitant with this increase in ddATP formation from ddIno was an increase in anti-HIV activity of this agent when it was combined with ribavirin in the ATH8 cell assay system and with tiazofurin in the MOLT-4 assay system. No change was noted in the intracellular concentration of the corresponding physiological deoxynucleoside-5'-triphosphate, dATP; positive correlation was observed, however, between the increase in ddATP formation from ddIno and the increase in intracellular IMP occurring as a consequence of IMPD inhibition. The results support the hypothesis that the stimulation of ddATP formation seen when ddIno is combined with ribavirin or other IMPD inhibitors is a consequence of an increased concentration of IMP, the major phosphate donor for the initial phosphorylation step in the anabolism of ddIno to ddATP, i.e., ddIno----ddIMP.
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PMID:Inhibitors of IMP dehydrogenase stimulate the phosphorylation of the anti-human immunodeficiency virus nucleosides 2',3'-dideoxyadenosine and 2',3'-dideoxyinosine. 167 50

A defective doughnut-shaped human immunodeficiency virus type 1 (HIV-1)-producing cell clone (designated as L-2) was isolated from persistently HIV-1-infected MT-4 cells. The syncytium-forming capacity of the cell and virus particle fractions was examined in human CD4-positive T cells. Several cell lines producing infectious HIV-1 particles, such as persistently HIV-1-infected MOLT-4 (MOLT-4/HIV-1) cells, were used as controls. Syncytia were formed within 20 h by the cell fraction of both L-2 and MOLT-4/HIV-1 and the virus particle fraction of L-2, but not MOLT-4/HIV-1. These formations were not affected by 3'-azido-3'-deoxythymidine (ZDV). In contrast, similar syncytium formation was first observed 2 days after the incubation of the virus particle fraction of MOLT-4/LAV-1 and this syncytium formation mediated by the cell fractions of MOLT-4/HIV-1 and L-2 or the virus particle fraction of L-2 differently.
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PMID:Noninfectious doughnut-shaped human immunodeficiency virus type 1 can induce syncytia mediated by fusion of the particles with CD4-positive cells. 168 74

Human immunodeficiency virus type-1 (HIV-1) and human T-cell leukemia virus type-I (HTLV-I) have a similar tropism for target cell types, especially for CD4+ T cells. In this study, we provide evidence that receptors of these two viruses exist independently on the target cell. We established an HTLV-I-producing CD8+ T cell line (ILT-8M2) with a remarkable cell fusion capacity. When cocultured with MOLT-4 cells, ILT-8M2 cells induced giant syncytia more efficiently than any other tested HTLV-I-producer cell lines. In contrast to other HTLV-I-producers, ILT-8M2 cells were minimally susceptible to cytopathic effects of HIV-1 due to very low expression of CD4, although they were able to be persistently infected by HIV-1. The indicator MOLT-4 cells are known to respond well to HIV-1-induced cell fusion, but they lose this ability if they become persistently infected with HIV-1 because of the reduction of CD4 receptor expression. ILT-8M2 was, however, still capable of inducing syncytia with the MOLT-4 cells persistently infected by HIV-1 (MOLT-4/IIIB). This syncytium formation was dependent on the HTLV-I-envelope, as it was inhibited by HTLV-I-positive human sera or a monoclonal antibody to HTLV-I gp46 but not by monoclonal antibodies to HIV-1 gp120 or CD4. Moreover, ILT-8M2 cells persistently infected by HIV-1 (ILT-8M2/IIIB) induced both HTLV-I- and HIV-1-mediated syncytia with uninfected MOLT-4 cells. These results suggest that HTLV-I induces cell fusion utilizing receptors on the target cells independent of HIV-1-receptors.
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PMID:Coexistence of fusion receptors for human T-cell leukemia virus type-I (HTLV-I) and human immunodeficiency virus type-1 (HIV-1) on MOLT-4 cells. 168 90

Tumor necrosis factor alpha (TNF-alpha) completely reverses the activity of azidothymidine (AZT) against human immunodeficiency virus type 1 (HIV-1) in MOLT-4 cell cultures. The 50% effective concentration of AZT, required to protect MOLT-4 cells against the cytopathic effect of HIV-1, increased from 5.8 nM in the absence of TNF-alpha to greater than 125 microM in the presence of TNF-alpha (100 U/ml). TNF-alpha also antagonized the anti-HIV-1 activity of dideoxycytidine but did not markedly affect the anti-HIV-1 activity of dextran sulfate. The intracellular phosphorylation pattern of AZT was not changed upon the presence of TNF-alpha.
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PMID:Tumor necrosis factor antagonizes inhibitory effect of azidothymidine on human immunodeficiency virus (HIV) replication in vitro. 168 69

Multinucleated giant cell (syncytium) formation induced by the interaction between the gp120 glycoprotein expressed on the surface of cells infected with human immunodeficiency virus type (HIV-1) and the CD4 receptor of uninfected CD4-positive (CD4+) cells may play an important role in the depletion of T4 lymphocytes in acquired immune deficiency syndrome (AIDS) patients. Using a double fluorescence cell-staining technique and analysis of the cells by the fluorescence-activated cell sorter (FACS), we have demonstrated that giant cell formation between persistently HIV-1-infected HUT-78 cells and uninfected MOLT-4 cells results in a selective destruction of the uninfected CD4+ MOLT-4 cells. Apparently, bystander CD4+ cells may serve as targets for the killing effect of the HIV-1-infected cells, and this killing effect is preceded by fusion between the target (uninfected) and aggressor (infected) cells. Pentosan polysulfate, dextran sulfate, and various other sulfated polysaccharides, but not heparin, have proved to inhibit this cell fusion process and hence protect the target CD4+ cells against destruction by the killer HIV-1-infected cells. Azidothymidine does not interfere with this process. Assuming that fusion between HIV-infected and uninfected CD4+ cells is a crucial event in the pathogenesis of AIDs, any compounds that specifically interfere with this process may be therapeutically advantageous in the treatment of this disease.
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PMID:Sulfated polysaccharides as potent inhibitors of HIV-induced syncytium formation: a new strategy towards AIDS chemotherapy. 169 Dec 88


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