scholarly journals Low TRBP Levels Support an Innate Human Immunodeficiency Virus Type 1 Resistance in Astrocytes by Enhancing the PKR Antiviral Response

2005 ◽  
Vol 79 (20) ◽  
pp. 12763-12772 ◽  
Author(s):  
Chi L. Ong ◽  
Janine C. Thorpe ◽  
Paul R. Gorry ◽  
Sylvie Bannwarth ◽  
Anthony Jaworowski ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Rna Binding ◽  
Rna Binding Protein ◽  
Antiviral Response ◽  
Immunodeficiency Virus ◽  
Low Levels ◽  
Hiv 1

ABSTRACT Acute human immunodeficiency virus type 1 (HIV-1) replication in astrocytes produces minimal new virus particles due, in part, to inefficient translation of viral structural proteins despite high levels of cytoplasmic viral mRNA. We found that a highly reactive double-stranded (ds) RNA-binding protein kinase (PKR) response in astrocytes underlies this inefficient translation of HIV-1 mRNA. The dsRNA elements made during acute replication of HIV-1 in astrocytes triggers PKR activation and the specific inhibition of HIV-1 protein translation. The heightened PKR response results from relatively low levels of the cellular antagonist of PKR, the TAR RNA binding protein (TRBP). Efficient HIV-1 production was restored in astrocytes by inhibiting the innate PKR response to HIV-1 dsRNA with dominant negative PKR mutants, or PKR knockdown by siRNA gene silencing. Increasing the expression of TRBP in astrocytes restored acute virus production to levels comparable to those observed in permissive cells. Therefore, the robust innate PKR antiviral response in astrocytes results from relatively low levels of TRBP expression and contributes to their restricted infection. Our findings highlight TRBP as a novel cellular target for therapeutic interventions to block productive HIV-1 replication in cells that are fully permissive for HIV-1 infection.

scholarly journals CCR5Δ32 Protein Expression and Stability Are Critical for Resistance to Human Immunodeficiency Virus Type 1 In Vivo

2007 ◽  
Vol 81 (15) ◽  
pp. 8041-8049 ◽  
Author(s):  
Lokesh Agrawal ◽  
Qingwen Jin ◽  
Jeff Altenburg ◽  
L. Meyer ◽  
R. Tubiana ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Protein Expression ◽  
Protective Effect ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Immunodeficiency Virus ◽  
Low Levels ◽  
Hiv 1

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) infection of individuals carrying the two alleles of the CCR5Δ32 mutation (CCR5−/−) has rarely been reported, but how the virus overcomes the CCR5Δ32 protective effect in these cases has not been delineated. We have investigated this in 6 infected (HIV+) and 25 HIV− CCR5−/− individuals. CD4+ T lymphocytes isolated from HIV− CCR5−/− peripheral blood mononuclear cells (PBMCs) showed lower levels of CXCR4 expression that correlated with lower X4 Env-mediated fusion. Endogenous CCR5Δ32 protein was detected in all HIV− CCR5−/− PBMC samples (n = 25) but not in four of six unrelated HIV+ CCR5−/− PBMC samples. Low levels were detected in another two HIV+ CCR5−/− PBMC samples. The expression of adenovirus 5 (Ad5)-encoded CCR5Δ32 protein restored the protective effect in PBMCs from three HIV+ CCR5−/− individuals but failed to restore the protective effect in PBMCs isolated from another three HIV+ CCR5−/− individuals. In the latter samples, pulse-chase analyses demonstrated the disappearance of endogenous Ad5-encoded CCR5Δ32 protein and the accumulation of Ad5-encoded CCR5 during the chase periods. PBMCs isolated from CCR5−/− individuals showed resistance to primary X4 but were readily infected by a lab-adapted X4 strain. Low levels of Ad5-encoded CCR5Δ32 protein conferred resistance to primary X4 but not to lab-adapted X4 virus. These data provide strong support for the hypothesis that the CCR5Δ32 protein actively confers resistance to HIV-1 in vivo and suggest that the loss or reduction of CCR5Δ32 protein expression may account for HIV-1 infection of CCR5−/− individuals. The results also suggest that other cellular or virally induced factors may be involved in the stability of CCR5Δ32 protein.

scholarly journals Low Levels of Human Immunodeficiency Virus Type 1 DNA in High-Risk Seronegative Men

2005 ◽  
Vol 79 (10) ◽  
pp. 6551-6553 ◽  
Author(s):  
Fransje A. Koning ◽  
Teun J. K. van der Vorst ◽  
Hanneke Schuitemaker
Keyword(s):  
Human Immunodeficiency Virus ◽  
High Risk ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Peripheral Blood Mononuclear ◽  
Immunodeficiency Virus ◽  
High Prevalence ◽  
Low Levels ◽  
Hiv 1

ABSTRACT We detected human immunodeficiency virus type 1 (HIV-1) DNA at very low levels in sequential peripheral blood mononuclear cell samples of five out of six high-risk, seronegative, homosexual men and five out of five individuals 7.8 to 1.6 years prior to seroconversion. These data indicate a high prevalence of low-level HIV-1 DNA in exposed seronegative individuals.

scholarly journals Redundant Roles for Nucleocapsid and Matrix RNA-Binding Sequences in Human Immunodeficiency Virus Type 1 Assembly

2005 ◽  
Vol 79 (22) ◽  
pp. 13839-13847 ◽  
Author(s):  
David E. Ott ◽  
Lori V. Coren ◽  
Tracy D. Gagliardi
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Matrix Protein ◽  
Particle Production ◽  
Rna Binding ◽  
Immunodeficiency Virus ◽  
The Matrix ◽  
Hiv 1

ABSTRACT RNA appears to be required for the assembly of retroviruses. This is likely due to binding of RNA by multiple Gags, which in turn organizes and stabilizes the Gag-Gag interactions that form the virion. While the nucleocapsid (NC) domain is the most conspicuous RNA-binding region of the human immunodeficiency virus type 1 (HIV-1) Gag polyprotein, we have previously shown that NC is not strictly required for efficient particle production. To determine if an RNA requirement for HIV-1 assembly exists, we analyzed virions produced by an NC deletion mutant for the presence of RNA. The results revealed that virions without NC still contained significant amounts of RNA. Since these packaged RNAs are probably incorporated by other RNA-binding sequences in Gag, an RNA-binding site in the matrix protein (MA) of Gag was mutated. While this mutation did not interfere with HIV-1 replication, a construct with both MA and NC mutations (MX/NX) failed to produce particles. The MX/NX mutant was rescued in trans by coassembly with several forms of Gag: wild-type Gag, either of the single-mutant Gags, or Gag truncations that contain MA or NC sequences. Addition of basic sequences to the MX/NX mutant partially restored particle production, consistent with a requirement for Gag-RNA binding in addition to Gag-Gag interactions. Together, these results support an RNA-binding requirement for Gag assembly, which relies on binding of RNA by MA or NC sequences to condense, organize, and stabilize the HIV-1 Gag-Gag interactions that form the virion.

scholarly journals Interaction of YB-1 with human immunodeficiency virus type 1 Tat and TAR RNA modulates viral promoter activity

1999 ◽  
Vol 80 (10) ◽  
pp. 2629-2638 ◽  
Author(s):  
Sameer A. Ansari ◽  
Mahmut Safak ◽  
Gary L. Gallia ◽  
Bassel E. Sawaya ◽  
Shohreh Amini ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Rna Binding ◽  
Regulatory Element ◽  
Binding Activity ◽  
Full Length ◽  
Immunodeficiency Virus ◽  
Hiv 1

Transcriptional regulation of the human immunodeficiency virus type 1 (HIV-1) genome is mediated by viral and cellular factors. TAR, an unusual RNA regulatory element with a stem–bulge–loop structure at the 5′ ends of all nascent viral transcripts is critical for HIV-1 transcription. TAR is the target for Tat, a viral transcription factor encoded early in the HIV-1 life-cycle and essential for gene expression. Evidence demonstrating the interaction of a cellular ssDNA/RNA binding protein, YB-1, with TAR through a region which is important for Tat interaction is presented. Interestingly, results from protein–protein interaction studies revealed that YB-1 can also form a complex with Tat. Results from mapping experiments suggest that while the region spanning aa 125–203 within YB-1 is essential for its association with TAR, a truncated YB-1 spanning aa 1–125 can weakly bind to Tat. Functionally, overexpression of full-length YB-1 enhanced Tat-induced activation of the HIV-1 minimal promoter containing TAR sequences, whereas mutant YB-1 with no ability to bind to Tat and TAR failed to affect Tat-mediated activation. Expression of mutant YB-1(1–125), which binds to Tat but not RNA, decreased Tat- mediated enhancement of virus transcription. These observations suggest that while full-length YB-1 may function as a facilitator and, by interaction with both Tat and TAR, increase the level of Tat:TAR association, mutant YB-1 with no TAR binding activity, by complexing with Tat, may prevent Tat interaction with TAR. The importance of these findings in light of the proposed mechanism of Tat function is discussed.

scholarly journals Persistence of Extraordinarily Low Levels of Genetically Homogeneous Human Immunodeficiency Virus Type 1 in Exposed Seronegative Individuals

2003 ◽  
Vol 77 (11) ◽  
pp. 6108-6116 ◽  
Author(s):  
Tuofu Zhu ◽  
Lawrence Corey ◽  
Yon Hwangbo ◽  
Jean M. Lee ◽  
Gerald H. Learn ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
High Risk ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Immunodeficiency Virus ◽  
Specific Cytotoxicity ◽  
Low Levels ◽  
And Control ◽  
Hiv 1

ABSTRACT Some individuals remain inexplicably seronegative and lack evidence for human immunodeficiency virus type 1 (HIV-1) infection by conventional serologic or virologic testing despite repeated high-risk virus exposures. Here, we examined 10 exposed seronegative (ES) individuals exhibiting HIV-1-specific cytotoxicity for the presence of HIV-1. We discovered HIV-1 DNA in resting CD4+ T cells (mean, 0.05 ± 0.01 copies per million cells) at multiple visits spanning 69 to 130 weeks in two ES individuals at levels that were on average 104- to 106-fold lower than those of other HIV-1-infected populations reported. Sequences of HIV-1 envelope and gag genes remained markedly homogeneous, indicating little to undetectable virus replication. These results provide the evidence for HIV-1 infection in ES individuals below the detection limit of standard assays, suggesting that extraordinary control of infection can occur. The two HIV-infected ES individuals remained healthy and were not superinfected with other HIV-1 strains despite continued high-risk sexual exposures to multiple HIV-infected partners. Understanding the mechanisms that confer diminished replicative capacity of HIV-1 in these hosts is paramount to developing strategies for protection against and control of HIV-1 infection.

scholarly journals Diversity, Divergence, and Evolution of Cell-Free Human Immunodeficiency Virus Type 1 in Vaginal Secretions and Blood of Chronically Infected Women: Associations with Immune Status

2005 ◽  
Vol 79 (15) ◽  
pp. 9799-9809 ◽  
Author(s):  
Sharon T. Sullivan ◽  
Usha Mandava ◽  
Tammy Evans-Strickfaden ◽  
Jeffrey L. Lennox ◽  
Tedd V. Ellerbrock ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Cell Level ◽  
Immunodeficiency Virus ◽  
Vaginal Secretions ◽  
Low Levels ◽  
Changes Over Time ◽  
Hiv 1

ABSTRACT Most human immunodeficiency virus type 1 (HIV-1) infections are believed to be the result of exposure to the virus in genital secretions. However, prevention and therapeutic strategies are usually based on characterizations of HIV-1 in blood. To understand better the dynamics between HIV-1 quasispecies in the genital tract and blood, we performed heteroduplex assays on amplified env products from cell-free viral RNA in paired vaginal secretion (VS) and blood plasma (BP) samples of 14 women followed for 1.5 to 3.5 years. Diversity and divergence were less in VS than in BP (P = 0.03 and P < 0.01, respectively), and divergence at both sites was correlated with blood CD4+ cell levels (VS, P = 0.05; BP, P = 0.01). Evolution of quasispecies was observed in 58% of the women; the loss or gain of quasispecies in VS or BP was always accompanied by such changes at the other site. In addition, sustained compartmentalization of quasispecies in VS was found for four women, even as CD4+ cell levels decreased to low levels (<50 cells/μl). Quasispecies changes over time were associated with fluctuations in CD4+ cell levels; concordant increases or decreases in VS and BP divergence had greater CD4+ cell level changes than intervals with discordant changes (P = 0.05), and women with evolving quasispecies had greater decreases in CD4+ cell levels compared to that for women who maintained the same quasispecies (P < 0.05). Thus, diversity, divergence, and evolution of cell-free HIV-1 in VS can be different from that in BP, and dynamics between their respective quasispecies are associated with changes in CD4+ cell levels.

scholarly journals Single Point Mutations in the Zinc Finger Motifs of the Human Immunodeficiency Virus Type 1 Nucleocapsid Alter RNA Binding Specificities of the Gag Protein and Enhance Packaging and Infectivity

2005 ◽  
Vol 79 (12) ◽  
pp. 7756-7767 ◽  
Author(s):  
Michal Mark-Danieli ◽  
Nihay Laham ◽  
Michal Kenan-Eichler ◽  
Asher Castiel ◽  
Daniel Melamed ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Zinc Finger ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Rna Binding ◽  
Gag Protein ◽  
Encapsidation Signal ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT A specific interaction between the nucleocapsid (NC) domain of the Gag polyprotein and the RNA encapsidation signal (Ψ) is required for preferential incorporation of the retroviral genomic RNA into the assembled virion. Using the yeast three-hybrid system, we developed a genetic screen to detect human immunodeficiency virus type 1 (HIV-1) Gag mutants with altered RNA binding specificities. Specifically, we randomly mutated full-length HIV-1 Gag or its NC portion and screened the mutants for an increase in affinity for the Harvey murine sarcoma virus encapsidation signal. These screens identified several NC zinc finger mutants with altered RNA binding specificities. Furthermore, additional zinc finger mutants that also demonstrated this phenotype were made by site-directed mutagenesis. The majority of these mutants were able to produce normal virion-like particles; however, when tested in a single-cycle infection assay, some of the mutants demonstrated higher transduction efficiencies than that of wild-type Gag. In particular, the N17K mutant showed a seven- to ninefold increase in transduction, which correlated with enhanced vector RNA packaging. This mutant also packaged larger amounts of foreign RNA. Our results emphasize the importance of the NC zinc fingers, and not other Gag sequences, in achieving specificity in the genome encapsidation process. In addition, the described mutations may contribute to our understanding of HIV diversity resulting from recombination events between copackaged viral genomes and foreign RNA.

scholarly journals Functional Analysis and Structural Modeling of Human APOBEC3G Reveal the Role of Evolutionarily Conserved Elements in the Inhibition of Human Immunodeficiency Virus Type 1 Infection and Alu Transposition

2009 ◽  
Vol 83 (23) ◽  
pp. 12611-12621 ◽  
Author(s):  
Yannick Bulliard ◽  
Priscilla Turelli ◽  
Ute F. Röhrig ◽  
Vincent Zoete ◽  
Bastien Mangeat ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Large Scale ◽  
Rna Binding ◽  
Evolutionary Forces ◽  
Wide Range ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Retroelements are important evolutionary forces but can be deleterious if left uncontrolled. Members of the human APOBEC3 family of cytidine deaminases can inhibit a wide range of endogenous, as well as exogenous, retroelements. These enzymes are structurally organized in one or two domains comprising a zinc-coordinating motif. APOBEC3G contains two such domains, only the C terminal of which is endowed with editing activity, while its N-terminal counterpart binds RNA, promotes homo-oligomerization, and is necessary for packaging into human immunodeficiency virus type 1 (HIV-1) virions. Here, we performed a large-scale mutagenesis-based analysis of the APOBEC3G N terminus, testing mutants for (i) inhibition of vif-defective HIV-1 infection and Alu retrotransposition, (ii) RNA binding, and (iii) oligomerization. Furthermore, in the absence of structural information on this domain, we used homology modeling to examine the positions of functionally important residues and of residues found to be under positive selection by phylogenetic analyses of primate APOBEC3G genes. Our results reveal the importance of a predicted RNA binding dimerization interface both for packaging into HIV-1 virions and inhibition of both HIV-1 infection and Alu transposition. We further found that the HIV-1-blocking activity of APOBEC3G N-terminal mutants defective for packaging can be almost entirely rescued if their virion incorporation is forced by fusion with Vpr, indicating that the corresponding region of APOBEC3G plays little role in other aspects of its action against this pathogen. Interestingly, residues forming the APOBEC3G dimer interface are highly conserved, contrasting with the rapid evolution of two neighboring surface-exposed amino acid patches, one targeted by the Vif protein of primate lentiviruses and the other of yet-undefined function.

Sign in / Sign up

Export Citation Format

Share Document