bluuebunny/crossref_metadata_2025_split huggingface dataset:
DNA Replication Efficiency Depends on Transcription Factor-Binding Sites
Authors: Turner William J. , Woodworth Mary E. 
Published: July 2002

ABSTRACT

Naturally arising variants of simian virus 40 (SV40), generated by serial passage of the virus at high multiplicities of infection, provide important insight into the role of transcription factor-binding sites in enhancing DNA replication. Although the variants that arise from numerous recombination events are the result of selective pressure to replicate more efficiently than the other variants in the infection, there is no transcription pressure. Therefore, it is interesting that a minimum of two viral Sp1 transcription factor-binding sites are retained and that host AP-1 and NF-1 transcription factor-binding sites are incorporated into the 100-bp regulatory region that maximizes DNA replication in these variants. We cotransfected COS-1 cells (that provide viral large T antigen for DNA replication) to examine the effect of transcription factor-binding sites on the replication of plasmid constructs that contain the SV40 origin of replication (
ori
). The level of relative replication efficiency (RRE) depends on the number and type of transcription factor-binding sites. Replication increases as the number of transcription factor-binding sites increases within the regulatory region of the variants; AP-1 sites are more effective than NF-1 transcription factor-binding sites. Competition between constructs in transfections magnifies the difference in their RREs. The results indicate that transcription factor-binding sites play an important role in enhancing DNA replication.
Identification of a Novel Transcriptional Repressor Encoded by Human Cytomegalovirus
Authors: LaPierre Lorie A. , Biegalke Bonita J. 
Published: July 2002

ABSTRACT
The expression of human cytomegalovirus (HCMV) genes during viral replication is precisely regulated, with the interactions of both transcriptional activators and repressors determining the level of gene expression. One gene of HCMV, the US3 gene, is transcriptionally repressed early in infection. Repression of US3 expression requires viral infection and protein synthesis and is mediated through a DNA sequence, the transcriptional repressive element. In this report, we identify the protein that represses US3 transcription as the product of the HCMV UL34 open reading frame. The protein encoded by UL34 (pUL34) binds to the US3 transcriptional repressive element in yeast and in vitro. pUL34 localizes to the nucleus and alone is sufficient for repression of US3 expression. The data presented here, along with earlier data (B. J. Biegalke, J. Virol. 72:5457–5463, 1998), suggests that pUL34 binding of the transcriptional repressive element prevents transcription initiation complex formation.
Free Major Histocompatibility Complex Class I Heavy Chain Is Preferentially Targeted for Degradation by Human T-Cell Leukemia/Lymphotropic Virus Type 1 p12IProtein
Authors: Johnson Julie M. , Nicot Christophe , Fullen Jake , Ciminale Vincenzo , Casareto Luca , Mulloy James C. , Jacobson Steve , Franchini Genoveffa 
Published: July 2002

ABSTRACTHuman T-cell leukemia virus type 1 (HTLV-1) establishes a persistent infection in the host despite a vigorous virus-specific immune response. Here we demonstrate that an HTLV-1-encoded protein, p12I, resides in the endoplasmic reticulum (ER) and Golgi and physically binds to the free human major histocompatibility complex class I heavy chains (MHC-I-Hc) encoded by the HLA-A2, -B7, and -Cw4 alleles. As a result of this interaction, the newly synthesized MHC-I-Hc fails to associate with β2-microglobulin and is retrotranslocated to the cytosol, where it is degraded by the proteasome complex. Targeting of the free MHC-I-Hc, and not the MHC-I-Hc–β2-microglobulin complex, by p12Irepresents a novel mechanism of viral interference and disrupts the intracellular trafficking of MHC-I, which results in a significant decrease in surface levels of MHC-I on human T-cells. These findings suggest that the interaction of p12Iwith MHC-1-Hc may interfere with antigen presentation in vivo and facilitate escape of HTLV-1-infected cells from immune recognition.
Efficacy of Dideoxynucleosides against Human Foamy Virus and Relationship to Its Reverse Transcriptase Amino Acid Sequence and Structure
Authors: Yvon-Groussin Anne , Mugnier Pierre , Bertin Philippe , Grandadam Marc , Agut Henri , Huraux Jean Marie , Calvez Vincent 
Published: July 2002

ABSTRACTHuman foamy virus (HFV), a retrovirus of simian origin which occasionally infects humans, is the basis of retroviral vectors in development for gene therapy. Clinical considerations of how to treat patients developing an uncontrolled infection by either HFV or HFV-based vectors need to be raised. We determined the susceptibility of the HFV to dideoxynucleosides and found that only zidovudine was equally efficient against the replication of human immunodeficiency virus type 1 (HIV-1) and HFV. By contrast, zalcitabine (ddC), lamivudine (3TC), stavudine (d4T), and didanosine (ddI) were 3-, 3-, 30-, and 46-fold less efficient against HFV than against HIV-1, respectively. Some amino acid residues known to be involved in HIV-1 resistance to ddC, 3TC, d4T, and ddI were found at homologous positions of HFV reverse transcriptase (RT). These critical amino acids are located at the same positions in the three-dimensional structure of HIV-1 and HFV RT, suggesting that both enzymes share common patterns of inhibition.
Protection against Simian Immunodeficiency Virus Vaginal Challenge by Using Sabin Poliovirus Vectors
Authors: Crotty Shane , Miller Christopher J. , Lohman Barbara L. , Neagu Martha R. , Compton Lara , Lu Ding , Lü Fabien X.-S. , Fritts Linda , Lifson Jeffrey D. , Andino Raul 
Published: July 2002

ABSTRACTHere we provide the first report of protection against a vaginal challenge with a highly virulent simian immunodeficiency virus (SIV) by using a vaccine vector. New poliovirus vectors based on Sabin 1 and 2 vaccine strain viruses were constructed, and these vectors were used to generate a series of new viruses containing SIVgag,pol,env,nef, andtatin overlapping fragments. Two cocktails of 20 transgenic polioviruses (SabRV1-SIV and SabRV2-SIV) were inoculated into seven cynomolgus macaques. All monkeys produced substantial anti-SIV serum and mucosal antibody responses. SIV-specific cytotoxic T-lymphocyte responses were detected in three of seven monkeys after vaccination. All 7 vaccinated macaques, as well as 12 control macaques, were challenged vaginally with pathogenic SIVmac251. Strikingly, four of the seven vaccinated animals exhibited substantial protection against the vaginal SIV challenge. All 12 control monkeys became SIV positive. In two of the seven SabRV-SIV-vaccinated monkeys we found no virological evidence of infection following challenge, indicating that these two monkeys were completely protected. Two additional SabRV-SIV-vaccinated monkeys exhibited a pronounced reduction in postacute viremia to <103copies/ml, suggesting that the vaccine elicited an effective cellular immune response. Three of six control animals developed clinical AIDS by 48 weeks postchallenge. In contrast, all seven vaccinated monkeys remained healthy as judged by all clinical parameters. These results demonstrate the efficacy of SabRV as a potential human vaccine vector, and they show that the use of a vaccine vector cocktail expressing an array of defined antigenic sequences can be an effective vaccination strategy in an outbred population.
Antibody-Directed Targeting of Retroviral Vectors via Cell Surface Antigens
Authors: Morizono Kouki , Bristol Gregory , Xie Yi-ming , Kung Sam Kam-Pun , Chen Irvin S. Y. 
Published: July 2002

ABSTRACT
Targeted stable transduction of specific cells is a highly desirable goal for gene therapy applications. We report an efficient and broadly applicable approach for targeting retroviral vectors to specific cells. We find that the envelope of the alphavirus Sindbis virus can pseudotype human immunodeficiency virus type 1- and murine leukemia virus-based retroviral vectors. When modified to contain the Fc-binding domain of protein A, this envelope gives a significant enhancement in specificity in combination with antibodies specific for HLA and CD4 relative to that without antibody. Unlike previous targeting strategies for retroviral transduction, the virus titers are relatively high and stable and can be further increased by ultracentrifugation. This study provides proof of principle for a targeting strategy that would be generally useful for many gene therapy applications.
A Preponderance of CCR5+CXCR4+Mononuclear Cells Enhances Gastrointestinal Mucosal Susceptibility to Human Immunodeficiency Virus Type 1 Infection
Authors: Poles Michael A. , Elliott Julie , Taing Philip , Anton Peter A. , Chen Irvin S. Y. 
Published: July 2002

ABSTRACTThe gastrointestinal mucosa harbors the majority of the body's CD4+cells and appears to be uniquely susceptible to human immunodeficiency virus type 1 (HIV-1) infection. We undertook this study to examine the role of differences in chemokine receptor expression on infection of mucosal mononuclear cells (MMCs) and peripheral blood mononuclear cells (PBMCs) by R5- and X4-tropic HIV-1. We performed in vitro infections of MMCs and PBMCs with R5- and X4-tropic HIV-1, engineered to express murine CD24 on the infected cell's surface, allowing for quantification of HIV-infected cells and their phenotypic characterization. A greater percentage of MMCs than PBMCs are infected by both R5- and X4-tropic HIV-1. Significant differences exist in terms of chemokine receptor expression in the blood and gastrointestinal mucosa; mucosal cells are predominantly CCR5+CXCR4+, while these cells make up less than 20% of the peripheral blood cells. It is this cell population that is most susceptible to infection with both R5- and X4-tropic HIV-1 in both compartments. Regardless of whether viral isolates were derived from the blood or mucosa of HIV-1-infected patients, HIV-1 p24 production was greater in MMCs than in PBMCs. Further, the chemokine receptor tropism of these patient-derived viral isolates did not differ between compartments. We conclude that, based on these findings, the gastrointestinal mucosa represents a favored target for HIV-1, in part due to its large population of CXCR4+CCR5+target cells and not to differences in the virus that it contains.
Evidence for Early Local Viral Replication and Local Production of Antiviral Immunity upon Mucosal Simian-Human Immunodeficiency Virus SHIV
89.6
Infection in
Macaca nemestrina
Authors: Ambrose Zandrea , Larsen Kay , Thompson Jannelle , Stevens Yvonne , Finn Eric , Hu Shiu-Lok , Bosch Marnix L. 
Published: July 2002

ABSTRACT

Transmission of human immunodeficiency virus type 1 (HIV-1) is largely a result of heterosexual exposure, leading many investigators to evaluate mucosal vaccines for protection against intravaginal (i.vag.) transmission in macaque models of AIDS. Relatively little is known, however, about the dynamics of viral replication and the ensuing immune response following mucosal infection. We have utilized a simian-human immunodeficiency virus (SHIV) to study the differences in viremia, CD4 T-cell percentages, and mucosal and systemic anti-SHIV humoral and cellular immune responses during primary infection of animals infected either intravenously (i.v.) or i.vag. Positive viral cocultures, peripheral blood mononuclear cell viral load peaks, and CD4 cell declines were delayed by 1 week in the i.vag. inoculated animals compared to the animals infected i.v., demonstrating delayed viral spreading to the periphery. In contrast, mucosal anti-SHIV antibody levels were greater in magnitude and arose more rapidly and mucosal CD8
+
T-cell responses were enhanced in the i.vag. group animals, whereas both the magnitudes and times of onset of systemic immune responses for the animals in the two groups did not differ. These observations demonstrate that compartmentalization of viral replication and induction of local antiviral immunity occur in the genital tract early after i.vag. but not i.v. inoculation. Induction of mucosal immunity to target this local, contained replication should be a goal in HIV vaccine development.
Induction of Potent Immune Responses by Cationic Microparticles with Adsorbed Human Immunodeficiency Virus DNA Vaccines
Authors: O'Hagan Derek , Singh Manmohan , Ugozzoli Mildred , Wild Carl , Barnett Susan , Chen Minchao , Schaefer Mary , Doe Barbara , Otten Gillis R. , Ulmer Jeffrey B. 
Published: July 2002

ABSTRACTThe effectiveness of cationic microparticles with adsorbed DNA at inducing immune responses was investigated in mice, guinea pigs, and rhesus macaques. Plasmid DNA vaccines encoding human immunodeficiency virus (HIV) Gag and Env adsorbed onto the surface of cationic poly(lactide-coglycolide) (PLG) microparticles were shown to be substantially more potent than corresponding naked DNA vaccines. In mice immunized with HIVgagDNA, adsorption onto PLG increased CD8+T-cell and antibody responses by ∼100- and ∼1,000-fold, respectively. In guinea pigs immunized with HIVenvDNA adsorbed onto PLG, antibody responses showed a more rapid onset and achieved markedly higher enzyme-linked immunosorbent assay and neutralizing titers than in animals immunized with naked DNA. Further enhancement of antibody responses was observed in animals vaccinated with PLG/DNA microparticles formulated with aluminum phosphate. The magnitude of anti-Env antibody responses induced by PLG/DNA particles was equivalent to that induced by recombinant gp120 protein formulated with a strong adjuvant, MF-59. In guinea pigs immunized with a combination vaccine containing HIVenvand HIVgagDNA plasmids on PLG microparticles, substantially superior antibody responses were induced against both components, as measured by onset, duration, and titer. Furthermore, PLG formulation overcame an apparent hyporesponsiveness of theenvDNA component in the combination vaccine. Finally, preliminary data in rhesus macaques demonstrated a substantial enhancement of immune responses afforded by PLG/DNA. Therefore, formulation of DNA vaccines by adsorption onto PLG microparticles is a powerful means of increasing vaccine potency.
Herpes Simplex Virus Triggers and Then Disarms a Host Antiviral Response
Authors: Mossman Karen L. , Macgregor Pascale F. , Rozmus Jacob J. , Goryachev Andrew B. , Edwards Aled M. , Smiley James R. 
Published: July 2002

ABSTRACT
Virus infection induces an antiviral response that is predominantly associated with the synthesis and secretion of soluble interferon. Here, we report that herpes simplex virus type 1 virions induce an interferon-independent antiviral state in human embryonic lung cells that prevents plaquing of a variety of viruses. Microarray analysis of 19,000 human expressed sequence tags revealed induction of a limited set of host genes, the majority of which are also induced by interferon. Genes implicated in controlling the intracellular spread of virus and eliminating virally infected cells were among those induced. Induction of the cellular response occurred in the absence of de novo cellular protein synthesis and required viral penetration. In addition, this response was only seen when viral gene expression was inhibited, suggesting that a newly synthesized viral protein(s) may function as an inhibitor of this response.
Direct Activation of Innate and Antigen-Presenting Functions of Microglia following Infection with Theiler's Virus
Authors: Olson Julie K. , Girvin Ann M. , Miller Stephen D. 
Published: July 2002

ABSTRACTMicroglia are resident central nervous system (CNS) macrophages. Theiler's murine encephalomyelitis virus (TMEV) infection of SJL/J mice causes persistent infection of CNS microglia, leading to the development of a chronic-progressive CD4+T-cell-mediated autoimmune demyelinating disease. We asked if TMEV infection of microglia activates their innate immune functions and/or activates their ability to serve as antigen-presenting cells for activation of T-cell responses to virus and endogenous myelin epitopes. The results indicate that microglia lines can be persistently infected with TMEV and that infection significantly upregulates the expression of cytokines involved in innate immunity (tumor necrosis factor alpha, interleukin-6 [IL-6], IL-18, and, most importantly, type I interferons) along with upregulation of major histocompatibility complex class II, IL-12, and various costimulatory molecules (B7-1, B7-2, CD40, and ICAM-1). Most significantly, TMEV-infected microglia were able to efficiently process and present both endogenous virus epitopes and exogenous myelin epitopes to inflammatory CD4+Th1 cells. Thus, TMEV infection of microglia activates these cells to initiate an innate immune response which may lead to the activation of naive and memory virus- and myelin-specific adaptive immune responses within the CNS.
Deletion of β-Strand and α-Helix Secondary Structure in Normal Prion Protein Inhibits Formation of Its Protease-Resistant Isoform
Authors: Vorberg Ina , Chan Kaman , Priola Suzette A. 
Published: July 2002

ABSTRACT

A fundamental event in the pathogenesis of transmissible spongiform encephalopathies (TSE) is the conversion of a normal, proteinase K-sensitive, host-encoded protein, PrP-sen, into its protease-resistant isoform, PrP-res. During the formation of PrP-res, PrP-sen undergoes conformational changes that involve an increase of β-sheet secondary structure. While previous studies in which PrP-sen deletion mutants were expressed in transgenic mice or scrapie-infected cell cultures have identified regions in PrP-sen that are important in the formation of PrP-res, the exact role of PrP-sen secondary structures in the conformational transition of PrP-sen to PrP-res has not yet been defined. We constructed PrP-sen mutants with deletions of the first β-strand, the second β-strand, or the first α-helix and tested whether these mutants could be converted to PrP-res in both scrapie-infected neuroblastoma cells (Sc
+
-MNB cells) and a cell-free conversion assay. Removal of the second β-strand or the first α-helix significantly altered both processing and the cellular localization of PrP-sen, while deletion of the first β-strand had no effect on these events. However, all of the mutants significantly inhibited the formation of PrP-res in Sc
+
-MNB cells and had a greatly reduced ability to form protease-resistant PrP in a cell-free assay system. Thus, our results demonstrate that deletion of the β-strands and the first α-helix of PrP-sen can fundamentally affect PrP-res formation and/or PrP-sen processing.
Effects of Deletion and Overexpression of the
Autographa californica
Nuclear Polyhedrosis Virus
FP25K
Gene on Synthesis of Two Occlusion-Derived Virus Envelope Proteins and Their Transport into Virus-Induced Intranuclear Membranes
Authors: Rosas-Acosta Germán , Braunagel Sharon C. , Summers Max D. 
Published: July 2002

ABSTRACT

Partial deletions within
Autographa californica
open reading frame 61 (
FP25K
) alter the expression and accumulation profile of several viral proteins and the transport of occlusion-derived virus (ODV)-E66 to intranuclear membranes during infection (S. C. Braunagel et al., J. Virol. 73:8559–8570, 1999). Here we show the effects of a full deletion and overexpression of FP25K on the transport and expression of two ODV envelope proteins, ODV-E66 (E66) and ODV-E25 (E25). Deletion and overexpression of FP25K substantially altered the levels of expression of E66 during infection. Compared with cells infected with wild-type (wt) virus, the levels of E66 were reduced fivefold in cells infected with a viral mutant lacking FP25K (ΔFP25K) and were slightly increased in cells infected with a viral mutant overexpressing FP25K (FP25K
polh
). In contrast, no significant changes were observed in the levels of E25 among wt-, ΔFP25K-, and FP25K
polh
-infected cells. The changes observed in the levels of E66 among the different viral mutants were not accompanied by changes in either the time of synthesis, membrane association, protein turnover, or steady-state transcript abundance. Deletion of FP25K also substantially altered the transport and localization of E66 during infection. In cells infected with the ΔFP25K mutant virus, E66 accumulated in localized regions at the nuclear periphery and the outer nuclear membrane and did not traffic to intranuclear membranes. In contrast, in cells infected with the FP25K
polh
mutant virus E66 trafficked to intranuclear membranes. For comparison, E25 was normally transported to intranuclear membranes in both ΔFP25K- and FP25K
polh
-infected cells. Altogether these studies suggest that FP25K affects the synthesis of E66 at a posttranscriptional level, probably by altering the translation of E66; additionally, the block in transport of E66 at the nuclear envelope in ΔFP25K-infected cells suggests that the pathway of E66 trafficking to the inner nuclear membrane and intranuclear microvesicles is specifically regulated and must be influenced by factors that do not control the traffic of E25.
C-Terminal Domain of the Epstein-Barr Virus LMP2A Membrane Protein Contains a Clustering Signal
Authors: Matskova Liudmila , Ernberg Ingemar , Pawson Tony , Winberg Gösta 
Published: July 2002

ABSTRACT

The latency-regulated transmembrane protein LMP2A interferes with signaling from the B-cell antigen receptor by recruiting the tyrosine kinases Lyn and Syk and by targeting them for degradation by binding the cellular E3 ubiquitin ligase AIP4. It has been hypothesized that this constitutive activity of LMP2A requires clustering in the membrane, but molecular evidence for this has been lacking. In the present study we show that LMP2A coclusters with chimeric rat CD2 transmembrane molecules carrying the 27-amino-acid (aa) intracellular C terminus of LMP2A and that this C-terminal domain fused to the glutathione-
S
-transferase protein associates with LMP2A in cell lysates. This molecular association requires neither the cysteine-rich region between aa 471 and 480 nor the terminal three aa 495 to 497. We also show that the juxtamembrane cysteine repeats in the LMP2A C terminus are the major targets for palmitoylation but that this acylation is not required for targeting of LMP2A to detergent-insoluble glycolipid-enriched membrane microdomains.
Human Cytomegalovirus Open Reading Frame TRL11/IRL11 Encodes an Immunoglobulin G Fc-Binding Protein
Authors: Lilley Brendan N. , Ploegh Hidde L. , Tirabassi Rebecca S. 
Published: July 2002

ABSTRACTSeveral herpesviruses encode Fc receptors that may play a role in preventing antibody-mediated clearance of the virus in vivo. Human cytomegalovirus (HCMV) induces an Fc-binding activity in cells upon infection, but the gene that encodes this Fc-binding protein has not been identified. Here, we demonstrate that the HCMV AD169 open reading frame TRL11 and its identical copy, IRL11, encode a type I membrane glycoprotein that possesses IgG Fc-binding capabilities.