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)

Our previous reports established that immunization of mice in the footpad with a 15-amino acid synthetic peptide (R15K) from the V3 loop region in the envelope protein gp120 of human immunodeficiency virus type 1 (HIV-1) resulted in rapid induction of major histocompatability complex (MHC) class I-restricted, CD8+ HIV-1 envelope-specific cytotoxic T lymphocytes (CTLs) in the proximal popliteal lymph node. While efficient CTL activity could be assayed in lymph node cells for 8 to 10 weeks after a single injection, spleen cells from these mice showed low to negligible levels of specific CTLs at 4 to 8 weeks postimmunization. We tested immunizing mice with a noncovalent mixture of a helper T cell (Th) activity-inducing peptide and R15K and observed efficient induction of R15K-specific CTL response that could be assayed up to 8 weeks postimmunization in cells obtained from both lymph node and spleen. Efficient CTL priming was observed when Th peptides from either of two different conserved regions in the HIV env were mixed with R15K, containing a dipalmityl-lysine-glycine-glycine moiety at the amino terminus. These data confirm reports in literature describing requirement of Th activity for efficient priming of CTL response in vivo. Additionally, these studies strongly suggest the possibility of formulating potential vaccine candidates consisting of mixtures of synthetic peptides capable of inducing Th and CTL responses in the context of multiple MHC haplotypes.
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PMID:Use of helper T cell-inducing peptides from conserved regions in HIV-1 env in a noncovalent mixture with a CTL-inducing V3-loop peptide for in vivo induction of long-lasting systemic CTL response. 757 33

The third variable domain (V3 domain) of the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein gp120 contains a substantial number of positively charged amino acid residues. We previously demonstrated that mutation of basic amino acid residues at position 303, 306, 309, 313, and 325 in the V3 domain of HIV-1 strain NL4-3 resulted in a dramatic elimination of both virus infectivity and syncytium-inducing ability. Mutations of arginine at position 302 to serine (R302S) or lysine at position 320 to glutamine (K320Q) had variable effects on infectivity for a panel of T cell lines tested. These mutations are located on opposite sides of the Gly-Pro-Gly-Arg-Ala sequence in the center of the V3 domain. The R302S and K320Q mutations allowed us to determine if these basic residues are important for virus neutralization by polyanionic compounds. Dextran sulfate and heparin inhibited the cytopathogenicities of both mutants for MT-4 cells, although their 50% antiviral effective doses were slightly higher than those required to achieve complete protection against wild-type HIV-1NL4-3 replication. This result emphasizes that the basic amino acids of Arg302 and Lys320 are not essential for the inhibitory effect of dextran sulfate and heparin on HIV-1 infection.
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PMID:Single basic amino acid substitutions at position 302 or 320 in the V3 domain of HIV type 1 are not sufficient to alter the antiviral activity of dextran sulfate and heparin. 757 13

Rex of human T-cell leukemia virus type I (HTLV-I) and Rev of human immunodeficiency virus 1 (HIV-1) are post-transcriptional regulators of viral gene expression. By means of affinity chromatography, we purified an 18-kDa cellular protein that bound to the conserved leucine-motif/activation domain of HTLV-I Rex or HIV-1 Rev. The protein that was purified through a Rev-affinity column was found to bind to Rex immunoprecipitated with anti-Rex IgG from an HTLV-I-producing cell line. We analyzed the purified approximately 18-kDa protein biochemically and identified it as prothymosin alpha. The binding activity of prothymosin alpha to Rev or Rex was completely abolished when the epsilon-amino groups of its lysine residues were chemically modified by N-succinimidyl-3-(4-hydroxy-3,5-diodo- phenyl)propionate. The functional relationship between the nuclear protein prothymosin alpha and Rex-Rev is discussed.
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PMID:Binding of human prothymosin alpha to the leucine-motif/activation domains of HTLV-I Rex and HIV-1 Rev. 758 73

HIV-1 RT is able to catalyze DNA synthesis starting from mononucleotides used both as minimal primers and as nucleotide substrates (de novo synthesis) in the presence of a complementary template. The rate of this process is rather slow when compared to the polymerization primed by an oligonucleotide. The addition of tRNA(Lys,3) to this system increased the de novo synthesis rate by 2-fold. Addition of low concentrations of agents able to modify protein conformation, such as urea, dimethylsulfoxide and Triton X-100, can activate the de novo synthesis by a factor 2 to 5. A dramatic synergy is observed in the presence of the three compounds since the stimulating effect of tRNA increases 10-15 times. These results suggest that compounds activating RT are able to induce a conformational change of the enzyme which results in a higher specific activity. Primer tRNA seems to play an important role in HIV-1 RT modification(s) leading to a polymerase having a higher affinity for the primer or the dTTP, but not for the template. The specificity of RT for the template is not influenced by changes in the kinetics or in the thermodynamic parameters of the polymerization reaction.
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PMID:DNA synthesis primed by mononucleotides (de novo synthesis) catalyzed by HIV-1 reverse transcriptase: tRNA(Lys,3) activation. 758 77

The nucleocapsid protein NCp15 of human immunodeficiency virus type 1 (HIV-1) is a small basic protein with two zinc fingers. It is required for virion morphogenesis and synthesis of proviral DNA. As the first step in our study of the structural domains involved in the various functions of this protein, 18 monoclonal antibodies (MAbs) were isolated. The epitopes of NCp7 recognized by the MAbs were mapped using synthetic peptides representing overlapping sequences and truncated forms of NCp7. These anti-NCp7 MAbs were investigated by ELISA and real-time biospecific interaction analysis (BIAcore). Five classes of anti-NCp7 MAbs were characterized. Three classes (14 MAbs) were directed against continuous epitopes, one in the N-terminal part, another next to the second zinc finger and the third in the C-terminal part of the protein. Two other classes comprised four MAbs reacting only with the entire NCp7 and not with any of the small overlapping peptides used, suggesting that these MAbs were directed against conformational epitopes. The anti-NCp7 MAbs directed against linear epitopes were able to react efficiently with both NCp7 and NCp15, the NCp7 precursor, whereas the anti-NCp7 MAbs directed against conformational epitopes did not react with NCp15. Interestingly, most of the anti-NCp7 MAbs directed against conformational epitopes were capable of inhibiting the tight interaction between NCp7 and the HIV-1 replication primer tRNA(Lys,3). In contrast, most of the MAbs directed against linear epitopes did not inhibit this interaction.
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PMID:Conformational changes between human immunodeficiency virus type 1 nucleocapsid protein NCp7 and its precursor NCp15 as detected by anti-NCp7 monoclonal antibodies. 759 49

Biochemists at the New York University Medical Center assayed suppression of de novo p24 synthesis in HIV-inoculated MT-4 T lymphocytes to compare the effects of 4'-acetamidophenyl 4-guanidinobenzoate hydrochloride (AGB), Nalpha-p-tosyl-L-lysine chloro methyl ketone (TLCK), and nonoxynol-9 against HIV infection. Specifically, they wanted to determine the possibility that AGB, an antagonist of acrosin (a serine protease critical to sperm capacitation and to fortification of HIV infection), could launch a new class of vaginal spermicidal agents with anti-HIV activity. 100 mcg/ml AGB (a nontoxic dose) induced complete inhibition of HIV but did not affect the viability of MT-4 T lymphocytes. AGB had a 100 times more potent effect against HIV and had a lower cytotoxic effect (i.e., less irritating) than nonoxynol 9. These findings suggest that serine protease inhibitors, especially the guanidinobenzoates, have the potential to be effective vaginal contraceptives with anti-HIV activity.
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PMID:Acrosin inhibitor, 4'-acetamidophenyl 4-guanidinobenzoate, an experimental vaginal contraceptive with anti-HIV activity. 762 8

The intrinsic fluorescence of tyrosine increases by a factor of approximately two when the carboxy group is liberated from a peptide bond by hydrolysis. The increase in fluorescence provides a novel way to monitor the hydrolysis of native tyrosine peptides that contain only proteinogenic amino acids. Thus, for example, the hydrolysis by HIV-1 proteinase of a heptapeptide viral protein fragment gag129-135, Ser-Gln-Asn-Tyr-Pro-Ile-Val, was followed continuously at excitation and emission wavelengths 275 and 305 nm. The fluorescence increase is magnified by at least a factor of a thousand when a resonance energy quencher, such as paranitrophenylalanine, is in the vicinity. For example, the peptide Lys-Ala-Arg-Val-Tyr-Phe(p-NO2)-Glu-Ala-Nle-NH2 [Richards et al. (1990) J. Biol. Chem. 265, 7733], widely used for spectrophotometric assays of the HIV-1 proteinase, yields a substrate:product fluorescence ratio greater than 1:1000. Tyrosine-containing substrates of pepsin and trypsin showed similar behavior. The detection limit of the present method is at least one order of magnitude lower than absorbance assays of p-nitrophenylalanine peptides.
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PMID:Increase in fluorescence upon the hydrolysis of tyrosine peptides: application to proteinase assays. 766 86

A nonselective ex vivo assay was used to directly detect and quantify zidovudine (AZT)-resistant human immunodeficiency virus type 1 (HIV-1) in the blood of treated and untreated patients. In contrast to previous reports, drug-resistant virus was detected in peripheral blood mononuclear cells of a few of the patients who had never received AZT. The AZT resistance of HIV-1 isolates from one untreated individual was confirmed by further susceptibility studies in vitro and by the finding of a characteristic mutation (Lys-->Arg at codon 70) in the reverse transcriptase. In patients who were clinically stable while on AZT, HIV-1 titers in plasma and mononuclear cells were generally low but resistant viruses already predominated. In those individuals who were deteriorating despite AZT administration, high levels of viremia were observed, and the resistance phenotype was nearly universal. These findings serve to emphasize the magnitude of the AZT-resistance problem in patients on drug treatment.
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PMID:Quantitation of zidovudine-resistant human immunodeficiency virus type 1 in the blood of treated and untreated patients. 767 40

The [2',5'-bis-O-(tert-butyldimethylsilyl)-beta-D-ribofuranosyl]-3'- spiro-5"-(4"-amino-1",2"-oxathiole-2",2"-dioxide) (TSAO) derivatives of N1-methylhypoxanthine with linkage to the TSAO moiety through the N9 or N7 atom of the hypoxanthine ring (designated TSAO-m1Hx and 7-TSAO-m1Hx, respectively) are potent and selective inhibitors of human immunodeficiency virus type 1 (HIV-1) but not HIV-2 or simian immunodeficiency virus. Their selectivity indices (ratio of cytotoxic concentration to antivirally active concentration) are > 500. This is a > 15-fold increase in therapeutic index, compared with TSAO-adenine. A HIV-1(IIIB) variant selected for resistance to TSAO-m1Hx (designated HIV-1/TSAO-m1Hx) proved to be cross-resistant to the other TSAO-purine derivatives and to the TSAO-pyrimidine derivatives. However, HIV-1/TSAO-m1Hx was highly sensitive to the HIV-1-specific non-nucleoside tetrahydroimidazobenzodiazepinone, nevirapine, pyridinone L697,661, and several HEPT derivatives. The reverse transcriptase (RT) of HIV-1/TSAO-m1Hx shows a single amino acid change (138-Glu to Lys) that is identical to the amino acid change that has recently been observed in several HIV-1/TSAO-pyrimidine mutant strains. Our observations indicate that the TSAO-purines and TSAO-pyrimidines belong to one pharmacological class of HIV-1-specific RT inhibitors that are targeted at the same molecular site of the HIV-1 RT.
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PMID:Human immunodeficiency virus type 1-specific [2',5'-bis-O-(tert- butyldimethylsilyl)-beta-D-ribofuranosyl]-3'-spiro-5"-(4"-amino-1",2"- oxathiole-2",2"-dioxide)-purine analogues show a resistance spectrum that is different from that of the human immunodeficiency virus type 1-specific non-nucleoside analogues. 767 89

Site-directed mutagenesis has been used to assess the importance of lysine 263 in substrate binding of human immunodeficiency virus-1 (HIV-1) reverse transcriptase. Previous studies have indicated that lysine 263 functions in the binding of 2'-deoxynucleoside 5'-triphosphate (dNTP) substrates (Basu, A., Tirumalai, R. S., and Modak, M. J. (1989) J. Biol. Chem. 264, 8746-8752). We studied this interaction directly by using site-specific mutagenesis to change lysine 263 to a serine. Highly purified mutant enzyme K263S bound natural dNTP substrates and primed polynucleic acid substrates with equal affinity when compared to the wild type reverse transcriptase. No difference was observed in the binding of 3'-azido-2',3'-dideoxythymidine 5'-triphosphate to the mutant reverse transcriptase on the basis of Km and Ki determinations. The serine substitution had no effect on RNase H activity. These results indicate that lysine 263 is not essential in the binding of substrates to HIV-1 reverse transcriptase.
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PMID:Biochemical analysis of human immunodeficiency virus-1 reverse transcriptase containing a mutation at position lysine 263. 767 98


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