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)

Eleven murine hybridoma clones were selected for their ability to produce anti-HIV-1 integrase (IN) antibodies. Competition and epitope mapping studies allowed segregation of the monoclonal antibodies (MAbs) into four distinct classes. The five MAbs that comprise the first class showed high affinity for epitopes within an N-terminal domain of 58 amino acids that includes a conserved zinc finger motif. The second class, with two MAbs, showed high affinity for epitopes within 29 amino acids at the C terminus. Another two MAbs, which constitute the third class, displayed moderate affinities for epitopes that mapped to regions within the highly conserved catalytic core referred to as the D,D(35)E domain. One of these MAbs showed significant cross-reactivity with HIV-2 IN and weak, but detectable, cross-reactivity with RSV IN. The remaining two MAbs, which comprise the fourth class, exhibited fairly low binding affinities and appeared to recognize epitopes in the zinc finger motif domain as well as the C-terminal half of the IN protein. The MAbs can be used for immunoprecipitation and immunoblotting procedures as well as for purification of HIV-1 IN protein by affinity chromatography. We show that several can also be used to immunostain viral IN sequences in HIV-1-infected T cells, presumably as a component of Gag-Pol precursors. Finally, analysis of our mapping and competition data suggests a structure for mature IN in which the C terminus approaches the central core domain, and the N and C termini touch or are proximal to each other. These MAbs should prove useful for further analyses of the structure and function of IN both in vitro and in vivo.
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PMID:Monoclonal antibodies against HIV type 1 integrase: clues to molecular structure. 753 24

HIV-1 reverse transcriptase (RT) was found to increase the activity of HIV-1 proteinase in vitro and in eukaryotic cells. The effect of RT on proteinase activity was dose-dependent and independent of pH or salt concentration. The cleavage of sequences corresponding to all the naturally occurring cleavage sites that could be tested in vitro was enhanced. The effect of RT on cleavage was greatest at the cleavage site between RT and integrase. The enhancement of viral proteinase activity by the virus RT may contribute to regulation of the order and/or efficiency of cleavage at different sites during virus replication and maturation.
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PMID:Enhancement of HIV-1 proteinase activity by HIV-1 reverse transcriptase. 753 Mar 93

The integration of a DNA copy of the human immunodeficiency virus type 1 (HIV-1) genome into a chromosome of an infected cell is a pivotal step in virus replication. Integration requires the activity of the virus-encoded integrase, which enters the cell as a component of the virion. Results of numerous mutagenesis studies have identified amino acid residues and protein domains of HIV-1 integrase critical for in vitro activity, but only a few of these mutants have been studied for their effects on HIV replication. We have introduced site-directed changes into an infectious DNA clone of HIV-1 and show that integrase mutations can affect virus replication at a variety of steps. We identified mutations that altered virion morphology, levels of particle-associated integrase and reverse transcriptase, and viral DNA synthesis. One replication-defective mutant virus which had normal morphology and protein composition displayed increased levels of circular viral DNA following infection of a T-cell line. This virus also had a significant titer in a CD4-positive indicator cell assay, which requires the viral Tat protein. Although unintegrated viral DNA can serve as a template for Tat expression in infected indicator cells, this level of expression is insufficient to support a spreading viral infection in CD4-positive lymphocytes.
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PMID:Multiple effects of mutations in human immunodeficiency virus type 1 integrase on viral replication. 753 63

Five anti-subtype O specimens were tested by anti-HIV-1/2 screening and confirmatory assays. They can be divided into three specimens, reactive with all ELISAs, independent of the nature of the antigen (recombinant proteins or peptides) and test configuration (indirect ELISA or double antigen/sandwich ELISA). One specimen was not detected by one peptide based ELISA. One specimen was only recognized by two ELISAs and should be considered as a marker sample for the weakness of currently used ELISAs with anti-subtype O. Three different immunoblot assays available commercially detected two of the specimens with a major binding of gp160 and other viral bands, especially the integrase and reverse transcriptase. Another two specimens lacked reactivity with glycoproteins almost completely, but showed some staining with the enzymes of HIV, and would most probably be interpreted as indeterminate. The fifth specimen, which was also missed by most of the ELISAs, had very faint staining of the gp160 and a very weak staining of p24, and would most probably be interpreted as negative. Adaption of currently available tests to anti-subtype O is needed for the future reliability of anti-HIV diagnostic reagents.
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PMID:Reactivity of five anti-HIV-1 subtype O specimens with six different anti-HIV screening ELISAs and three immunoblots. 753 51

The human immunodeficiency virus type-1 (HIV-1) integrase protein (IN) mediates the insertion of linear double-stranded viral DNA into the host genome. Mutations in IN can have different effects on the virus life cycle. In this study, Gag-Pol polyprotein processing, Tat synthesis, and viral replication were investigated in integrase-defective HIV-1 mutants. In the absence of IN synthesis, the Gag-Pol polyprotein stability, packaging, and/or processing was reduced. There was limited expression of Tat observed in IN mutants, but no viral replication.
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PMID:Analysis of human immunodeficiency virus type 1 integrase mutants. 749 94

The course of drug development for the treatment of HIV-1 infection and AIDS is being revolutionized by high-resolution structures of essential viral proteins. We survey the impact on drug design of the recently elucidated structural knowledge of two essential enzymes, reverse transcriptase and protease, and three new targets, the viral integrase and the gene regulatory protein-RNA interactions, Tat-TAR and Rev-RRE.
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PMID:Progress in anti-HIV structure-based drug design. 754 68

We have determined the solution structure of the DNA-binding domain of HIV-1 integrase by nuclear magnetic resonance spectroscopy. In solution, this carboxyterminal region of integrase forms a homodimer, consisting of two structures that closely resemble Src-homology 3 (SH3) domains. Lys 264, previously identified by mutagenesis studies to be important for DNA binding of the integrase, as well as several adjacent basic amino acids are solvent exposed. The identification of an SH3-like domain in integrase provides a new potential target for drug design.
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PMID:The DNA-binding domain of HIV-1 integrase has an SH3-like fold. 755 53

Retroviral integrase (IN) functions to insert retroviral DNA into the host cell chromosome in a highly coordinated manner. IN catalyzes two biochemically separable reactions: processing of the viral DNA ends and joining of these ends to the host DNA. Previous studies suggested that these two reactions are chemically similar and are carried out by a single active site that is characterized by a highly conserved constellation of carboxylate residues, the D,D(35)E motif. We report here the crystal structure of the isolated catalytic domain of avian sarcoma virus (ASV) IN, solved using multiwavelength anomalous diffraction data for a selenomethionine derivative and refined at 1.7 A resolution. The protein is a crystallographic dimer with each monomer featuring a five-stranded mixed beta-sheet region surrounded by five alpha-helices. Based on the general fold and the arrangement of catalytic carboxylate residues, it is apparent that ASV IN is a member of a superfamily of proteins that also includes two types of nucleases, RuvC and RNase H. The general fold and the dimer interface are similar to those of the analogous domain of HIV-1 IN, whose crystal structure has been determined at 2.5 A resolution. However, the ASV IN structure is more complete in that all three critical carboxylic acids, Asp64, Asp121 and Glu157, are ordered. The ordered active site and the considerably higher resolution of the present structure are all important to an understanding of the mechanism of retroviral DNA integration, as well as for designing antiviral agents that may be effective against HIV.
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PMID:High-resolution structure of the catalytic domain of avian sarcoma virus integrase. 756 93

MAP30 (Momordica anti-HIV protein of 30 kDa) and GAP31 (Gelonium anti-HIV protein of 31 kDa) are anti-HIV plant proteins that we have identified, purified, and cloned from the medicinal plants Momordica charantia and Gelonium multiflorum. These antiviral agents are capable of inhibiting infection of HIV type 1 (HIV-1) in T lymphocytes and monocytes as well as replication of the virus in already-infected cells. They are not toxic to normal uninfected cells because they are unable to enter healthy cells. MAP30 and GAP31 also possess an N-glycosidase activity on 28S ribosomal RNA and a topological activity on plasmid and viral DNAs including HIV-1 long terminal repeats (LTRs). LTRs are essential sites for integration of viral DNA into the host genome by viral integrase. We therefore investigated the effect of MAP30 and GAP31 on HIV-1 integrase. We report that both of these antiviral agents exhibit dose-dependent inhibition of HIV-1 integrase. Inhibition was observed in all of the three specific reactions catalyzed by the integrase, namely, 3' processing (specific cleavage of the dinucleotide GT from the viral substrate), strand transfer (integration), and "disintegration" (the reversal of strand transfer). Inhibition was studied by using oligonucleotide substrates with sequences corresponding to the U3 and U5 regions of HIV LTR. In the presence of 20 ng of viral substrate, 50 ng of target substrate, and 4 microM integrase, total inhibition was achieved at equimolar concentrations of the integrase and the antiviral proteins, with EC50 values of about 1 microM. Integration of viral DNA into the host chromosome is a vital step in the replicative cycle of retroviruses, including the AIDS virus. The inhibition of HIV-1 integrase by MAP30 and GAP31 suggests that impediment of viral DNA integration may play a key role in the anti-HIV activity of these plant proteins.
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PMID:Inhibition of the integrase of human immunodeficiency virus (HIV) type 1 by anti-HIV plant proteins MAP30 and GAP31. 756 24

Retroviruses require viral DNA to be synthesized by reverse transcription in the cytoplasm followed by integration of the resulting viral DNA into the host chromosome in the nucleus. Reverse transcription and integration, essential steps in the life cycle of retroviruses, are possible targets in the development of antiviral reagents. One attractive target is the integrase protein, a product of the retroviral pol gene which is solely responsible for the retroviral integration process through cutting and joining reactions. When screening for massive numbers of antiviral agents, a rapid and precise assay is ideal. We report the application of fluorescence resonance energy transfer (FRET) with fluorescein and eosin as the energy transfer pair to characterize HIV-IN-mediated DNA cleavage reactions. Past concerns with applications of FRET to DNA were due to interactions of the fluorophore with the DNA, resulting in quenched fluorescence. However, in this study these concerns have been resolved with the use of a nucleotide analog with a 12-carbon linker arm, 5-amino (12)-2'-deoxyuridine beta-cyanoethyl phosphoramidite. Steady-state fluorescence studies show that cleavage of the fluorogenic substrate by integrase results in enhancement of quenched donor fluorescence intensity. The fluorescence assay was confirmed by autoradiographic analysis of the cleavage reaction with radiolabeled fluorogenic substrate. This fluorescence assay will facilitate both detailed kinetic studies and the rapid screening of novel integrase inhibitors.
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PMID:Characterization of endonucleolytic activity of HIV-1 integrase using a fluorogenic substrate. 757 50


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