Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Increased levels of inflammatory cytokines, including tumor necrosis factor (TNF), interleukin-1 (IL-1), and IL-6, have been detected in specimens from human immunodeficiency virus type 1 (HIV-1)-infected individuals. Here we demonstrate that HIV-1 activates the expression of TNF but not of IL-1 and IL-6 in acutely and chronically infected T cells. The increase in TNF gene expression is due to activation of the TNF promoter by the viral gene product Tat. Transactivation of TNF gene expression requires the product of the first exon of the tat gene and is cell type independent. T cells chronically infected with pol-defective HIV-1 provirus constitutively express both Tat and TNF at levels significantly higher (fivefold) than those seen in control cells, and treatment with phorbol myristate acetate greatly enhances Tat expression and TNF production. As TNF can increase the production of IL-1 and IL-6 and these inflammatory cytokines all enhance HIV-1 gene expression and affect the immune, vascular, and central nervous systems, the activation of TNF by Tat may be part of a complex pathway in which HIV-1 uses viral products and host factors to increase its own expression and infectivity and to induce disease.
J Virol 1992 Dec
PMID:Effects of the human immunodeficiency virus type 1 Tat protein on the expression of inflammatory cytokines. 127 99

Using BspMI cassette vectors, we have constructed a series of mutations in human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) that cause specific amino acid substitutions within the polymerase domain. The RNA-dependent DNA polymerase, DNA-dependent DNA polymerase, and RNase H activities of the mutant RTs were assayed. The elucidation of the structure of HIV-1 RT makes it possible to determine the locations of specific mutations in the three-dimensional structure of HIV-1 RT [E. Arnold, A. Jacobo-Molina, R. G. Nanni, R. L. Williams, X. Lu, J. Ding, A. D. Clark, Jr., A. Zhang, A. L. Ferris, P. Clark, A. Hizi, and S. H. Hughes, Nature (London) 357:85-89, 1992; L. A. Kohlstaedt, J. Wang, J. M. Friedman, P. A. Rice, and T. A. Steitz, Science 256:1783-1790, 1992]. The mutations described in this report are between amino acids 25 and 81, within the "fingers" domain of RT (Kohlstaedt et al., Science 256:1783-1790, 1992). It has been suggested that this domain may play a role in positioning the template. Although the fingers domain does not contain the active site for polymerization, several of the mutations within this domain disrupt polymerase activity without significantly affecting RNase H activity.
J Virol 1992 Dec
PMID:Mutational analysis of the fingers domain of human immunodeficiency virus type 1 reverse transcriptase. 127 5

We demonstrate that soluble CD4 (sCD4) or a monoclonal antibody (mAb), 39.13g, binding to a conformational epitope of gp120 involved in CD4 binding, and mAbs binding to the V3 domain of gp120, can synergistically neutralize human immunodeficiency virus type I (HIV-1). In contrast, a neutralizing mAb binding to a linear epitope within the CD4 binding domain was unable to exert a synergistic effect in combination with V3 mAbs, suggesting that synergism is dependent on ligands binding to the critical, discontinuous, gp120 residues constituting the CD4 binding site. A number of V3 mAbs showed increased binding to virion gp120 in the presence of sCD4, suggesting a mechanism for the synergistic neutralization. This effect was not observed with recombinant or detergent solubilized viral gp120, suggesting that the oligomeric structure of gp120 on viral particles affects V3 epitope exposure. This hypothesis is supported by the ability of two new V3 mAbs, 8/38c and 8/64b, to only neutralize HIV-1 in the presence of sCD4 or mAb 39.13g; binding studies demonstrate that these mAbs only bind to virion gp120 in the presence of sCD4. Thus, V3 epitope exposure is modulated by the interaction of virion gp120 with ligands specific for the CD4 binding domain and results in enhanced antibody-mediated neutralization.
Virology 1992 Dec
PMID:Synergistic interaction between ligands binding to the CD4 binding site and V3 domain of human immunodeficiency virus type I gp120. 128 Mar 82

The cytopathic effects of HIV-1 produced by direct infection of human T cells do not account for the disproportionate loss of CD4-positive lymphocytes during the course of HIV infection. Previous studies have demonstrated the inhibition of uninfected human T cell activation and proliferation by the HIV-1 envelope glycoproteins, presumably due to gp120-CD4 interactions. To examine the ability of HIV-1 to inhibit T cell proliferation in the absence of both direct infection and gp120-CD4 interactions, we tested the effect of HIV-1 on mouse T cell proliferation. Culture media containing HIV-1 released from infected cells inhibited T lymphocyte proliferation in response to interleukin-2 (IL-2). Studies to explore the mechanism of this inhibition suggested that the decrease in proliferation resulted from interactions between HIV-1 and the mouse cells, but did not involve IL-2/IL-2 receptor interactions. We used monoclonal antibodies to demonstrate that the HIV-1 envelope glycoproteins were required for the inhibition of murine T cell proliferation. Anti-gp120 antibodies completely restored proliferation, indicating that the surface protein gp120 was primarily required for the inhibition of proliferation. However, antibodies directed against the transmembrane protein of HIV-1 (gp41) also partially restored lymphocyte proliferation. The functional significance of the HIV-1 envelope protein epitopes recognized by the monoclonal antibodies is discussed.
Virology 1992 Dec
PMID:CD4-independent inhibition of lymphocyte proliferation mediated by HIV-1 envelope glycoproteins. 128 Mar 85

We performed a retrospective analysis of longitudinal clinical and immunologic data obtained from 22 children in the early stages of infection with human immunodeficiency virus (HIV) when they developed varicella. We studied the course of HIV infection to determine whether clinical deterioration occurred after chickenpox. We examined the following indices: growth and development; neurologic status; helper T lymphocyte counts; blood values of core (p24) antigen of HIV; changes in the stage of HIV infection; and need for administration of zidovudine. We studied children for a mean of 2.8 years and for as long as 9.8 years after onset of varicella. There was little evidence that chickenpox affected HIV infection. Three (14%) children developed clinical zoster, 2 of whom (9%) had evidence of chronic infection with varicella-zoster virus. One additional child (5%) had 2 episodes of chickenpox. These observations suggest that children with early HIV infection could be considered for immunization with live attenuated varicella vaccine, which would be predicted to decrease their morbidity from varicella-zoster virus.
Pediatr Infect Dis J 1992 Dec
PMID:Varicella does not appear to be a cofactor for human immunodeficiency virus infection in children. 128 8

Opsonization of the HTLV-RF and HTLV-IIIB strains of HIV-1 with normal human HIV seronegative serum under conditions that allow complement activation resulted in the productive infection of cells of the Raji B lymphoblastoid cell line. Under the same experimental conditions, no infection of Raji cells was observed with unopsonized virus. Infection of Raji cells with complement-opsonized HIV-1 was totally suppressed by preblocking the function of CR2 (the C3dg receptor, CD21) on the cells with a monoclonal anti-CR2 antibody cross-linked with rabbit F(ab')2 anti-mouse immunoglobulin antibodies. Infection of Raji cells occurred independently of CD4 since the cells lacked the expression of CD4 antigen and of CD4 transcripts. Thus, Raji cells may be infected with complement-opsonized HIV independently of CD4 and in the absence of antibodies. By mediating and/or enhancing HIV infection, complement and complement receptors contribute to extend the range of target cells to the virus and may increase infection in patients with a low viral load.
Scand J Immunol 1992 Dec
PMID:Complement receptor type 2 mediates infection of the human CD4-negative Raji B-cell line with opsonized HIV. 128 36

We demonstrate in vitro the occurrence of a specific but low-affinity interaction between soluble tetrameric rgp160 or soluble monomeric or tetrameric rgp120 and heparin-agarose (HA). This interaction is saturable, pH and temperature-dependent, and can be inhibited by soluble heparin, but not by soluble dextran. In buffer supplemented with 10 mM CaCl2, the C50 of soluble heparin, i.e., the concentration of soluble heparin which leads to 50% inhibition of the binding of [125I]rgp160 or of [125I]rgp120 to HA, is 1.1 x 10(-4) disaccharidic molar concentration for rgp160 and 3.2 x 10(-4) dissacharidic molar concentration for rgp120, which indicates low-affinity interactions. Upon chromatography on HA, [125I]rgp160 is repeatedly eluted as a retarded fraction when compared to the elution volume of [125I]rgp160-soluble heparin complex. Under the same experimental conditions, [125I]rgp120 is also eluted, but as a less retarded fraction than [125I]rgp160. Taken together, these results suggest that, at least part of the described anti HIV-1 activity of heparin might be mediated by interaction with HIV-1 major envelope glycoprotein.
Biochim Biophys Acta 1992 Dec 10
PMID:The interaction of a glycosaminoglycan, heparin, with HIV-1 major envelope glycoprotein. 128 30

Maleylated-human serum albumin (Mal-HSA) inhibited human immunodeficiency virus type-1 (HIV-1) infection of MT-4 cells in vitro. It was also found to inhibit the fusion between uninfected CD4+ cells (Molt-4 clone 8 cells) and HIV-1 infected cells (Molt-4/HIV-1) to form syncytia. To investigate the mechanism of the inhibition, a study was designed to determine whether Mal-HSA could bind to CD4+ cells. Mal-HSA could bind to both MT-4 cells and Molt-4 clone 8 cells with high affinity, Kd = 2.0 nM and Kd = 5.8 nM, respectively. However, Mal-HSA could neither inhibit anti CD4 antibody Leu 3a binding to Molt-4 clone 8 cells nor modulate the expression of CD4 molecules on the surface of the cells. Mal-HSA binding to Molt-4 clone 8 cells was completely inhibited by sulfated polysaccharides bearing anti-HIV activity, such as dextran sulfate, fucoidan and carrageenan. Other HIV-1 susceptible human T-cell lines, such as Molt-4, CEM-5, H-9 and HuT-78 cells, also have Mal-HSA binding sites showing a high affinity, Kd = 0.9 +/- 0.4 nM. Mal-HSA binding proteins of Molt-4 clone 8 cells were identified by ligand blotting as 155 and 220 kDa proteins. Unlike dextran sulfate, Mal-HSA could not inhibit reverse transcriptase activity of HIV-1. These results indicate that Mal-HSA inhibits HIV-1 infection and syncytia formation, and suggest that 155 and/or 220 kDa proteins of target cells are involved in HIV-1 adsorption and/or the membrane fusion between HIV-1 and target cells.
Biochim Biophys Acta 1992 Dec 10
PMID:Maleylated human serum albumin inhibits HIV-1 infection in vitro. 128 31

The sensitivity and specificity of the inhibition of HIV-1 reverse transcriptase by various catechins have been examined. As previously reported, (-)epicatechin 3-gallate inhibits the viral polymerase. However, it is noted here that this inhibition is not observed in the presence of either serum albumin or Triton X-100. Other catechins behave similarly to (-)epicatechin 3-gallate in that they inhibit polymerase activity only in the absence of these reagents. Additionally, other DNA polymerases are inhibited to a similar degree by (-)epicatechin 3-gallate. Taken cumulatively, these results suggest that these catechins, and in particular (-)epicatechin 3-gallate, bind with no apparent selectivity and that the observed inhibition of HIV-1 reverse transcriptase is non-specific in nature.
Biochem J 1992 Dec 15
PMID:Observations on the inhibition of HIV-1 reverse transcriptase by catechins. 128 81

Microglia, brain macrophages, are thought to be the primary target of HIV-1 infection in the brain, because they exclusively express the CD4 antigen which is effectively used for viral entry. The expression of CD4 mRNA in cultured microglia could be detected by the reverse-PCR method. Using this and immunohistochemical staining, we found that the immunosuppressants cyclosporin A and FK506 decreased CD4 expression in cultured murine microglia without causing any significant decrease in cell viability. FK506 was more potent than cyclosporin A. Lipopolysaccharide also decreased CD4 mRNA expression in microglia. The effects of immunosuppressants and lipopolysaccharide seemed to be specific for microglia since these chemicals did not alter the CD4 expression in lymphocytes or peritoneal macrophages. These agents, if modified to pass through the blood-brain barrier, may prevent viral spread of HIV-1 infection in the central nervous system and the AIDS-dementia complex.
Biochem Biophys Res Commun 1992 Dec 15
PMID:Down regulation of CD4 expression in cultured microglia by immunosuppressants and lipopolysaccharide. 128


1 2 3 4 5 6 7 8 9 10 Next >>