scholarly journals Co-expression of a trans-dominant negative mutant of the human immunodeficiency virus type 1 (HIV-1) Rev protein affects the Rev-dependent splicing pattern and expression of HIV-1 RNAs

1999 ◽  
Vol 80 (8) ◽  
pp. 1965-1974 ◽  
Author(s):  
Anne Marie Szilvay ◽  
Stig-Ove Bøe ◽  
Karl-Henning Kalland
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Dominant Negative ◽  
Structural Proteins ◽  
Dominant Negative Mutant ◽  
Wild Type ◽  
Immunodeficiency Virus ◽  
Hiv 1 ◽  
Negative Mutant

Trans-dominant negative mutants of the human immunodeficiency virus type 1 (HIV-1) regulatory protein Rev inhibit the function of wild-type Rev in a dose-dependent manner. This was previously shown to be caused by nuclear retention of the wild-type protein. In the present work, further analysis of the trans-dominant negative effect was performed using cotransfection experiments with different constructs encoding HIV-1 Rev and viral structural proteins together with a plasmid encoding a trans-dominant negative Rev mutant. Thus, one species of pre-mRNA was transcribed from the reporter plasmids. This pre-mRNA was then either spliced or exported by Rev as unspliced RNA for translation of the HIV structural proteins. An immunofluorescence assay and Western blot analysis were used for analysis of protein expression. In situ hybridization was applied for labelling of unspliced mRNA in transfected cells, and RNase protection analysis was used to determine the relative amount of unspliced versus spliced mRNAs. The experiments confirmed that the trans-dominant negative mutant inhibited nuclear export of unspliced mRNA. It was, in addition, demonstrated for the first time that the trans-dominant negative mutant also affected a Rev-dependent regulatory step connected with viral pre-mRNA splicing. As a consequence, proteins expressed from unspliced and singly spliced HIV mRNAs decreased while there was an increase in protein products encoded by spliced and alternatively spliced mRNAs.

scholarly journals Human Ubc9 Contributes to Production of Fully Infectious Human Immunodeficiency Virus Type 1 Virions

2009 ◽  
Vol 83 (20) ◽  
pp. 10448-10459 ◽  
Author(s):  
Tareq Jaber ◽  
Christopher R. Bohl ◽  
Gentry L. Lewis ◽  
Charles Wood ◽  
John T. West ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Normal Numbers ◽  
Gag Protein ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Ubc9 was identified as a cellular protein that interacts with the Gag protein of Mason-Pfizer monkey virus. We show here that Ubc9 also interacts with the human immunodeficiency virus type 1 (HIV-1) Gag protein and that their interaction is important for virus replication. Gag was found to colocalize with Ubc9 predominantly at perinuclear puncta. While cells in which Ubc9 expression was suppressed with RNA interference produced normal numbers of virions, these particles were 8- to 10-fold less infectious than those produced in the presence of Ubc9. The nature of this defect was assayed for dependence on Ubc9 during viral assembly, trafficking, and Env incorporation. The Gag-mediated assembly of virus particles and protease-mediated processing of Gag and Gag-Pol were unchanged in the absence of Ubc9. However, the stability of the cell-associated Env glycoprotein was decreased and Env incorporation into released virions was altered. Interestingly, overexpression of the Ubc9 trans-dominant-negative mutant C93A, which is a defective E2-SUMO-1 conjugase, suggests that this activity may not be required for interaction with Gag, virion assembly, or infectivity. This finding demonstrates that Ubc9 plays an important role in the production of infectious HIV-1 virions.

scholarly journals Human Immunodeficiency Virus Type 1 Tat Protein Activates Transcription Factor NF-κB through the Cellular Interferon-Inducible, Double-Stranded RNA-Dependent Protein Kinase, PKR

1999 ◽  
Vol 73 (8) ◽  
pp. 7080-7086 ◽  
Author(s):  
Francesca Demarchi ◽  
Maria Ines Gutierrez ◽  
Mauro Giacca
Keyword(s):  
Human Immunodeficiency Virus ◽  
Protein Kinase ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Nuclear Factor Κb ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The transactivator protein of human immunodeficiency virus type 1 (HIV-1) (Tat) is a powerful activator of nuclear factor-κB (NF-κB), acting through degradation of the inhibitor IκB-α (F. Demarchi, F. d’Adda di Fagagna, A. Falaschi, and M. Giacca, J. Virol. 70:4427–4437, 1996). Here, we show that this activity of Tat requires the function of the cellular interferon-inducible protein kinase PKR. Tat-mediated NF-κB activation and transcriptional induction of the HIV-1 long terminal repeat were impaired in murine cells in which the PKR gene was knocked out. Both functions were restored by cotransfection of Tat with the cDNA for PKR. Expression of a dominant-negative mutant of PKR specifically reduced the levels of Tat transactivation in different human cell types. Activation of NF-κB by Tat required integrity of the basic domain of Tat; previous studies have indicated that this domain is necessary for specific Tat-PKR interaction.

scholarly journals Different Abilities of Escape Mutant-Specific Cytotoxic T Cells To Suppress Replication of Escape Mutant and Wild-Type Human Immunodeficiency Virus Type 1 in New Hosts

2007 ◽  
Vol 82 (1) ◽  
pp. 138-147 ◽  
Author(s):  
Mamoru Fujiwara ◽  
Junko Tanuma ◽  
Hirokazu Koizumi ◽  
Yuka Kawashima ◽  
Kazutaka Honda ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Escape Mutant ◽  
Wild Type ◽  
Specific Ctls ◽  
Immunodeficiency Virus ◽  
New Hosts ◽  
Hiv 1 ◽  
Hla Molecules

ABSTRACT There is much evidence that in human immunodeficiency virus type 1 (HIV-1)-infected individuals, strong cytotoxic T lymphocyte (CTL)-mediated immune pressure results in the selection of HIV-1 mutants that have escaped from wild-type-specific CTLs. If escape mutant-specific CTLs are not elicited in new hosts sharing donor HLA molecules, the transmission of these mutants results in the accumulation of escape mutants in the population. However, whether escape mutant-specific CTLs are definitively not elicited in new hosts sharing donor HLA molecules still remains unclear. A previous study showed that a Y-to-F substitution at the second position (2F) of the Nef138-10 epitope is significantly detected in HLA-A*2402+ hemophilic donors. Presently, we confirmed that this 2F mutant was an escape mutant by demonstrating strong and weak abilities of Nef138-10-specific CTL clones to suppress replication of the wild-type and 2F mutant viruses, respectively. We demonstrated the existence of the 2F-specific CTLs in three new hosts who had been primarily infected with the 2F mutant. The 2F-specific CTL clones suppressed the replication of both wild-type and mutant viruses. However, the abilities of these clones to suppress replication of the 2F virus were much weaker than those of wild-type-specific and the 2F-specific ones to suppress replication of the wild-type virus. These findings indicate that the 2F mutant is conserved in HIV-1-infected donors having HLA-A*2402, because the 2F-specific CTLs failed to completely suppress the 2F mutant replication and effectively prevented viral reversion in new hosts carrying HLA-A*2402.

scholarly journals Mutational Analysis of the Hydrophobic Tail of the Human Immunodeficiency Virus Type 1 p6Gag Protein Produces a Mutant That Fails To Package Its Envelope Protein

1999 ◽  
Vol 73 (1) ◽  
pp. 19-28 ◽  
Author(s):  
David E. Ott ◽  
Elena N. Chertova ◽  
Laura K. Busch ◽  
Lori V. Coren ◽  
Tracy D. Gagliardi ◽  
...  
Keyword(s):  
Amino Acids ◽  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Human Immunodeficiency Virus Type ◽  
Wild Type ◽  
Immunodeficiency Virus ◽  
Hydrophobic Tail ◽  
Carboxyl Terminal ◽  
Hiv 1

ABSTRACT The p6Gag protein of human immunodeficiency virus type 1 (HIV-1) is produced as the carboxyl-terminal sequence within the Gag polyprotein. The amino acid composition of this protein is high in hydrophilic and polar residues except for a patch of relatively hydrophobic amino acids found in the carboxyl-terminal 16 amino acids. Internal cleavage of p6Gag between Y36 and P37, apparently by the HIV-1 protease, removes this hydrophobic tail region from approximately 30% of the mature p6Gag proteins in HIV-1MN. To investigate the importance of this cleavage and the hydrophobic nature of this portion of p6Gag, site-directed mutations were made at the minor protease cleavage site and within the hydrophobic tail. The results showed that all of the single-amino-acid-replacement mutants exhibited either reduced or undetectable cleavage at the site yet almost all were nearly as infectious as wild-type virus, demonstrating that processing at this site is not important for viral replication. However, one exception, Y36F, was 300-fold as infectious the wild type. In contrast to the single-substitution mutants, a virus with two substitutions in this region of p6Gag, Y36S-L41P, could not infect susceptible cells. Protein analysis showed that while the processing of the Gag precursor was normal, the double mutant did not incorporate Env into virus particles. This mutant could be complemented with surface glycoproteins from vesicular stomatitis virus and murine leukemia virus, showing that the inability to incorporate Env was the lethal defect for the Y36S-L41P virus. However, this mutant was not rescued by an HIV-1 Env with a truncated gp41TM cytoplasmic domain, showing that it is phenotypically different from the previously described MA mutants that do not incorporate their full-length Env proteins. Cotransfection experiments with Y36S-L41P and wild-type proviral DNAs revealed that the mutant Gag dominantly blocked the incorporation of Env by wild-type Gag. These results show that the Y36S-L41P p6Gag mutation dramatically blocks the incorporation of HIV-1 Env, presumably acting late in assembly and early during budding.

scholarly journals The Thiocarboxanilide Nonnucleoside Inhibitor UC781 Restores Antiviral Activity of 3′-Azido-3′-Deoxythymidine (AZT) against AZT-Resistant Human Immunodeficiency Virus Type 1

1999 ◽  
Vol 43 (2) ◽  
pp. 259-263 ◽  
Author(s):  
Gadi Borkow ◽  
Dominique Arion ◽  
Mark A. Wainberg ◽  
Michael A. Parniak
Keyword(s):  
Human Immunodeficiency Virus ◽  
Antiviral Activity ◽  
Reverse Transcriptase ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Wild Type Virus ◽  
Wild Type ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT N-[4-Chloro-3-(3-methyl-2-butenyloxy)phenyl]-2-methyl-3-furancarbothioamide (UC781) is an exceptionally potent nonnucleoside inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase. We found that a 1:1 molar combination of UC781 and 3′-azido-3′-deoxythymidine (AZT) showed high-level synergy in inhibiting the replication of AZT-resistant virus, implying that UC781 can restore antiviral activity to AZT against AZT-resistant HIV-1. Neither the nevirapine plus AZT nor the 2′,5′-bis-O-(t-butyldimethylsilyl)-3′-spiro-5"-(4"-amino-1",2"-oxathiole-2",2"-dioxide plus AZT combinations had this effect. Studies with purified HIV-1 reverse transcriptase (from a wild type and an AZT-resistant mutant) showed that UC781 was a potent inhibitor of the pyrophosphorolytic cleavage of nucleotides from the 3′ end of the DNA polymerization primer, a process that we have proposed to be critical for the phenotypic expression of AZT resistance. Combinations of UC781 plus AZT did not act in synergy to inhibit the replication of either wild-type virus or UC781-resistant HIV-1. Importantly, the time to the development of viral resistance to combinations of UC781 plus AZT is significantly delayed compared to the time to the development of resistance to either drug alone.

scholarly journals Activity against Human Immunodeficiency Virus Type 1, Intracellular Metabolism, and Effects on Human DNA Polymerases of 4′-Ethynyl-2-Fluoro-2′-Deoxyadenosine

2007 ◽  
Vol 51 (8) ◽  
pp. 2701-2708 ◽  
Author(s):  
Hirotomo Nakata ◽  
Masayuki Amano ◽  
Yasuhiro Koh ◽  
Eiichi Kodama ◽  
Guangwei Yang ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Transcriptase Inhibitor ◽  
Multidrug Resistant ◽  
Wild Type ◽  
Immunodeficiency Virus ◽  
Reverse Transcriptase Inhibitor ◽  
Hiv 1

ABSTRACT We examined the intracytoplasmic anabolism and kinetics of antiviral activity against human immunodeficiency virus type 1 (HIV-1) of a nucleoside reverse transcriptase inhibitor, 4′-ethynyl-2-fluoro-2′-deoxyadenosine (EFdA), which has potent activity against wild-type and multidrug-resistant HIV-1 strains. When CEM cells were exposed to 0.1 μM [3H]EFdA or [3H]3′-azido-2′,3′-dideoxythymidine (AZT) for 6 h, the intracellular EFdA-triphosphate (TP) level was 91.6 pmol/109 cells, while that of AZT was 396.5 pmol/109 cells. When CEM cells were exposed to 10 μM [3H]EFdA, the amount of EFdA-TP increased by 22-fold (2,090 pmol/109 cells), while the amount of [3H]AZT-TP increased only moderately by 2.4-fold (970 pmol/109 cells). The intracellular half-life values of EFdA-TP and AZT-TP were ∼17 and ∼3 h, respectively. When MT-4 cells were cultured with 0.01 μM EFdA for 24 h, thoroughly washed to remove EFdA, further cultured without EFdA for various periods of time, exposed to HIV-1NL4-3, and cultured for an additional 5 days, the protection values were 75 and 47%, respectively, after 24 and 48 h with no drug incubation, while those with 1 μM AZT were 55 and 9.2%, respectively. The 50% inhibitory concentration values of EFdA-TP against human polymerases α, β, and γ were >100 μM, >100 μM, and 10 μM, respectively, while those of ddA-TP were >100 μM, 0.2 μM, and 0.2 μM, respectively. These data warrant further development of EFdA as a potential therapeutic agent for those patients who harbor wild-type HIV-1 and/or multidrug-resistant variants.

scholarly journals Multiple human immunodeficiency virus type 1 Nef functions contribute to efficient replication in primary human macrophages

2004 ◽  
Vol 85 (6) ◽  
pp. 1463-1469 ◽  
Author(s):  
Amanda Brown ◽  
Shaghayegh Moghaddam ◽  
Thomas Kawano ◽  
Cecilia Cheng-Mayer
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Single Point ◽  
Wild Type Virus ◽  
Wild Type ◽  
Immunodeficiency Virus ◽  
Efficient Replication ◽  
Hiv 1

The human immunodeficiency virus type 1 (HIV-1) Nef protein has been shown to accelerate viral growth kinetics in primary human T-lymphocytes and macrophages; however, the specific function(s) of Nef responsible for this phenotype in macrophages is unknown. To address this issue, mutants of a molecularly cloned macrophage-tropic isolate, HIV-1SF162, were generated expressing single point mutations that abrogate the ability of Nef to interact with cellular kinases or mediate CD4 down-regulation. Infection of primary monocyte-derived macrophages (MDM) with these mutant viruses revealed that residues in the PXXP motif contribute to efficient replication. Interestingly, viruses expressing alleles of Nef defective in CD4 down-modulation activity retain wild-type levels of infectivity in single-round assays but exhibited delayed replication kinetics and grew to lower titres compared to the wild-type virus in MDM. These data suggest that efficient HIV-1 replication is dependent on the ability of Nef to interact with cellular kinases and remove CD4 from the surface of infected macrophages.

scholarly journals High Potency of Indolyl Aryl Sulfone Nonnucleoside Inhibitors towards Drug-Resistant Human Immunodeficiency Virus Type 1 Reverse Transcriptase Mutants Is Due to Selective Targeting of Different Mechanistic Forms of the Enzyme

2005 ◽  
Vol 49 (11) ◽  
pp. 4546-4554 ◽  
Author(s):  
Reynel Cancio ◽  
Romano Silvestri ◽  
Rino Ragno ◽  
Marino Artico ◽  
Gabriella De Martino ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Reverse Transcriptase ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Mechanism Of Action ◽  
Drug Resistant ◽  
Wild Type ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Indolyl aryl sulfone (IAS) nonnucleoside inhibitors have been shown to potently inhibit the growth of wild-type and drug-resistant human immunodeficiency virus type 1 (HIV-1), but their exact mechanism of action has not been elucidated yet. Here, we describe the mechanism of inhibition of HIV-1 reverse transcriptase (RT) by selected IAS derivatives. Our results showed that, depending on the substitutions introduced in the IAS common pharmacophore, these compounds can be made selective for different enzyme-substrate complexes. Moreover, we showed that the molecular basis for this selectivity was a different association rate of the drug to a particular enzymatic form along the reaction pathway. By comparing the activities of the different compounds against wild-type RT and the nonnucleoside reverse transcriptase inhibitor-resistant mutant Lys103Asn, it was possible to hypothesize, on the basis of their mechanism of action, a rationale for the design of drugs which could overcome the steric barrier imposed by the Lys103Asn mutation.

scholarly journals Identification of novel thiocarboxanilide derivatives that suppress a variety of drug-resistant mutant human immunodeficiency virus type 1 strains at a potency similar to that for wild-type virus.

1996 ◽  
Vol 40 (6) ◽  
pp. 1454-1466 ◽  
Author(s):  
J Balzarini ◽  
W G Brouwer ◽  
D C Dao ◽  
E M Osika ◽  
E De Clercq
Keyword(s):  
Human Immunodeficiency Virus ◽  
Reverse Transcriptase ◽  
Human Immunodeficiency Virus Type ◽  
Effective Concentration ◽  
Mutant Virus ◽  
Wild Type ◽  
Immunodeficiency Virus ◽  
Virus Strains ◽  
Hiv 1

A large variety of carboxanilide and thiocarboxanilide derivatives in which the original oxathiin or aliphatic moieties present in the prototype compounds UC84 and UC38 were replaced by an (un) substituted furanyl, thienyl, phenyl, or pyrrole entity have been evaluated for activity against wild-type human immunodeficiency virus type 1 strain IIIB [HIV-1 (IIIB)] and a series of mutant virus strains derived thereof. The mutant viruses contained either the Leu-100-->Ile, Lys-103-->Asn, Val-106-->Ala, Glu-138-->Lys, Tyr-181-->Cys, or Tyr-188-->Leu mutation in their reverse transcriptase. Several 3-(2-methylfuranyl)- and 3-(2-methylthienyl)-thiocarboxanilide ester, (thio)ether, and oxime ether derivatives showed exquisitely potent antiviral activity against wild-type HIV-1 (50% effective concentration, 0.009 to 0.021 microM). The pentenylethers of the 2-methylfuranyl and 2-methylthienyl derivatives (i.e., 313, N-[4-chloro-3-(3-methyl-2-butenyloxy)phenyl]- 2-methyl-3-furancarbothioamide or UC-781, and 314, N-[4-chloro-3-(3-methyl-2-butenyloxy)phenyl] -2-methyl-3-thiophenecarbothioamide or UC-82) proved virtually equally inhibitory for wild-type and the Ile-100, Ala-106, and Lys-138 mutant virus strains (50% effective concentration, 0.015 to 0.021 microM). Their inhibitory effect against the Asn-103 and Cys-181 reverse transcriptase mutant virus strains was decreased only four- to sevenfold compared with wildtype virus. UC-781 and UC-82 should be considered potential candidate drugs for the treatment of HIV-1-infected individuals.

scholarly journals Intracellular Substrates for the Primer-Unblocking Reaction by Human Immunodeficiency Virus Type 1 Reverse Transcriptase: Detection and Quantitation in Extracts from Quiescent- and Activated-Lymphocyte Subpopulations

2005 ◽  
Vol 49 (5) ◽  
pp. 1761-1769 ◽  
Author(s):  
Anthony J. Smith ◽  
Peter R. Meyer ◽  
Deshratn Asthana ◽  
Margarita R. Ashman ◽  
Walter A. Scott
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
Reverse Transcriptase ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Wild Type ◽  
Cell Extracts ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Treatment of human immunodeficiency virus type 1 (HIV-1)-infected patients with 3′-azido-3′-deoxythymidine (AZT) selects for mutant forms of viral reverse transcriptase (RT) with increased ability to remove chain-terminating nucleotides from blocked DNA chains. We tested various cell extracts for the presence of endogenous acceptor substrates for this reaction. Cell extracts incubated with HIV-1 RT and [32P]ddAMP-terminated DNA primer/template gave rise to 32P-labeled adenosine 2′,3′-dideoxyadenosine 5′,5′′′−P1,P4-tetraphosphate (Ap4ddA), ddATP, Gp4ddA, and Ap3ddA, corresponding to the transfer of [32P]ddAMP to ATP, PPi, GTP, and ADP, respectively. Incubation with [32P]AZT monophosphate (AZTMP)-terminated primer/template gave rise to the analogous 32P-labeled AZT derivatives. Based on the rates of formation of the specific excision products, ATP and PPi levels were determined: ATP was present at 1.3 to 2.2 mM in H9 cells, macrophages, and unstimulated CD4+ or CD8+ T cells, while PPi was present at 7 to 15 μM. Under these conditions, the ATP-dependent reaction predominated, and excision by the AZT-resistant mutant RT was more efficient than wild type RT. Activated CD4+ or CD8+ T cells contained 1.4 to 2.7 mM ATP and 55 to 79 μM PPi. These cellular PPi concentrations are lower than previously reported; nonetheless, the PPi-dependent reaction predominated in extracts from activated T cells, and excision by mutant and wild-type RT occurred with similar efficiency. While PPi-dependent excision may contribute to AZT resistance in vivo, it is likely that selection of AZT-resistant mutants occurs primarily in an environment where the ATP-dependent reaction predominates.

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