bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reovirus Infection Activates JNK and the JNK-Dependent Transcription Factor c-Jun
Authors: Clarke Penny , Meintzer Suzanne M. , Widmann Christian , Johnson Gary L. , Tyler Kenneth L. 
Published: July 2002

ABSTRACT
Viral infection often perturbs host cell signaling pathways including those involving mitogen-activated protein kinases (MAPKs). We now show that reovirus infection results in the selective activation of c-Jun N-terminal kinase (JNK). Reovirus-induced JNK activation is associated with an increase in the phosphorylation of the JNK-dependent transcription factor c-Jun. Reovirus serotype 3 prototype strains Abney (T3A) and Dearing (T3D) induce significantly more JNK activation and c-Jun phosphorylation than does the serotype 1 prototypic strain Lang (T1L). T3D and T3A also induce more apoptosis in infected cells than T1L, and there was a significant correlation between the ability of these viruses to phosphorylate c-Jun and induce apoptosis. However, reovirus-induced apoptosis, but not reovirus-induced c-Jun phosphorylation, is inhibited by blocking TRAIL/receptor binding, suggesting that apoptosis and c-Jun phosphorylation involve parallel rather than identical pathways. Strain-specific differences in JNK activation are determined by the reovirus S1 and M2 gene segments, which encode viral outer capsid proteins (ς1 and μ1c) involved in receptor binding and host cell membrane penetration. These same gene segments also determine differences in the capacity of reovirus strains to induce apoptosis, and again a significant correlation between the capacity of T1L × T3D reassortant reoviruses to both activate JNK and phosphorylate c-Jun and to induce apoptosis was shown. The extracellular signal-related kinase (ERK) is also activated in a strain-specific manner following reovirus infection. Unlike JNK activation, ERK activation could not be mapped to specific reovirus gene segments, suggesting that ERK activation and JNK activation are triggered by different events during virus-host cell interaction.
Analysis of Total Human Immunodeficiency Virus (HIV)-Specific CD4
+
and CD8
+
T-Cell Responses: Relationship to Viral Load in Untreated HIV Infection
Authors: Betts Michael R. , Ambrozak David R. , Douek Daniel C. , Bonhoeffer Sebastian , Brenchley Jason M. , Casazza Joseph P. , Koup Richard A. , Picker Louis J. 
Published: July 2002

ABSTRACT

Human immunodeficiency virus (HIV)-specific T-cell responses are thought to play a key role in viral load decline during primary infection and in determining the subsequent viral load set point. The requirements for this effect are unknown, partly because comprehensive analysis of total HIV-specific CD4
+
and CD8
+
T-cell responses to all HIV-encoded epitopes has not been accomplished. To assess these responses, we used cytokine flow cytometry and overlapping peptide pools encompassing all products of the HIV-1 genome to study total HIV-specific T-cell responses in 23 highly active antiretroviral therapy naı̈ve HIV-infected patients. HIV-specific CD8
+
T-cell responses were detectable in all patients, ranging between 1.6 and 18.4% of total CD8
+
T cells. HIV-specific CD4
+
T-cell responses were present in 21 of 23 patients, although the responses were lower (0.2 to 2.94%). Contrary to previous reports, a positive correlation was identified between the plasma viral load and the total HIV-, Env-, and Nef-specific CD8
+
T-cell frequency. No correlation was found either between viral load and total or Gag-specific CD4
+
T-cell response or between the frequency of HIV-specific CD4
+
and CD8
+
T cells. These results suggest that overall frequencies of HIV-specific T cells are not the sole determinant of immune-mediated protection in HIV-infection.
Role of Calcium in Protein Folding and Function of Tva, the Receptor of Subgroup A Avian Sarcoma and Leukosis Virus
Authors: Wang Qing-Yin , Dolmer Klavs , Huang Wen , Gettins Peter G. W. , Rong Lijun 
Published: July 2002

ABSTRACT

Tva is the cellular receptor for subgroup A avian sarcoma and leukosis virus (ASLV-A). The viral receptor function of Tva is determined by a 40-residue cysteine-rich motif called the LDL-A module. In this study, we expressed and purified the wild-type (wt) Tva LDL-A module as well as several mutants and examined their in vitro folding properties. We found that, as for other LDL-A modules, correct folding and structure of the Tva LDL-A module is Ca
2+
dependent. When calcium was present during in vitro protein folding, the wt module was eluted as a single peak by reverse-phase high-pressure liquid chromatography. Furthermore, two-dimensional nuclear magnetic resonance (NMR) spectroscopy gave well-dispersed spectra in the presence of calcium. In contrast, the same protein folded in vitro in the absence of calcium was eluted as multiple broad peaks and gave a poorly dispersed NMR spectrum in the presence of calcium. The calcium affinity (

K
d

) of the Tva LDL-A module, determined by isothermal titration calorimetry, is approximately 40 μM. Characterization of several Tva mutants provided further evidence that calcium is important in protein folding and function of Tva. Mutations of the Ca
2+
-binding residues (D46A and E47A) completely abrogated the Ca
2+
-binding ability of Tva, and the proteins were not correctly folded. Interestingly, mutations of two non-calcium-binding residues (W48A and L34A) also exerted adverse effect on Ca
2+
-dependent folding, albeit to a much less extent. Our results provide new insights regarding the structure and function of Tva in ASLV-A entry.
Reversal of Human Immunodeficiency Virus Type 1 IIIB to a Neutralization-Resistant Phenotype in an Accidentally Infected Laboratory Worker with a Progressive Clinical Course
Authors: Beaumont Tim , van Nuenen Ad , Broersen Silvia , Blattner William A. , Lukashov Vladimir V. , Schuitemaker Hanneke 
Published: July 2002

ABSTRACTThe role of humoral immunity in controlling human immunodeficiency virus type 1 (HIV-1) is still controversial. The resistance of primary HIV-1 variants to neutralization by antibodies, sera from HIV-1-infected patients, and soluble CD4 protein has been suggested to be a prerequisite for the virus to establish persistence in vivo. To further test this hypothesis, we studied the neutralization sensitivity of two IIIB/LAV variants that were isolated from a laboratory worker who accidentally was infected with the T-cell-line-adapted neutralization-sensitive IIIB isolate. Compared to the original virus in the inoculum, the reisolated viruses showed an increased resistance to neutralization over time. The ratio of nonsynonymous to synonymous nucleotide substitutions in the envelope gene pointed to strong positive selection. The emergence of neutralization-resistant HIV preceded disease development in this laboratory worker. Our results imply that the neutralization resistance of primary HIV may indeed be considered an escape mechanism from humoral immune control.
Direct In Vitro Binding of Full-Length Human Immunodeficiency Virus Type 1 Nef Protein to CD4 Cytoplasmic Domain
Authors: Preusser Andrea , Briese Lars , Baur Andreas S. , Willbold Dieter 
Published: July 2002

ABSTRACTThe Nef protein of the simian and human immunodeficiency viruses is known to directly bind and downregulate the CD4 receptor. Although the molecular mechanism is well understood, direct binding of Nef and CD4 is difficult to demonstrate and is believed to be of low affinity. Applying nuclear magnetic resonance and fluorescence spectroscopy, we biophysically reevaluated the CD4-Nef complex and found the dissociation constant to be in the submicromolar range. We conclude that additional, so far disregarded residues in the N terminus of Nef are important for interaction with CD4.
West Nile Virus Recombinant DNA Vaccine Protects Mouse and Horse from Virus Challenge and Expresses In Vitro a Noninfectious Recombinant Antigen That Can Be Used in Enzyme-Linked Immunosorbent Assays
Authors: Davis Brent S. , Chang Gwong-Jen J. , Cropp Bruce , Roehrig John T. , Martin Denise A. , Mitchell Carl J. , Bowen Richard , Bunning Michel L. 
Published: July 2002

ABSTRACTIntroduction of West Nile (WN) virus into the United States in 1999 created major human and animal health concerns. Currently, no human or veterinary vaccine is available to prevent WN viral infection, and mosquito control is the only practical strategy to combat the spread of disease. Starting with a previously designed eukaryotic expression vector, we constructed a recombinant plasmid (pCBWN) that expressed the WN virus prM and E proteins. A single intramuscular injection of pCBWN DNA induced protective immunity, preventing WN virus infection in mice and horses. Recombinant plasmid-transformed COS-1 cells expressed and secreted high levels of WN virus prM and E proteins into the culture medium. The medium was treated with polyethylene glycol to concentrate proteins. The resultant, containing high-titered recombinant WN virus antigen, proved to be an excellent alternative to the more traditional suckling-mouse brain WN virus antigen used in the immunoglobulin M (IgM) antibody-capture and indirect IgG enzyme-linked immunosorbent assays. This recombinant antigen has great potential to become the antigen of choice and will facilitate the standardization of reagents and implementation of WN virus surveillance in the United States and elsewhere.
The LD78β Isoform of MIP-1α Is the Most Potent CC-Chemokine in Inhibiting CCR5-Dependent Human Immunodeficiency Virus Type 1 Replication in Human Macrophages
Authors: Aquaro Stefano , Menten Patricia , Struyf Sofie , Proost Paul , Van Damme Jo , De Clercq Erik , Schols Dominique 
Published: July 2002

ABSTRACTThe CC-chemokines RANTES, macrophage inflammatory protein 1α (MIP-1α), and MIP-1β are natural ligands for the CC-chemokine receptor CCR5. MIP-1α, also known as LD78α, has an isoform, LD78β, which was identified as the product of a nonallelic gene. The two isoforms differ in only 3 amino acids. LD78β was recently reported to be a much more potent CCR5 agonist than LD78α and RANTES in inducing intracellular Ca2+signaling and chemotaxis. CCR5 is expressed by human monocytes/macrophages (M/M) and represents an important coreceptor for macrophage-tropic, CCR5-using (R5) human immunodeficiency virus type 1 (HIV-1) strains to infect the cells. We compared the antiviral activities of LD78β and the other CC-chemokines in M/M. LD78β at 100 ng/ml almost completely blocked HIV-1 replication, while at the same concentration LD78α had only weak antiviral activity. Moreover, when HIV-1 infection in M/M was monitored by a flow cytometric analysis using p24 antigen intracellular staining, LD78β proved to be the most antivirally active of the chemokines. RANTES, once described as the most potent chemokine in inhibiting R5 HIV-1 infection, was found to be considerably less active than LD78β. LD78β strongly downregulated CCR5 expression in M/M, thereby explaining its potent antiviral activity.
Envelope Glycoprotein Cytoplasmic Domains from Diverse Lentiviruses Interact with the Prenylated Rab Acceptor
Authors: Evans David T. , Tillman Karl C. , Desrosiers Ronald C. 
Published: July 2002

ABSTRACTLentivirus envelope glycoproteins have unusually long cytoplasmic domains compared to those of other retroviruses. To identify cellular binding partners of the simian immunodeficiency virus (SIV) envelope transmembrane protein (gp41) cytoplasmic domain (CD), we performed a yeast two-hybrid screen of a phytohemagglutinin-activated human T-cell cDNA library with the SIV gp41 CD. The majority of positive clones (50 of 54) encoded the prenylated Rab acceptor (PRA1). PRA1 is a 21-kDa protein associated with Golgi membranes that binds to prenylated Rab proteins in their GTP-bound state. While the cellular function of PRA1 is presently unknown, this protein appears to participate in intracellular vesicular trafficking, based on its cellular localization and ability to bind multiple members of the Rab protein family. Mammalian two-hybrid assays confirmed the interaction between the SIV gp41 CD and PRA1. Furthermore, gp41 sequences important for PRA1 binding were mapped to a central leucine-rich, amphipathic α-helix in the SIV gp41 cytoplasmic tail. Although the human immunodeficiency virus (HIV-1) gp41 CD failed to interact with PRA1 in the yeast two-hybrid system, its interaction with PRA1 was significantly better than that of the SIV gp41 CD in mammalian two-hybrid assays. Interestingly, PRA1 also interacted with the Env CDs of HIV-2, bovine immunodeficiency virus, equine infectious anemia virus, and feline immunodeficiency virus. Thus, PRA1 associates with envelope glycoproteins from widely divergent lentiviruses.
Human Immunodeficiency Virus Type 1 Uses Lipid Raft-Colocalized CD4 and Chemokine Receptors for Productive Entry into CD4
+
T Cells
Authors: Popik Waldemar , Alce Timothy M. , Au Wei-Chun 
Published: July 2002

ABSTRACT

In this report, we describe a crucial role of lipid raft-colocalized receptors in the entry of human immunodeficiency virus type 1 (HIV-1) into CD4
+
T cells. We show that biochemically isolated detergent-resistant fractions have characteristics of lipid rafts. Lipid raft integrity was required for productive HIV-1 entry as determined by (i) semiquantitative PCR analysis and (ii) single-cycle infectivity assay using HIV-1 expressing the luciferase reporter gene and pseudotyped with HIV-1 HXB2 envelope or vesicular stomatitis virus envelope glycoprotein (VSV-G). Depletion of plasma membrane cholesterol with
methyl
-β-cyclodextrin (MβCD) relocalized raft-resident markers to a nonraft environment but did not significantly change the surface expression of HIV-1 receptors. MβCD treatment inhibited productive infection of HIV-1 by 95% as determined by luciferase activity in cells infected with HXB2 envelope-pseudotyped virus. In contrast, infection with VSV-G-pseudotyped virus, which enters the cells through an endocytic pathway, was not suppressed. Biochemical fractionation and confocal imaging of HIV-1 receptor distribution in live cells demonstrated that CD4, CCR5, and CXCR4 colocalized with raft-resident markers, ganglioside GM1, and glycosylphosphatidylinositol-anchored CD48. While confocal microscopy analysis revealed that HIV-1 receptors localized most likely to the same lipid microdomains, sucrose gradient analysis of the receptor localization showed that, in contrast to CD4 and CCR5, CXCR4 was associated preferentially with the nonraft membrane fraction. The binding of HIV-1 envelope gp120 to lipid rafts in the presence, but not in the absence, of cholesterol strongly supports our hypothesis that raft-colocalized receptors are directly involved in virus entry. Dramatic changes in lipid raft and HIV-1 receptor redistribution were observed upon binding of HIV-1 NL4-3 to PM1 T cells. Colocalization of CCR5 with GM1 and gp120 upon engagement of CD4 and CXCR4 by HIV-1 further supports our observation that HIV-1 receptors localize to the same lipid rafts in PM1 T cells.
Functional Evaluation of DC-SIGN Monoclonal Antibodies Reveals DC-SIGN Interactions with ICAM-3 Do Not Promote Human Immunodeficiency Virus Type 1 Transmission
Authors: Wu Li , Martin Thomas D. , Vazeux Rosemay , Unutmaz Derya , KewalRamani Vineet N. 
Published: July 2002

ABSTRACT

DC-SIGN, a type II membrane-spanning C-type lectin that is expressed on the surface of dendritic cells (DC), captures and promotes human and simian immunodeficiency virus (HIV and SIV) infection of CD4
+
T cells in
trans
. To better understand the mechanism of DC-SIGN-mediated virus transmission, we generated and functionally evaluated a panel of seven monoclonal antibodies (MAbs) against DC-SIGN family molecules. Six of the MAbs reacted with myeloid-lineage DC, whereas one MAb preferentially bound DC-SIGNR/L-SIGN, a homolog of DC-SIGN. Characterization of hematopoietic cells also revealed that stimulation of monocytes with interleukin-4 (IL-4) or IL-13 was sufficient to induce expression of DC-SIGN. All DC-SIGN-reactive MAbs competed with intercellular adhesion molecule 3 (ICAM-3) for adhesion to DC-SIGN and blocked HIV-1 transmission to T cells that was mediated by THP-1 cells expressing DC-SIGN. Similar but less efficient MAb blocking of DC-mediated HIV-1 transmission was observed, indicating that HIV-1 transmission to target cells via DC may not be dependent solely on DC-SIGN. Attempts to neutralize DC-SIGN capture and transmission of HIV-1 with soluble ICAM-3 prophylaxis were limited in success, with a maximal inhibition of 60%. In addition, disrupting DC-SIGN/ICAM-3 interactions between cells with MAbs did not impair DC-SIGN-mediated HIV-1 transmission. Finally, forced expression of ICAM-3 on target cells did not increase their susceptibility to HIV-1 transmission mediated by DC-SIGN. While these findings do not discount the role of intercellular contact in facilitating HIV-1 transmission, our in vitro data indicate that DC-SIGN interactions with ICAM-3 do not promote DC-SIGN-mediated virus transmission.
C-Type Lectins DC-SIGN and L-SIGN Mediate Cellular Entry by Ebola Virus in
cis
and in
trans
Authors: Alvarez Carmen P. , Lasala Fátima , Carrillo Jaime , Muñiz Oscar , Corbí Angel L. , Delgado Rafael 
Published: July 2002

ABSTRACT

Ebola virus is a highly lethal pathogen responsible for several outbreaks of hemorrhagic fever. Here we show that the primate lentiviral binding C-type lectins DC-SIGN and L-SIGN act as cofactors for cellular entry by Ebola virus. Furthermore, DC-SIGN on the surface of dendritic cells is able to function as a
trans
receptor, binding Ebola virus-pseudotyped lentiviral particles and transmitting infection to susceptible cells. Our data underscore a role for DC-SIGN and L-SIGN in the infective process and pathogenicity of Ebola virus infection.
Induction of Mucosal Protection against Primary, Heterologous Simian Immunodeficiency Virus by a DNA Vaccine
Authors: Fuller Deborah Heydenburg , Rajakumar Premeela A. , Wilson Lawrence A. , Trichel Anita M. , Fuller James T. , Shipley Tim , Wu Mary S. , Weis Kathleen , Rinaldo Charles R. , Haynes Joel R. , Murphey-Corb Michael 
Published: July 2002

ABSTRACTAn effective vaccine against human immunodeficiency virus (HIV) should protect against mucosal transmission of genetically divergent isolates. As a safe alternative to live attenuated vaccines, the immunogenicity and protective efficacy of a DNA vaccine containing simian immunodeficiency virus (SIV) strain 17E-Fr (SIV/17E-Fr)gag-pol-envwas analyzed in rhesus macaques. Significant levels of cytotoxic T lymphocytes (CTL), but low to undetectable serum antibody responses, were observed following multiple immunizations. SIV-specific mucosal antibodies and CTL were also detected in rectal washes and gut-associated lymphoid tissues, respectively. Vaccinated and naive control monkeys were challenged intrarectally with SIV strain DeltaB670 (SIV/DeltaB670), a primary isolate whoseenvis 15% dissimilar to that of the vaccine strain. Four of seven vaccinees were protected from infection as determined by the inability to identify viral RNA or DNA sequences in the peripheral blood and the absence of anamnestic antibody responses postchallenge. This is the first report of mucosal protection against a primary pathogenic, heterologous isolate of SIV by using a commercially viable vaccine approach. These results support further development of a DNA vaccine for protection against HIV.
Adeno-Associated Virus Capsids Displaying Immunoglobulin-Binding Domains Permit Antibody-Mediated Vector Retargeting to Specific Cell Surface Receptors
Authors: Ried Martin U. , Girod Anne , Leike Kristin , Büning Hildegard , Hallek Michael 
Published: July 2002

ABSTRACT

Recombinant adeno-associated virus type 2 (rAAV2) is a promising vector for human somatic gene therapy. However, its broad host range is a disadvantage for some applications, because it reduces the specificity of the gene transfer. To overcome this limitation, we sought to create a versatile rAAV vector targeting system which would allow us to redirect rAAV binding to specific cell surface receptors by simple coupling of different ligands to its capsid. For this purpose, an immunoglobulin G (IgG) binding domain of protein A, Z34C, was inserted into the AAV2 capsid at amino acid position 587. The resulting AAV2-Z34C mutants could be packaged and purified to high titers and bound to IgG molecules. rAAV2-Z34C vectors coupled to antibodies against CD29 (β
1
-integrin), CD117 (c-kit receptor), and CXCR4 specifically transduced distinct human hematopoietic cell lines. In marked contrast, no transduction was seen in the absence of antibodies or in the presence of specific blocking reagents. These results demonstrate for the first time that an immunoglobulin binding domain can be inserted into the AAV2 capsid and coupled to various antibodies, which mediate the retargeting of rAAV vectors to specific cell surface receptors.
Differential Activation of Innate Immune Responses by Adenovirus and Adeno-Associated Virus Vectors
Authors: Zaiss Anne-Kathrin , Liu Qiang , Bowen Gloria P. , Wong Norman C. W. , Bartlett Jeffrey S. , Muruve Daniel A. 
Published: July 2002

ABSTRACTAdenovirus vectors induce acute inflammation of infected tissues due to activation of the innate immune system and expression of numerous chemokines and cytokines in transduced target cells. In contrast, adeno-associated virus (AAV) vectors are not associated with significant inflammation experimentally or clinically. We tested the ability of AAV vectors to induce the expression of chemokines in vitro and to activate the innate immune system in vivo. In human HeLa cells and murine renal epithelium-derived cells (REC cells) the adenovirus vector AdlacZ induced the expression of multiple inflammatory chemokines including RANTES, interferon-inducible protein 10 (IP-10), interleukin-8 (IL-8), MIP-1β, and MIP-2 in a dose-dependent manner. The use of AAVlacZ did not induce the expression of these chemokines above baseline levels despite 40-fold-greater titers than AdlacZ and greater amounts of intracellular AAVlacZ genomes according to Southern and slot blot analysis. This finding confirmed that the lack of AAVlacZ induction of chemokine was not due to reduced transduction. In DBA/2 mice, the intravenous administration of 2.5 × 1011particles of AAVlacZ resulted in the rapid induction of liver tumor necrosis factor alpha (TNF-α), RANTES, IP-10, MIP-1β, MCP-1, and MIP-2 mRNAs. However, 6 h following injection, chemokine mRNA levels returned to baseline. As expected, administration of 10-fold less AdlacZ caused an induction of liver TNF-α and chemokine mRNAs that persisted for more than 24 h posttransduction. Whereas intravenous administration of 2.5 × 1011particles of AAVlacZ triggered a transient infiltration of neutrophils and CD11b+cells into liver, this response stood in contrast to widespread inflammation and toxicity induced by AdlacZ. Kupffer cell depletion abolished AAVlacZ but not AdlacZ-induced chemokine expression and neutrophil infiltration. In summary, these results show that AAV vectors activate the innate immune system to a lesser extent than do adenovirus vectors and offer a possible explanation for the reduced inflammatory properties of AAV compared to adenovirus vectors.