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

The author gives a survey of groups of substances which have a marked and selective effect on HI thus serving as potential chemotherapeutical means against AIDS. They can be divided into three groups: 1. anionic substances, 2. 2, 3-dideoxynucleoside analogues and 3. sulphate polysaccharides. The mechanism of the effect of the substances of the 2nd group probably inhibits reverse HIV transcriptase. The substances of the 3rd group are to prevent adsorption of virus particles by the cells. The substances of the 1st group inhibit HIV transcriptase but also interfere with the adsorption process of the virus particles, or with other stages and phases of the HIV replication cycle. The crystallized substances of these groups should be further studied as potential therapeutic agents for the treatment of AIDS and other retrovirus infections (PMEA, D4T, dextran-sulphate, pentosan, polysulphate and others). The survey also includes information on the so-called anti-sense RNA.
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PMID:[Perspectives in AIDS chemotherapy]. 257 16

A quantitative, nonisotopic hybridization assay which measures specific DNA-RNA hybrids is described. A biotinylated RNA probe is reacted in solution with a DNA target and the labeled hybrids are immobilized onto a solid phase surface with an antibiotin antibody. Bound hybrids are detected with a beta-galactosidase-labeled monoclonal antibody against DNA-RNA hybrids and are quantitated with the addition of a fluorogenic substrate. In a model system using pSP65 or pGEM4 plasmids and transcripts, biotinylated RNA probes allowed detection of 5 pg of DNA in 10(6) pg of exogenous nucleic acids in 1000 min. Signals generated in the system depended on input target length. A nucleic acid target of 25 bases was still detectable in the assay. Human immunodeficiency virus type 1 (HIV-1) DNA was amplified in the polymerase chain reaction with Taq polymerase and a set of primers for the pol gene, one of which contained T7 RNA polymerase promoter sequences. A HIV-RNA probe of 326 bases was transcribed with T7 RNA polymerase using polymerase chain reaction (PCR) amplified DNA as a template. The RNA probe of 326 bases performed as well as a RNA probe of 2588 bases for detection of a DNA segment of 355 bp. For detection of dilutions of HIV-1 with PCR, a set of primers (outer set) was used for amplification of HIV-1 DNA. In a separate reaction a set of primers nested between the first set generated through PCR an amplified DNA fragment with the T7 promoter. This fragment was transcribed for the synthesis of a biotinylated RNA probe. This probe could then be reacted with material amplified with the outer set of primers. Ten copies of HIV-DNA could be detected with this procedure.
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PMID:Immunodetection of DNA with biotinylated RNA probes: a study of reactivity of a monoclonal antibody to DNA-RNA hybrids. 178 29

The human immunodeficiency virus (HIV-1) envelope gene was expressed in large-scale microcarrier cultures of Vero cells using a system involving coinfection with two recombinant vaccinia viruses. One recombinant contained the bacteriophage T7 RNA polymerase gene under control of a vaccinia virus promoter. The second contained the HIV-1 gp160 gene flanked by T7 promoter and termination sequences. The protein was expressed on the surface of infected cells, and it was shown to have a molecular weight of 160 kD and to react with gp41 and gp120 specific monoclonal antibodies. After purification by successive affinity and ion-exchange chromatography, the protein was demonstrated to be present in a particulate form with a diameter in the range of 15-30 nm. When injected into goats a high-titer gp160 specific antibody response was elicited and group-specific neutralizing activity could be demonstrated in vitro. The immunogenicity of the protein was also studied in conjunction with a number of adjuvant formulations, and the highest potency in mice was obtained using a preparation with 0.2% Al(OH)3 and 0.25% deoxycholate.
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PMID:Large-scale production and purification of a vaccinia recombinant-derived HIV-1 gp160 and analysis of its immunogenicity. 271 66

The ability of papaverine to inhibit human immunodeficiency virus (HIV) replication in H9 cell line and in peripheral blood mononuclear cell (PBMC) culture was examined. HIV-infected H9 cells were exposed to different concentrations of papaverine for 20 days. Reverse transcriptase (RT) activity and the presence of p24 in the supernatant were determined to assess the level of viral replication in treated and control cultures. The most effective concentration of papaverine in the culture medium was 10 micrograms/ml, a dose that did not significantly affect cell proliferation. At this drug concentration the treatment resulted in no RT activity or p24 expression in the supernatant and no virus antigen detection at the cellular level as demonstrated by Western blot (WB) analysis. The activity of the drug occurred in a short period of time (60 hours) as shown by radioimmunoprecipitation (RIP) assay and affected the synthesis of the env precursor protein gp160. The drug was also effective in inhibiting HIV replication in PBMC cultures and influenced specific viral markers, namely, RT and p24. Evidence of the efficacy of papaverine treatment was enforced by the finding in the treated PBMC cultures, compared with the untreated ones, of a reduced percentage of cells forming syncitia and of the inhibition of the virus-induced decrease in the number of cells. When an equal number of virus-infected H9 cells exposed or unexposed to papaverine was analyzed for HIV-specific proteins, a marked decrease in the expression of the viral proteins was observed in the treated cultures. At the same time, one cellular protein of molecular weight 69,000 was not inhibited by papaverine. This may indicate that, at least for one protein, synthesis may not be affected by the drug. Our data suggest that papaverine merits attention as a possible nontoxic candidate for the treatment of HIV infection.
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PMID:Inhibitory effect of papaverine on HIV replication in vitro. 271 67

Promoter-proximal downstream regions of the human immunodeficiency viruses (HIV-1 and HIV-2) mediate the action of the viral transcription activator protein, Tat. We demonstrate here that the downstream domain of each virus interacts with two RNA polymerase II transcription factors. One of these, CTF/NF I, is a multifunctional protein associated previously with activation of transcription and DNA replication. The other cellular protein, designated LBP-1 (leader-binding protein-1), recognizes repeated elements within an extended region of DNA corresponding to part of the 5'-untranslated leader. Analysis of clustered point mutants in the HIV-1 leader for DNA-binding and transcription activity in vitro and in vivo suggests a role for LBP-1 as part of the basal promoter. A complex overlapping arrangement is observed between sequences required for the interaction of LBP-1 and CTF/NF I proteins and those defined previously for regulation by the HIV-1 Tat protein.
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PMID:Structural arrangements of transcription control domains within the 5'-untranslated leader regions of the HIV-1 and HIV-2 promoters. 284 59

The in vitro amplification of biologically important nucleic acids has proceeded principally by a strategy of DNA replication. Polymerase chain reaction was the first such protocol to achieve this goal. In this report, a transcription-based amplification system (TAS) is described. Each cycle of the TAS is composed of two steps. The first is a cDNA synthesis step that produces one copy of a double-stranded DNA template for each copy of RNA or DNA target nucleic acid. During the course of this cDNA synthesis step, a sequence recognized by a DNA-dependent RNA polymerase is inserted into the cDNA copy of the target sequence to be amplified. The second step is the amplification of the target sequence by the transcription of the cDNA template into multiple copies of RNA. This procedure has been applied to the detection of human immunodeficiency virus type 1 (HIV-1)-infected cells. After four cycles of TAS, the amplification of the vif region of the HIV-1 RNA genome was measured to be, on the average, 38- to 47-fold per cycle, resulting in a 2-5 x 10(6)-fold increase in the copy number of the original target sequence. This amplification by the TAS protocol allows the detection of fewer than one HIV-1-infected CEM cell in a population of 10(6) uninfected CEM cells. Detection of the TAS-generated RNA from HIV-1-infected cells can easily be accomplished by means of a bead-based sandwich hybridization protocol, which provides additional specificity for the identification of the amplified HIV-1-specific sequence.
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PMID:Transcription-based amplification system and detection of amplified human immunodeficiency virus type 1 with a bead-based sandwich hybridization format. 291 66

Human immunodeficiency virus-1 (HIV-1) leader RNA, which contains double-stranded regions due to inverted repeats, was shown to activate the dsRNA-dependent enzymes associated with the interferon system. HIV-1 leader RNA produced in vitro using SP6 RNA polymerase was characterized using probes for antisense and sense-strand RNA. The RNA preparation was free from significant levels of antisense RNA. HIV-1 leader RNA was shown to activate dsRNA-dependent protein kinase in a cell-free system from interferon-treated HeLa cells. Affinity resins, consisting of HIV-1 leader RNA covalently attached to cellulose, immobilized and activated dsRNA-dependent protein kinase and 2-5A-synthetase. HIV-1 leader RNA, therefore, may be a contributing factor in the mechanism by which interferon inhibits HIV replication.
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PMID:Activation of interferon-regulated, dsRNA-dependent enzymes by human immunodeficiency virus-1 leader RNA. 292 80

The long terminal repeat (LTR) of the AIDS virus (HIV) has been found to contain promoter sequences that are active in uninfected HeLa whole cell and nuclear extracts. Here we report that elements upstream of position -104 (start site +1) do not affect transcriptional activity in vitro whereas sequences between -104 and -57 are required for such activity. Using a reconstituted RNA polymerase II system, we demonstrate that a partially purified fraction containing Spl not only stimulates, as was previously reported, but is required for accurate initiation of transcription directed by the HIV LTR. In addition, based on a computerized analysis, we report the presence of a region in the HIV LTR (positions -151 to -80) that is similar to the 72 base pair enhancer element of SV40 and that includes a highly conserved segment also present in the cytomegalovirus enhancer. Moreover, the HIV and HTLV-I LTRs are shown to share a region of similarity that includes the 21 base pair motif found in the enhancers of the human and bovine T-lymphotropic viruses. The R region of the HIV LTR is found to have two extensive regions of dyad symmetry rather than one as was previously reported. The significance of these observations for HIV pathogenesis is discussed.
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PMID:Transcription directed by the HIV long terminal repeat in vitro. 304 54

In this study we have defined the in vitro requirements for transcriptional regulation of the HIV-2 LTR in response to the HIV-1 and HIV-2 Tat proteins and addressed potential mechanisms of Tat function. HIV-2 contains a duplicated TAR RNA stem-loop structure in contrast to the single stem-loop structure found in HIV-1 TAR RNA. We demonstrated that the HIV-2 proximal TAR RNA stem-loop structure was more important for in vitro transcriptional activation by the HIV-1 and HIV-2 Tat proteins than the distal TAR RNA stem-loop though this downstream TAR element itself was able to confer Tat-responsiveness. The role of the two HIV-2 TAR RNA stem-loop bulge sequences was less critical than the loop sequences for in vitro transcriptional activation by Tat. In addition, we demonstrated that replacing the HIV-2 TATA element with that of HIV-1 markedly reduced the overall level of Tat activation. The role of the Tat-1 and Tat-2 proteins on the synthesis of HIV-1 and HIV-2 promoter proximal and promoter distal transcripts was then investigated. In contrast to the HIV-1 promoter, the HIV-2 promoter generated abundant levels of short transcripts in vitro transcription assays likely due to the structure of its duplicated TAR element. Both Tat-1 and Tat-2 increased the level of transcripts extending to the end of the HIV-1 and HIV-2 TAR elements as well as the level of transcripts extending more than 500 nucleotides from the transcription initiation site. However, the synthesis of transcripts within 30 nucleotides of the HIV-2 LTR transcription initiation site was unchanged in either the presence or absence of Tat while the level of transcripts extending increasing distances from the HIV-2 LTR transcription initiation site were progressively stimulated in the presence of Tat. Though the HIV-1 Tat protein was a stronger inducer of HIV-1 LTR transcription than the HIV-2 Tat protein, we did not detect differences in the binding of these proteins to the HIV-1 and HIV-2 TAR RNAs. This suggested that differences in their transactivation properties may be due to alterations in their association with RNA polymerase II or associated elongation factors. (ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Tat functions to stimulate the elongation properties of transcription complexes paused by the duplicated TAR RNA element of human immunodeficiency virus 2. 749 Jul 54

Structures of the 31-kilodalton catalytic domain of rat DNA polymerase beta (pol beta) and the whole 39-kilodalton enzyme were determined at 2.3 and 3.6 angstrom resolution, respectively. The 31-kilodalton domain is composed of fingers, palm, and thumb subdomains arranged to form a DNA binding channel reminiscent of the polymerase domains of the Klenow fragment of Escherichia coli DNA polymerase I, HIV-1 reverse transcriptase, and bacteriophage T7 RNA polymerase. The amino-terminal 8-kilodalton domain is attached to the fingers subdomain by a flexible hinge. The two invariant aspartates found in all polymerase sequences and implicated in catalytic activity have the same geometric arrangement within structurally similar but topologically distinct palms, indicating that the polymerases have maintained, or possibly re-evolved, a common nucleotidyl transfer mechanism. The location of Mn2+ and deoxyadenosine triphosphate in pol beta confirms the role of the invariant aspartates in metal ion and deoxynucleoside triphosphate binding.
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PMID:Crystal structure of rat DNA polymerase beta: evidence for a common polymerase mechanism. 751 81


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