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)

The water-soluble ammonium salt of 3'-azido-5'-(O-ethoxycarbonylphosphinyl)-3'-deoxythymidine (ECP-AZT), the prototype of a novel class of compounds incorporating two active antiretroviral agents, in this case 3'-azido-3'-deoxythymidine (AZT) and phosphonoformic acid (PFA), within the same structure, was synthesized and tested as an inhibitor of the replication of human immunodeficiency virus type 1 (HIV-1) in Jurkat cells, a CD4+ human T-lymphocyte cell line. The corresponding 5'-(O-methoxycarbonylphosphinyl) derivative (MCP-AZT) was also prepared. The rationale for the synthesis of ECP-AZT and MCP-AZT was that they may be cleaved intracellularly to AZT and PFA via hydrolysis of the phosphate ester bond or to AZT 5'-monophosphate by oxidative cleavage of the carbon-phosphorus bond. ECP-AZT was found to block viral replication at a 50% inhibitory concentration (IC50) of ca. 10(-6) M as measured by reverse transcriptase (RT) activity in supernatants from cultures of infected cells. Little or no inhibition of cell growth was observed at this concentration, and there was less than 20% inhibition of cell growth at 10(-4) M. AZT itself was a more potent inhibitor of HIV-1 replication than ECP-AZT, but was also more cytotoxic. The antiviral selectivity of ECP-AZT, defined as the ratio IC50 (virus inhibition)/IC50(cell growth inhibition), was in the range considered to be therapeutic for anti-AIDS nucleosides.
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PMID:Inhibition of human immunodeficiency virus type 1 replication by phosphonoformate esters of 3'-azido-3'-deoxythymidine. 222 76

Blood samples to be tested for the presence of parasite DNA by using specific DNA probes are routinely stored in our laboratory as high-salt lysates (HSL). To safeguard against the risk of accidental infection with etiological agents such as the human immunodeficiency virus type 1 (HIV-1) while manipulating large numbers of blood samples in preparation for DNA probing, we determined the residual infectivity of HIV-1 after exposure to HSL components. Both high-titer virus stocks or provirus-carrying cells, suspended either in tissue culture medium or freshly drawn blood, were completely inactivated upon contact with the HSL components. This was verified by the absence of any detectable HIV-1-specific antigen in the supernatants of long-term cultures and the absence of virus-specific DNA fragments after amplification by polymerase chain reaction with DNA from such cultures as target DNA. These results support the conclusion that the virus is in fact completely inactivated by contact with the HSL components, rendering blood specimens stored as HSL noninfectious in regard to HIV-1.
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PMID:Inactivation of human immunodeficiency virus type 1 in blood samples stored as high-salt lysates. 227 31

Xylanpoly-(hydrogen sulphate) disodium salt with a molecular weight of about 6000 daltons (HOE/BAY 946) completely inhibited syncytium formation induced by the infection of T lymphocytes with HIV as well as viral replication at concentrations above 25 micrograms/ml. This dose was found to be inhibitory for several strains of HIV-1 and HIV-2. Low molecular weight fractions of the compound were less active against HIV, and high molecular derivatives were as active as HOE/BAY 946. A direct influence of the drug on the infectivity of the virus could not be demonstrated. The drug inhibited the reverse transcriptase of HIV. Treatment of permanently HIV-infected U937 cells resulted in a drastic reduction of virus particles released into the supernatant and points to an additional mode of action. A therapeutic effect of HOE/BAY 946 against retroviruses in vivo could be demonstrated in Friend leukaemia virus-infected mice. A clinical pilot study with the compound was started recently in Germany with AIDS patients who did not tolerate or refused to take zidovudine and with asymptomatic virus carriers.
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PMID:Inhibition of HIV and virus replication by polysulphated polyxylan: HOE/BAY 946, a new antiviral compound. 246 49

Three-dimensional computer models for two segments of the C terminus of gp41, the transmembrane AIDS envelope protein, which may form amphipathic alpha-helices, have been generated using structure prediction techniques combined with energy minimization and molecular dynamics simulations. Regions gp41(772-790) and gp41(828-848) of the HXB2 strain of HIV-1 display extraordinarily high hydrophobic moment maxima as alpha-helices and when in an antiparallel conformation exhibit charge complementarity, implying that they may bind with each other and associate with the membrane. The feasibility of this hypothesis was tested in a series of computer simulations of these peptides, extended by several residues to include additional charge pairing. Beginning with a trial structure in the form of antiparallel alpha-helices of segments 770-794 and 824-856, systematic axial rotations and displacements were used to generate alternative initial states. Molecular dynamics simulations with alpha-helical torsional restraints yielded several approximately cylindrical dimeric structures highly stabilized by numerous salt links and other hydrogen bonds. This suggests that these two regions may fold back on each other in antiparallel fashion to form a loop in the tertiary structure over residues 770-856, with the loop closed by membrane-associated amphipathic alpha-helices with charged sides facing each other. We speculate that such structures could aggregate to form channels or otherwise destabilize the membrane, thereby contributing to the cytopathic effects of the gp120-gp41 complex.
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PMID:Theoretically determined three-dimensional structures for amphipathic segments of the HIV-1 gp41 envelope protein. 254 49

Amplifiable hybridization probes--molecules with a probe sequence embedded within the sequence of a replicatable RNA--will promote the development of sensitive clinical assays. To demonstrate their utility, we prepared a recombinant RNA that contained a 30-nucleotide-long probe complementary to a conserved region of the pol gene in human immunodeficiency virus type 1 (HIV-1) mRNA. Test samples were prepared, each containing a different number of HIV-1 transcripts that served as simulated HIV-1 mRNA targets. Hybridizations were carried out in a solution containing the chaotropic salt, guanidine thiocyanate. Probe-target hybrids were isolated by reversible target capture on paramagnetic particles. The probes were then released from their targets and amplified by incubation with the RNA-directed RNA polymerase, Q beta replicase (EC 2.7.7.48). The replicase copied the probes in an exponential manner: after each round of copying, the number of RNA molecules doubled. The amount of RNA synthesized in each reaction (approximately 50 ng) was sufficient to measure without using radioisotopes. Kinetic analysis of the reactions demonstrated that the number of HIV-1 targets originally present in each sample could be determined by measuring the time it took to synthesize a particular amount of RNA (the longer the synthesis took, the fewer the number of targets originally present). The results suggest that clinical assays involving replicatable hybridization probes will be simple, accurate, sensitive, and automatable.
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PMID:Quantitative assays based on the use of replicatable hybridization probes. 267 78

The present study evaluates the utility of the dihydropyridine in equilibrium pyridinium salt redox system for the specific delivery and sustained release of a model 2',3'-dideoxynucleoside to the brain of mice as the initial effort in a search for agents that may prove effective in reversing the complicating neurological disorders of AIDS. The unsaturated nucleoside 2',3'-didehydro-2',3'-dideoxythymidine (1), which is effective in protecting ATH8 cells against the cytopathogenicity of HIV-1, was converted to the corresponding N-methyl-1,4-dihydronicotinate derivative, 4, in three steps. The 5'-O-nicotinate ester, 2, obtained by reaction of 1 with nicotinyl chloride, was converted in quantitative yield to the N-methylpyridinium salt 3 on treatment with MeI in acetone. Reduction of the latter with Na2S2O4 gave 4 in 50% yield. Pseudo-first-order rate constants for the oxidation of 4 to 3 were observed in plasma (k = 3.54 x 10(-5) s-1) and in homogenates of mouse liver (k = 9.2 x 10(-5) s-1) and brain (k = 8.85 x 10(-5) s-1). None of the chemical delivery system 4 could be detected in the brain of female BDF/1 mice at 1 h postinjection. The peak level of 3 in the brain occurred at 3 h with a half-life of 25 h. Both 1 and N-methylnicotinic acid (trigonelline, 5) were readily identified by HPLC in a brain homogenate derived from mice injected (25 mg/kg) with 4. TLC showed a low level penetration of mouse brain by 1 (0.44 microgram/g wet tissue) following injection of the corresponding labeled [methyl-3H]-2',3'-unsaturated nucleoside (25 mg/kg). The data indicate that 4 crosses the blood-brain barrier to be oxidized by cerebral tissue to the ionic structure 3, which is "locked therein". The sustained local release of a 2',3'-dideoxynucleoside, such as 1, from a chemical delivery system (4) represents a potentially useful approach to the treatment of AIDS dementia complex.
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PMID:A dihydropyridine carrier system for sustained delivery of 2',3'-dideoxynucleosides to the brain. 291 10

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 linear retrovirus DNA by the viral integrase (IN) into the host chromosome occurs by a concerted mechanism (full-site reaction). IN purified from avian myeloblastosis virus and using retrovirus-like DNA restriction fragments (487 bp in length) as donors and circular DNA (pGEM-3) as the target can efficiently catalyze that reaction. Nonionic detergent lysates of purified human immunodeficiency virus type 1 (HIV-1) virions were also capable of catalyzing the concerted integration reaction. The donor substrates were restriction fragments (469 bp) containing either U3-U5 (H-2 donor) or U5-U5 (H-5 donor) long terminal repeat sequences at their ends. As was shown previously with bacterially expressed HIV-1 IN, the U5 terminus of H-2 was preferred over the U3 terminus by virion-associated IN. The reactions involving two donors per circular target by HIV-1 IN preferred Mg2+ over Mn2+. Both metal ions were equally effective for the circular half-site reaction involving only one donor molecule. The linear 3.8-kbp recombinant products produced from two donor insertions into pGEM were genetically selected, and the donor-target junctions of individual recombinants were sequenced. A total of 55% of the 87 sequenced recombinants had host site duplications of between 5 and 7 bp, with the HIV-1 5-bp-specific duplication predominating. The other recombinants that migrated at the linear 3.8-kbp position were mainly small deletions that were grouped into four sets of 17, 27, 40, and 47 bp, each having a periodicity mimicking a turn of the DNA helix. Aprotic solvents (dimethyl sulfoxide and 1,4-dioxane) enhanced both the half-site and the linear 3.8-kbp strand transfer reactions which favored low-salt conditions (30 mM NaCl). The order of addition of the donor and target during preincubation with HIV-1 IN on ice did not affect the quantity of linear 3.8-kbp recombinants relative to that of the circular half-site products that were produced; only the quantity of donor-donor versus donor-target recombinants was affected. The presence of Mg2+ in the preincubation mixtures containing donor and target substrates was not necessary for the stability of preintegration complexes on ice or at 22 degrees C. Comparisons of the avian and HIV-1 concerted integration reactions are discussed.
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PMID:Concerted integration of retrovirus-like DNA by human immunodeficiency virus type 1 integrase. 766 12

The internal structural proteins of retroviruses are proteolytically processed from the Gag polyprotein, which alone is able to assemble into virus-like particles when expressed in cells. All Gag proteins contain domains corresponding to the three structural proteins MA, CA, and NC. We have expressed the CA and NC domains together as a unit in Escherichia coli, both for Rous sarcoma virus (RSV) and for human immunodeficiency virus type 1 (HIV-1). We also expressed a similar HIV-1 protein carrying the C-terminal p6 domain. RSV CA-NC, HIV-1 CA-NC, and HIV-1 CA-NC-p6 were purified in native form by classic methods. After adjustment of the pH and salt concentration, each of these proteins was found to assemble at a low level of efficiency into structures that resembled circular sheets and roughly spherical particles. The presence of RNA dramatically increased the efficiency of assembly, and in this case all three proteins formed hollow, cylindrical particles whose lengths were determined by the size of the RNA. The optimal pH at which assembly occurred was 5.5 for the RSV protein and 8.0 for the HIV-1 proteins. The treatment of the RSV CA-NC cylindrical particles with nonionic detergent, with ribonuclease, or with viral protease caused disassembly. These results suggest that RNA plays an important structural role in the virion and that it may initiate and organize the assembly process. The in vitro system described should facilitate the dissection of assembly pathways in retroviruses.
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PMID:Self-assembly in vitro of purified CA-NC proteins from Rous sarcoma virus and human immunodeficiency virus type 1. 766 50

The conserved aspartic acid residue 488 in the RNase H domain of HIV-1 reverse transcriptase (RT) was mutated to alanine. RT was expressed in Escherichia coli alone or with the entire pol-gene polyprotein consisting of proteinase, RT, and integrase and processed by the HIV-1 proteinase in the bacterial cell. Expression of mutant RT together with the proteinase resulted in an overproduction of RT p51 vs p66. The mutation also altered the conformation of the RT p66/p51 heterodimer as shown by the loss of binding of monoclonal antibodies to mutant RT in ELISA. Crystallographic data shows that a salt bridge exists between Asp 488 and Lys 465 of RNase H which stabilizes the uncleavable form of RT p66, and that substitution of Asp for Ala would prevent the formation of this salt bridge. Our results indicate that disruption of this salt bridge through mutation of Asp 488 interferes with the conformational changes that regulate the limited processing of p66 to 51 by the virus proteinase. Homology data suggest that such a bridge may be present in other lentiviruses. The mutation introduced caused a moderate decrease in both the RNase H activity and the polymerase activity of RT, indicating that the proper folding of the RNase H domain of RT is necessary to achieve full polymerase activity.
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PMID:Disruption of a salt bridge between Asp 488 and Lys 465 in HIV-1 reverse transcriptase alters its proteolytic processing and polymerase activity. 769 May 4


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