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

Monoclonal antibodies have been isolated from human immunodeficiency virus type 1 (HIV-1)-infected patients that recognize discontinuous epitopes on the gp120 envelope glycoprotein, that block gp120 interaction with the CD4 receptor, and that neutralize a variety of HIV-1 isolates. Using a panel of HIV-1 gp120 mutants, we identified amino acids important for precipitation of the gp120 glycoprotein by three different monoclonal antibodies with these properties. These amino acids are located within seven discontinuous, conserved regions of the gp120 glycoprotein, four of which overlap those regions previously shown to be important for CD4 recognition. The pattern of sensitivity to amino acid change in these seven regions differed for each antibody and also differed from that of the CD4 glycoprotein. These results indicate that the CD4 receptor and this group of broadly neutralizing antibodies recognize distinct but overlapping gp120 determinants.
J Virol 1992 Sep
PMID:Discontinuous, conserved neutralization epitopes overlapping the CD4-binding region of human immunodeficiency virus type 1 gp120 envelope glycoprotein. 138 99

HIV use the CD4 molecule as their primary cellular receptor. Residues in the N-terminal domain (D1) of CD4 are crucial to HIV attachment through the gp120 envelope component. However, other regions of CD4 appear to be required subsequently for virus- and cell-cell fusion. Little is understood of the post-binding steps which may differ between HIV variants. We report a novel anti-CD4 mAb that does not block CD4/gp120 binding, but that does efficiently block both viral infection and cell-cell syncytia formation, and define its contact site as residues in CD4 D2 using both mouse/human CD4 chimeras and CD4 substitution mutants. We also investigated the basis for its antiviral effect. Using the CD4 D2 specific mAb, we identify another conserved step in HIV infection, as evidenced by its ability to neutralize a broad range of primary isolates and T cell-line passaged strains. Monovalent forms of the mAb were used to determine if its activity was due to masking of the D2 epitope, to steric inhibition, or bivalency. Our data indicate that both binding site and bivalency of the mAb underlie its potency. The need for bivalency is not simply explained by affinity, because monovalent forms can displace the intact mAb and reverse its protective effect. These results provide evidence that binding of the D2-specific mAb prevents structural alterations necessary for membrane fusion.
J Immunol 1992 Sep 01
PMID:Inhibition of HIV infection by a novel CD4 domain 2-specific monoclonal antibody. Dissecting the basis for its inhibitory effect on HIV-induced cell fusion. 138 May 39

The role of natural killer (NK) cells and their inducible counterparts, lymphokine-activated killer (LAK) cells in AIDS with regard to HIV-1 viral immunosurveillance and the control of secondary opportunistic disease has yet to be established. In this study, we have demonstrated that LAK cells derived from all HIV-1+ groups showed striking increases in their capacity to lyse HIV-1-infected U-937 cells relative to their uninfected U-937 counterparts. Surprisingly, similarly derived LAK cells from healthy seronegative controls showed no differences in their lysis of HIV-1-infected versus uninfected U-937 cells. The differential ability of LAK effectors from seropositive donors to lyse HIV-1-infected targets was demonstrable using a number of U-937 subclones and their HIV-1-infected counterparts. Again, no differences in LAK cell-mediated lysis of HIV-1-infected and uninfected U-937 subclones were observed in seronegative individuals. Our findings that HIV-1+ individuals show selective expansion of non-MHC restricted, HIV-1-directed cytotoxic LAK cells indicate that natural immunity may indeed play a role in HIV-1 viral immunosurveillance.
Clin Exp Immunol 1992 Sep
PMID:Increased LAK activity against HIV-infected cell lines in HIV-1+ individuals. 138 Dec 98

Several novel, structurally distinct classes of specific human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) nonnucleoside inhibitors have been described recently. These include the pyridinone derivatives L-697,639, L-697,661, and L-696,229 as well as BI-RG-587 and the tetrahydroimidazo[4,5,1-j,k]-benzodiazepin-2(1H)-one and -thione compounds. Previous studies have implicated involvement of the RT amino acid residues at positions 103, 181, and 188 in the activity of the compounds. Accordingly, HIV-1 RT mutants containing a series of amino acid substitutions at these positions were constructed. The relative resistance of purified mutant enzymes to each of the inhibitors was assessed. This analysis established the functional equivalence of the three inhibitor classes and provided evidence for the interaction of the 103 site with the 181/188 region. Amino acid substitutions at these positions were also found to influence RT sensitivity to inhibition by phosphonoformate, thereby suggesting a close association between this pyrophosphate analog's binding site in RT and the binding site of the nonnucleoside inhibitors. In addition, aromatic stacking of the amino acid side groups at residues 181 and 188 was suggested to be required for inhibitor activity.
J Biol Chem 1992 Sep 05
PMID:Functional analysis of HIV-1 reverse transcriptase amino acids involved in resistance to multiple nonnucleoside inhibitors. 138 50

Antilymphocyte antibodies, including autoantibodies to CD4, have been reported in AIDS patients and are postulated to contribute to T cell depletion and immunologic dysfunction. In this paper, we characterize and localize binding sites of human anti-CD4 autoantibodies from a number of HIV+ patients. Epitope mapping by ELISA and Western blotting, together with cross-competition experiments, showed that common autoepitopes were localized to at least two topographically separate sites on the fourth domain of sCD4. These sites were partially dependent on the carboxyl terminus of the soluble molecule and were not exposed on full length membrane CD4, even under denaturing Western blotting conditions. Peptide screening identified peptides from the fourth and third domains that were recognized by several, but not all, anti-CD4 serum samples. Soluble CD4 affinity-purified antibodies were predominantly IgG1 and were not induced to bind mCD4 after gp120 binding to T cells. Analysis of HIV seroconversion panels showed that the appearance of anti-CD4 antibodies followed HIV seroconversion by 6 to 12 months and paralleled anti-gp120 reactivity. This suggested a correlation between immune reactivity to envelope and anti-CD4 antibody production. Together, the data indicate that human anti-CD4 antibodies recognize cryptic conformational and linear epitopes on a cleaved form of CD4. These findings suggest that HIV may induce abnormal cleavage of full length CD4, thereby exposing immunogenic self epitopes normally hidden from humoral and cellular immune interactions. This model of abnormal processing of self Ag has general implications for autoantigen exposure in other autoimmune disorders.
J Immunol 1992 Sep 15
PMID:Analysis of HIV-induced autoantibodies to cryptic epitopes on human CD4. 138 99

The effects of the immunosuppressive drugs cyclosporin A and FK 506 were studied on cells chronically infected with human immunodeficiency virus type 1 (HIV-1) as well as on uninfected and newly infected cells. When cells chronically infected with HIV-1 or with HIV-2 were cocultivated with uninfected cells in the presence of cyclosporin A or FK 506 there was a delay in the formation of syncytia and of cytopathic effects. This inhibitory effect was not due to decreased membrane expression of CD4. In addition, there was an approximately 100-fold reduction in the yield of infectious HIV-1 when the infected cells were grown in the presence of these drugs, a finding consistent with other evidence of decreased HIV expression. Both drugs were found to inhibit the growth of chronically infected cells at concentrations that did not inhibit the growth of the uninfected cells. These results, demonstrating that cyclosporin A and FK 506 interfere with HIV production and selectively inhibit the growth of infected cells, suggest that they may be useful in the treatment of this infection and indicate further cellular targets for antiviral agents.
Proc Natl Acad Sci U S A 1992 Sep 01
PMID:Inhibition of human immunodeficiency virus and growth of infected T cells by the immunosuppressive drugs cyclosporin A and FK 506. 138 9

The majority of infants born to HIV-positive mothers are not infected in utero, suggesting that the pregnancy factors produced by fetal trophoblasts may provide protection against HIV-1 infection. Except for steroid female hormones, little is known of other pregnancy factors that may regulate either resistance or susceptibility to HIV-1. Human chorionic gonadotropin (hCG)--the major glycoprotein produced by the placental trophoblast throughout the pregnancy--was tested on reverse transcriptase activity in HIV-infected ACH-2 lymphocytes and U1 monocytes. The results suggest that low non-cytotoxic doses of hCG (0.01-1.0 IU range) may inhibit viral replication in maternal blood cells.
FEMS Microbiol Lett 1992 Sep 01
PMID:Effect of human chorionic gonadotropin (hCG) on reverse transcriptase activity in HIV-1 infected lymphocytes and monocytes. 138 34

We have generated by site-directed mutagenesis plasmids that induce the synthesis of specific mutants of the reverse transcriptase (RT) of human immunodeficiency virus type 1 (HIV-1). These recombinant mutants of HIV-1 RT, designed on the basis of our previous studies of HIV-1 and HIV-2 RTs, were analyzed for structure-function relationship by assessing their RNA-dependent and DNA-dependent DNA polymerase as well as the ribonuclease H activities. Three groups of mutants were studied. 1) We have investigated the importance of the only two sets of highly conserved double prolines found in the sequence of HIV-1 RT. The results indicate that the conversion of either one or both prolines (at positions 225 and 226) to threonines have no significant effect on all catalytic activities of the enzyme. The mutants in which prolines 419 and 420 were individually modified to threonines exhibit full activities, whereas the double proline 419/420 mutant lost most of its RNase H activity (although the DNA polymerase function was fully retained). 2) We have deleted phenylalanine 346 from HIV-1 RT, which is absent in wild type HIV-2 RT. This mutant of HIV-1 RT lost practically all catalytic activities. 3) A mutant of HIV-1 RT in which a cysteine residue substituted for alanine 446, was found to be slightly hyperactive for both DNA polymerase and RNase H activities.
J Biol Chem 1992 Sep 15
PMID:Functional analysis of novel selective mutants of the reverse transcriptase of human immunodeficiency virus type 1. 138 52

The precursor homodimeric p66/p66 form of human immunodeficiency virus type-1 reverse transcriptase (HIV-1 RT) possesses the DNA polymerase and RNase H activities involved in the synthesis of the double-stranded provirus DNA. Reverse transcription is initiated from tRNALys in the case of HIV-1. The present study confirmed that interactions between HIV-1 RT and tRNALys induce protein conformational changes and demonstrated that these interactions stimulate the enzymatic activities associated with the p66 subunit. Thus, the p66/p66 form of the enzyme is strongly stimulated in both DNA polymerase and RNase H activities. Preincubation of the enzyme with tRNA is an obligatory step to obtain the stimulatory effect. The affinity of template, primer, or substrate for RT p66/p66 did not change when the enzyme was preincubated with tRNALys at stimulatory concentrations; the interaction of tRNA with p66/p66 has an effect only on the maximal rate of polymerization. It is further shown that the RNase H domain of RT is much more accessible to protease attack than the DNA polymerase active site.
J Biol Chem 1992 Sep 25
PMID:Interaction of tRNALys with the p66/p66 form of HIV-1 reverse transcriptase stimulates DNA polymerase and ribonuclease H activities. 138 72

We have characterized the discontinuous epitopes recognized by two rat and three human neutralizing monoclonal antibodies (mAb) by examining the effect of single amino acid changes in conserved residues of gp120 on mAb recognition. A human mAb derived from an infected individual, 448D, and two rat mAbs, 39.13g and 39.3b, respectively, derived by immunization with native recombinant gp120, recognize similar epitopes. Recognition of the envelope glycoproteins by these mAbs was affected by changes in gp120 amino acid residues 88, 113, 117, 257, 368, or 370. The gp120 amino acids 257, 368, and 370 have previously been reported to be important for CD4 binding, which is consistent with the ability of these mAbs to block the gp120-CD4 interaction. Residues 88, 113, and 117 are not thought to be important for CD4 binding, suggesting that the antibody epitopes overlap, but are distinct from, the CD4 binding region. We also found that some alterations in gp120 residues 88, 117, 368, or 421 reduced the ability of polyclonal sera from HIV-1-infected individuals to inhibit the interaction of the mutant gp120 glycoproteins with soluble CD4. Thus, changes in the HIV-1 gp120 glycoprotein that minimally affect the receptor binding may allow escape from neutralizing antibodies directed against the CD4 binding region.
Virology 1992 Sep
PMID:Amino acid residues of the human immunodeficiency virus type I gp120 critical for the binding of rat and human neutralizing antibodies that block the gp120-sCD4 interaction. 138 39


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