scholarly journals Association of Nef with p21-Activated Kinase 2 Is Dispensable for Efficient Human Immunodeficiency Virus Type 1 Replication and Cytopathicity in Ex Vivo-Infected Human Lymphoid Tissue

2007 ◽  
Vol 81 (23) ◽  
pp. 13005-13014 ◽  
Author(s):  
Michael Schindler ◽  
Devi Rajan ◽  
Anke Specht ◽  
Carolin Ritter ◽  
Kati Pulkkinen ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Lymphoid Tissue ◽  
Cell Activation ◽  
Ex Vivo ◽  
Immunodeficiency Virus ◽  
Human Lymphoid Tissue ◽  
P21 Activated Kinase ◽  
Hiv 1

ABSTRACT Interaction of the human immunodeficiency virus type 1 (HIV-1) Nef protein with p21-activated kinase 2 (PAK2) has been proposed to play a role in T-cell activation, viral replication, apoptosis, and progression to AIDS. However, these hypotheses were based on results obtained using Nef mutants impaired in multiple functions. Recently, it was reported that Nef residue F191 is specifically involved in PAK2 binding. However, only a limited number of Nef activities were investigated in these studies. To further evaluate the role of F191 in Nef function and to elucidate the biological relevance of Nef-PAK2 interaction, we performed a comprehensive analysis of HIV-1 Nef mutants carrying F191H and F191R mutations. We found that the F191H mutation reduces and the F191R mutation disrupts the association of Nef with PAK2. Both mutants upregulated the major histocompatibility complex II (MHC-II)-associated invariant chain and downregulated CD4, MHC-I, and CD28, although with reduced efficiency for the latter. Furthermore, the F191H/R changes neither affected the levels of interleukin-2 receptor expression and apoptosis of HIV-1-infected primary T cells nor reduced Nef-mediated induction of NFAT. Unexpectedly, the F191H change markedly reduced and the F191R mutation disrupted the ability of Nef to enhance virion infectivity in P4-CCR5 indicator cells but not in TZM-bl cells or peripheral blood mononuclear cells. Most importantly, all HIV-1 Nef mutants replicated efficiently and caused CD4+ T-cell depletion in ex vivo-infected human lymphoid tissue. Altogether, our data show that the interaction of Nef with PAK2 does not play a major role in T-cell activation, viral replication, and apoptosis.

scholarly journals Vpr and Vpu Are Important for Efficient Human Immunodeficiency Virus Type 1 Replication and CD4+ T-Cell Depletion in Human Lymphoid Tissue Ex Vivo

2004 ◽  
Vol 78 (22) ◽  
pp. 12689-12693 ◽  
Author(s):  
Elke Rücker ◽  
Jean-Charles Grivel ◽  
Jan Münch ◽  
Frank Kirchhoff ◽  
Leonid Margolis
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cell ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Lymphoid Tissue ◽  
Ex Vivo ◽  
Immunodeficiency Virus ◽  
Human Lymphoid Tissue ◽  
Hiv 1

ABSTRACT The relevance of the accessory vpr, vpu, and nef genes for human immunodeficiency virus type 1 (HIV-1) replication in human lymphoid tissue (HLT), the major site of viral replication in vivo, is largely unknown. Here, we show that an individual deletion of nef, vpr, or vpu significantly decreases HIV-1 replication and prevents CD4+ T-cell depletion in ex vivo HLT. However, only combined defects in all three accessory genes entirely disrupt the replicative capacity of HIV-1. Our results demonstrate that nef, vpr, and vpu are all essential for efficient viral spread in HLT, suggesting an important role in AIDS pathogenesis.

scholarly journals CD4 Down-Modulation by Human Immunodeficiency Virus Type 1 Nef Correlates with the Efficiency of Viral Replication and with CD4+ T-Cell Depletion in Human Lymphoid Tissue Ex Vivo

2001 ◽  
Vol 75 (21) ◽  
pp. 10113-10117 ◽  
Author(s):  
Svetlana Glushakova ◽  
Jan Münch ◽  
Silke Carl ◽  
Thomas C. Greenough ◽  
John L. Sullivan ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cell ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Lymphoid Tissue ◽  
Ex Vivo ◽  
Immunodeficiency Virus ◽  
Human Lymphoid Tissue ◽  
Hiv 1

ABSTRACT The human immunodeficiency virus type 1 (HIV-1) Nef protein is an important virulence factor. Nef has several functions, including down-modulation of CD4 and class I major histocompatibility complex cell surface expression, enhancement of virion infectivity, and stimulation of viral replication in peripheral blood mononuclear cells. Nef also increases HIV-1 replication in human lymphoid tissue (HLT) ex vivo. We analyzed recombinant and primarynef alleles with highly divergent activity in different in vitro assays to clarify which of these Nef activities are functionally linked. Our results demonstrate that Nef activity in CD4 down-regulation correlates significantly with the efficiency of HIV-1 replication and with the severity of CD4+ T-cell depletion in HLT. In conclusion, HIV-1 Nef variants with increased activity in CD4 down-modulation would cause severe depletion of CD4+ T cells in lymphoid tissues and accelerate AIDS progression.

scholarly journals Interactions between Human Immunodeficiency Virus Type 1 and Vaccinia Virus in Human Lymphoid Tissue Ex Vivo

2007 ◽  
Vol 81 (22) ◽  
pp. 12458-12464 ◽  
Author(s):  
Christophe Vanpouille ◽  
Angélique Biancotto ◽  
Andrea Lisco ◽  
Beda Brichacek
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cell ◽  
Vaccinia Virus ◽  
Lymphoid Tissue ◽  
Ex Vivo ◽  
Productive Infection ◽  
Immunodeficiency Virus ◽  
Human Lymphoid Tissue ◽  
Hiv 1

ABSTRACT Vaccinia virus (VACV) has been attracting attention recently not only as a vector for various vaccines but also as an immunization tool against smallpox because of its potential use as a bioterrorism agent. It has become evident that in spite of a long history of studies of VACV, its tissue pathogenesis remains to be fully understood. Here, we investigated the pathogenesis of VACV and its interactions with human immunodeficiency virus type 1 (HIV-1) in the context of human lymphoid tissues. We found that ex vivo-cultured tonsillar tissue supports productive infection by the New York City Board of Health strain, the VACV strain of the Dryvax vaccine. VACV readily infected both T and non-T (B) lymphocytes and depleted cells of both of these subsets equally over a 12-day period postinfection. Among T lymphocytes, CD8+ cells are preferentially depleted in accordance with their preferential infection: the probability that a CD8+ T cell will be productively infected is almost six times higher than for a CD4+ T cell. T cells expressing CCR5 and the activation markers CD25, CD38, and HLA-DR are other major targets for infection by VACV in lymphoid tissue. As a consequence, VACV predominantly inhibits the replication of the R5SF162 phenotype of HIV-1 in coinfected tissues, as R5-tropic HIV-1 requires activated CCR5+ CD4+ cells for productive infection. Human lymphoid tissue infected ex vivo by VACV can be used to investigate interactions of VACV with other viruses, in particular HIV-1, and to evaluate various VACV vectors for the purpose of recombinant vaccine development.

scholarly journals Human Immunodeficiency Virus Type 1 Variants Resistant to First- and Second-Version Fusion Inhibitors and Cytopathic in Ex Vivo Human Lymphoid Tissue

2007 ◽  
Vol 81 (12) ◽  
pp. 6563-6572 ◽  
Author(s):  
Raghavan Chinnadurai ◽  
Devi Rajan ◽  
Jan Münch ◽  
Frank Kirchhoff
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Lymphoid Tissue ◽  
Ex Vivo ◽  
Fusion Inhibitors ◽  
Immunodeficiency Virus ◽  
Human Lymphoid Tissue ◽  
Hiv 1

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) fusion inhibitors blocking viral entry by binding the gp41 heptad repeat 1 (HR1) region offer great promise for antiretroviral therapy, and the first of these inhibitors, T20 (Fuzeon; enfuvirtide), is successfully used in the clinic. It has been reported previously that changes in the 3-amino-acid GIV motif at positions 36 to 38 of gp41 HR1 mediate resistance to T20 but usually not to second-version fusion inhibitors, such as T1249, which target an overlapping but distinct region in HR1 including a conserved hydrophobic pocket (HP). Based on the common lack of cross-resistance and the difficulty of selecting T1249-resistant HIV-1 variants, it has been suggested that the determinants of resistance to first- and second-version fusion inhibitors may be different. To further assess HIV-1 resistance to fusion inhibitors and to analyze where changes in HR1 are tolerated, we randomized 16 codons in the HR1 region, including those making contact with HR2 codons and/or encoding residues in the GIV motif and the HP. We found that changes only at positions 37I, 38V, and 40Q near the N terminus of HR1 were tolerated. The propagation of randomly gp41-mutated HIV-1 variants in the presence of T1249 allowed the effective selection of highly resistant forms, all containing changes in the IV residues. Overall, the extent of T1249 resistance was inversely correlated to viral fitness and cytopathicity. Notably, one HIV-1 mutant showing ∼10-fold-reduced susceptibility to T1249 inhibition replicated with wild type-like kinetics and caused substantial CD4+-T-cell depletion in ex vivo-infected human lymphoid tissue in the presence and absence of an inhibitor. Taken together, our results show that the GIV motif also plays a key role in resistance to second-version fusion inhibitors and suggest that some resistant HIV-1 variants may be pathogenic in vivo.

scholarly journals Proline 35 of Human Immunodeficiency Virus Type 1 (HIV-1) Vpr Regulates the Integrity of the N-Terminal Helix and the Incorporation of Vpr into Virus Particles and Supports the Replication of R5-Tropic HIV-1 in Human Lymphoid Tissue Ex Vivo

2007 ◽  
Vol 81 (17) ◽  
pp. 9572-9576 ◽  
Author(s):  
Jörg Votteler ◽  
Nicole Studtrucker ◽  
Stefan Sörgel ◽  
Jan Münch ◽  
Elke Rücker ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Lymphoid Tissue ◽  
Mutational Analysis ◽  
Ex Vivo ◽  
Immunodeficiency Virus ◽  
Human Lymphoid Tissue ◽  
Hiv 1

ABSTRACT Mutational analysis of the four conserved proline residues in human immunodeficiency virus type 1 (HIV-1) Vpr reveals that only Pro-35 is required for efficient replication of R5-tropic, but not of X4-tropic, viruses in human lymphoid tissue (HLT) cultivated ex vivo. While Vpr-mediated apoptosis and G2 cell cycle arrest, as well as the expression and subcellular localization of Vpr, were independent, the capacity for encapsidation of Vpr into budding virions was dependent on Pro-35. 1H nuclear magnetic resonance data suggest that mutation of Pro-35 causes a conformational change in the hydrophobic core of the molecule, whose integrity is required for the encapsidation of Vpr, and thus, Pro-35 supports the replication of R5-tropic HIV-1 in HLT.

scholarly journals Human Immunodeficiency Virus Type 1 Vpr Impairs Dendritic Cell Maturation and T-Cell Activation: Implications for Viral Immune Escape

2005 ◽  
Vol 79 (13) ◽  
pp. 7990-8003 ◽  
Author(s):  
Biswanath Majumder ◽  
Michelle L. Janket ◽  
Elizabeth A. Schafer ◽  
Keri Schaubert ◽  
Xiao-Li Huang ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cell ◽  
Human Immunodeficiency Virus Type ◽  
T Cell Activation ◽  
Immune Evasion ◽  
Cell Activation ◽  
Immunodeficiency Virus ◽  
Hiv 1 ◽  
Cytokine Profiling

ABSTRACT Antigen presentation and T-cell activation are dynamic processes involving signaling molecules present in both APCs and T cells. Effective APC function and T-cell activation can be compromised by viral immune evasion strategies, including those of human immunodeficiency virus type 1 (HIV-1). In this study, we determined the effects of HIV-1 Vpr on one of the initial target of the virus, dendritic cells (DC), by investigating DC maturation, cytokine profiling, and CD8-specific T-cell stimulation function followed by a second signal. Vpr impaired the expression of CD80, CD83, and CD86 at the transcriptional level without altering normal cellular transcription. Cytokine profiling indicated that the presence of Vpr inhibited production of interleukin 12 (IL-12) and upregulated IL-10, whereas IL-6 and IL-1β were unaltered. Furthermore, DC infected with HIV-1 vpr + significantly reduced the activation of antigen-specific memory and recall cytotoxic-T-lymphocyte responses. Taken together, these results indicate that HIV-1 Vpr may in part be responsible for HIV-1 immune evasion by inhibiting the maturation of costimulatory molecules and cytokines essential for immune activation.

scholarly journals Distinct Mechanisms of CD4+ and CD8+ T-Cell Activation and Bystander Apoptosis Induced by Human Immunodeficiency Virus Type 1 Virions

2005 ◽  
Vol 79 (10) ◽  
pp. 6299-6311 ◽  
Author(s):  
Geoffrey H. Holm ◽  
Dana Gabuzda
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Cell Depletion ◽  
T Cell Depletion ◽  
Hla Dr ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Apoptosis of uninfected bystander T cells contributes to T-cell depletion during human immunodeficiency virus type 1 (HIV-1) infection. HIV-1 envelope/receptor interactions and immune activation have been implicated as contributors to bystander apoptosis. To better understand the relationship between T-cell activation and bystander apoptosis during HIV-1 pathogenesis, we investigated the effects of the highly cytopathic CXCR4-tropic HIV-1 variant ELI6 on primary CD4+ and CD8+ T cells. Infection of primary T-cell cultures with ELI6 induced CD4+ T-cell depletion by direct cell lysis and bystander apoptosis. Exposure of primary CD4+ and CD8+ T cells to nonreplicating ELI6 virions induced bystander apoptosis through a Fas-independent mechanism. Bystander apoptosis of CD4+ T cells required direct contact with virions and Env/CXCR4 binding. In contrast, the apoptosis of CD8+ T cells was triggered by a soluble factor(s) secreted by CD4+ T cells. HIV-1 virions activated CD4+ and CD8+ T cells to express CD25 and HLA-DR and preferentially induced apoptosis in CD25+HLA-DR+ T cells in a CXCR4-dependent manner. Maximal levels of binding, activation, and apoptosis were induced by virions that incorporated MHC class II and B7-2 into the viral membrane. These results suggest that nonreplicating HIV-1 virions contribute to chronic immune activation and T-cell depletion during HIV-1 pathogenesis by activating CD4+ and CD8+ T cells, which then proceed to die via apoptosis. This mechanism may represent a viral immune evasion strategy to increase viral replication by activating target cells while killing immune effector cells that are not productively infected.

scholarly journals Noninfectious X4 but Not R5 Human Immunodeficiency Virus Type 1 Virions Inhibit Humoral Immune Responses in Human Lymphoid Tissue Ex Vivo

2004 ◽  
Vol 78 (13) ◽  
pp. 7061-7068 ◽  
Author(s):  
Wendy Fitzgerald ◽  
Andrew W. Sylwester ◽  
Jean-Charles Grivel ◽  
Jeffrey D. Lifson ◽  
Leonid B. Margolis
Keyword(s):  
T Cells ◽  
Immune Responses ◽  
Lymphoid Tissue ◽  
Ex Vivo ◽  
Humoral Immune ◽  
Humoral Immune Responses ◽  
Immunodeficiency Virus ◽  
Human Lymphoid Tissue ◽  
Hiv 1

ABSTRACT Ex vivo human immunodeficiency virus type 1 (HIV-1) infection of human lymphoid tissue recapitulates some aspects of in vivo HIV-1 infection, including a severe depletion of CD4+ T cells and suppression of humoral immune responses to recall antigens or to polyclonal stimuli. These effects are induced by infection with X4 HIV-1 variants, whereas infection with R5 variants results in only mild depletion of CD4+ T cells and no suppression of immune responses. To study the mechanisms of suppression of immune responses in this ex vivo system, we used aldrithiol-2 (AT-2)-inactivated virions that have functional envelope glycoproteins but are not infectious and do not deplete CD4+ T cells in human lymphoid tissues ex vivo. Nevertheless, AT-2-inactivated X4 (but not R5) HIV-1 virions, even with only a brief exposure, inhibit antibody responses in human lymphoid tissue ex vivo, similarly to infectious virus. This phenomenon is mediated by soluble immunosuppressive factor(s) secreted by tissue exposed to virus.

scholarly journals Human Immunodeficiency Virus Type 1 (HIV-1) Non-B Subtypes Are Similar to HIV-1 Subtype B in that Coreceptor Specificity Is a Determinant of Cytopathicity in Human Lymphoid Tissue Infected Ex Vivo

2001 ◽  
Vol 75 (21) ◽  
pp. 10520-10522 ◽  
Author(s):  
Nina Malkevich ◽  
Chad Womack ◽  
Punita Pandya ◽  
Jean-Charles Grivel ◽  
Anthony S. Fauci ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Lymphocytes ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Lymphoid Tissue ◽  
Ex Vivo ◽  
Immunodeficiency Virus ◽  
Human Lymphoid Tissue ◽  
Hiv 1

ABSTRACT We sought to determine the relationship between virus-mediated CD4+ T-lymphocyte cytopathicity and viral coreceptor preference among various human immunodeficiency virus type 1 (HIV-1) subtypes in an ex vivo-infected human lymphoid tissue model. Our data show that all R5 HIV-1 infections resulted in mild depletion of CD4+ T lymphocytes, whereas all X4 HIV-1 infections caused severe depletion of CD4+ T lymphocytes regardless of their subtype origin. Thus, at least for the viruses within subtypes A, B, C, and E that were tested, coreceptor specificity is a critical factor that determines the ability of HIV-1 to deplete CD4+ T cells in human lymphoid tissue infected ex vivo.

scholarly journals Costimulation of T-cell activation and virus production by B7 antigen on activated CD4+ T cells from human immunodeficiency virus type 1-infected donors

1993 ◽  
Vol 90 (23) ◽  
pp. 11094-11098 ◽  
Author(s):  
O K Haffar ◽  
M D Smithgall ◽  
J Bradshaw ◽  
B Brady ◽  
N K Damle ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cd4 T Cells ◽  
Cell Activation ◽  
Immunodeficiency Virus ◽  
T Cell Lines ◽  
Antigen Presenting ◽  
Hiv 1

Infection with the human immunodeficiency virus type 1 (HIV-1) requires T-cell activation. Recent studies have shown that interactions of the T-lymphocyte receptors CD28 and CTLA-4 with their counter receptor, B7, on antigen-presenting cells are required for optimal T-cell activation. Here we show that HIV-1 infection is associated with decreased expression of CD28 and increased expression of B7 on CD4+ T-cell lines generated from seropositive donors by alloantigen stimulation. Loss of CD28 expression was not seen on CD4+ T-cell lines from seronegative donors, but up-regulation of B7 expression was observed upon more prolonged culture. Both T-cell proliferation and interleukin 2 mRNA accumulation in HIV-1-infected cultures required costimulation with exogenous B7 because these events were blocked by CTLA4Ig, a soluble form of CTLA-4 that binds B7 with high avidity. In contrast, levels of HIV-1 RNA were not affected by CTLA4Ig, indicating that regulation of virus transcription in these cultures did not depend upon CD28-B7 engagement. Infected T cells could present alloantigen to fresh, uninfected CD4+ T cells, leading to increased proliferation and virus spread to the activated cells. Both of these events were blocked by CTLA4Ig. Thus, chronic activation of HIV-1-infected CD4+ T cells reduces expression of CD28 and increases expression of B7, thereby enabling these T cells to become antigen-presenting cells for uninfected CD4+ T cells; this might be another mechanism for HIV-1 transmission via T-cell-T-cell contact.

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