bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role for 3-
O
-Sulfated Heparan Sulfate as the Receptor for Herpes Simplex Virus Type 1 Entry into Primary Human Corneal Fibroblasts
Authors: Tiwari Vaibhav , Clement Christian , Xu Ding , Valyi-Nagy Tibor , Yue Beatrice Y. J. T. , Liu Jian , Shukla Deepak 
Published: August 2006

ABSTRACT

Herpes simplex virus type 1 (HSV-1) infection of the corneal stroma remains a major cause of blindness. Primary cultures of corneal fibroblasts (CF) were tested and found susceptible to HSV-1 entry, which was confirmed by deconvolution imaging of infected cells. Plaque assay and real-time PCR demonstrated viral replication and hence a productive infection of CF by HSV-1. A role for glycoprotein D (gD) receptors in cultured CF was determined by gD interference assay. Reverse transcription-PCR analysis indicated expression of herpesvirus entry mediator and 3-
O
-sulfated (3-
O
S) heparan sulfate (HS)-generating enzyme 3-
O
sulfotransferase 3 (3-
O
ST-3) but not nectin-1 or nectin-2. Subsequently, HS isolated from these cells was found to contain two distinct disaccharides (IdoUA2S-AnMan3S and IdoUA2S-AnMan3S6S) that are representative of 3-
O
ST-3 activity. The following lines of evidence supported the important role of 3-
O
S HS as the mediator of HSV-1 entry into CF. (i) Blockage of entry was observed in CF treated with heparinases. The same enzymes had significantly less effect on HeLa cells that use nectin-1 as the entry receptor. (ii) Enzymatic removal of cell surface HS also removed the major gD-binding receptor, as evident from the reduced binding of gD to cells. (iii) Spinoculation assay demonstrated that entry blockage by heparinase treatment included the membrane fusion step. (iv) HSV-1 glycoprotein-induced cell-to-cell fusion was inhibited by either prior treatment of cells with heparinases or by HS preparations enriched in 3-
O
S HS. Taken together, the data in this report provide novel information on the role of 3-
O
S HS in mediating infection of CF, a natural target cell type.
Proteomic Analysis of the Kaposi's Sarcoma-Associated Herpesvirus Terminal Repeat Element Binding Proteins
Authors: Si Huaxin , Verma Subhash C. , Robertson Erle S. 
Published: August 2006

ABSTRACT
Terminal repeat (TR) elements of Kaposi's sarcoma-associated herpesvirus (KSHV), the potential origin sites of KSHV replication, have been demonstrated to play important roles in viral replication and transcription and are most likely also critical for the segregation of the KSHV genome to daughter cells. To search for the cellular proteins potentially involved in KSHV genome maintenance, we performed affinity chromatography analysis, using KSHV TR DNA as the affinity ligand. Proteomic analysis was then carried out to identify the TR-interacting proteins. We identified a total of 123 proteins from both KSHV-positive and -negative cells, among which most were identified exclusively from KSHV-positive cells. These proteins were categorized as proliferation/cell cycle regulatory proteins, proteins involved in spliceosome components, such as heterogeneous nuclear ribonuclear proteins, the DEAD/H family, the switch/sucrose nonfermenting protein family, splicing factors, RNA binding proteins, transcription regulation proteins, replication factors, modifying enzymes, and a number of proteins that could not be broadly categorized. To support the proteomic results, the presence of four candidate proteins, ATR, BRG1, NPM1 and PARP-1, in the elutions was further characterized in this study. The binding and colocalization of these proteins with the TR were verified using chromatin immunoprecipitation and immunofluorescence in situ hybridization analysis. These newly identified TR binding proteins provide a number of clues and potential links to understanding the mechanisms regulating the replication, transcription, and genome maintenance of KSHV. This study will facilitate the generation and testing of new hypotheses to further our understanding of the mechanisms involved in KSHV persistence and its associated pathogenesis.
AIDS Vaccination Studies with an Ex Vivo Feline Immunodeficiency Virus Model: Analysis of the Accessory ORF-A Protein and DNA as Protective Immunogens
Authors: Pistello Mauro , Bonci Francesca , Flynn J. Norman , Mazzetti Paola , Isola Patrizia , Zabogli Elisa , Camerini Valentina , Matteucci Donatella , Freer Giulia , Pelosi Paolo , Bendinelli Mauro 
Published: August 2006

ABSTRACT

Determining which antigen must be included in AIDS vaccines to confer maximum protection is of utmost importance. In primate models, vaccines consisting of or including accessory viral proteins have yielded conflicting results. We investigated the protective potential of the accessory protein ORF-A of feline immunodeficiency virus (FIV) in cats. All three immunization strategies used (protein alone in alum adjuvant, DNA alone, or DNA prime-protein boost) clearly generated detectable immune responses. Upon challenge with ex vivo homologous FIV, ORF-A-immunized cats showed distinct enhancement of acute-phase infection relative to mock-immunized animals given alum or empty vector DNA. This effect was tentatively attributed to increased expression of the FIV receptor CD134 that was observed in the immunized cats. However, at subsequent sampling points that were continued for up to 10 months postchallenge, the average plasma viral loads of the ORF-A-immunized animals were slightly but consistently reduced relative to those of the control animals. In addition, CD4
+
T lymphocytes in the circulation system declined more slowly in immunized animals than in control animals. These findings support the contention that immunization with lentiviral accessory proteins can improve the host's ability to control virus replication and slow down disease progression but also draw attention to the fact that even simple immunogens that eventually contribute to protective activity can transiently exacerbate subsequent lentiviral infections.
Hepatitis C Virus Core Protein Blocks Interferon Signaling by Interaction with the STAT1 SH2 Domain
Authors: Lin Wenyu , Kim Sun Suk , Yeung Elaine , Kamegaya Yoshitaka , Blackard Jason T. , Kim Kyung Ah , Holtzman Michael J. , Chung Raymond T. 
Published: August 2006

ABSTRACT
Emerging data have indicated that hepatitis C virus (HCV) subverts the host antiviral response to ensure its persistence. We previously demonstrated that HCV protein expression suppresses type I interferon (IFN) signaling by leading to the reduction of phosphorylated STAT1 (P-STAT1). We also demonstrated that HCV core protein directly bound to STAT1. However, the detailed mechanisms by which HCV core protein impacts IFN signaling components have not been fully clarified. In this report, we show that the STAT1 interaction domain resides in the N-terminal portion of HCV core (amino acids [aa] 1 to 23). This domain is also required to produce P-STAT1 reduction and inhibit IFN signaling transduction. Conversely, the C-terminal region of STAT1, specifically the SH2 domain (aa 577 to 684), is required for the interaction of HCV core with STAT1. The STAT1 SH2 domain is critical for STAT1 hetero- or homodimerization. We propose a model by which the binding of HCV core to STAT1 results in decreased P-STAT, blocked STAT1 heterodimerization to STAT2, and, therefore, reduced IFN-stimulated gene factor-3 binding to DNA and disrupted IFN-stimulated gene transcription.
Kaposi's Sarcoma-Associated Herpesvirus Latency-Associated Nuclear Antigen Interacts with Bromodomain Protein Brd4 on Host Mitotic Chromosomes
Authors: You Jianxin , Srinivasan Viswanathan , Denis Gerald V. , Harrington William J. , Ballestas Mary E. , Kaye Kenneth M. , Howley Peter M. 
Published: August 2006

ABSTRACT

The latency-associated nuclear antigen (LANA) of Kaposi's sarcoma-associated herpesvirus (KSHV) is required for viral episome maintenance in host cells during latent infection. Two regions of the protein have been implicated in tethering LANA/viral episomes to the host mitotic chromosomes, and LANA chromosome-binding sites are subjects of high interest. Because previous studies had identified bromodomain protein Brd4 as the mitotic chromosome anchor for the bovine papillomavirus E2 protein, which tethers the viral episomes to host mitotic chromosomes (J. You, J. L. Croyle, A. Nishimura, K. Ozato, and P. M. Howley, Cell
117:
349-360, 2004, and J. You, M. R. Schweiger, and P. M. Howley, J. Virol.
79:
14956-14961, 2005), we examined whether KSHV LANA interacts with Brd4. We found that LANA binds Brd4 in vivo and in vitro and that the binding is mediated by a direct protein-protein interaction between the ET (extraterminal) domain of Brd4 and a carboxyl-terminal region of LANA previously implicated in chromosome binding. Brd4 associates with mitotic chromosomes throughout mitosis and demonstrates a strong colocalization with LANA and the KSHV episomes on host mitotic chromosomes. Although another bromodomain protein, RING3/Brd2, binds to LANA in a similar fashion in vitro, it is largely excluded from the mitotic chromosomes in KSHV-uninfected cells and is partially recruited to the chromosomes in KSHV-infected cells. These data identify Brd4 as an interacting protein for the carboxyl terminus of LANA on mitotic chromosomes and suggest distinct functional roles for the two bromodomain proteins RING3/Brd2 and Brd4 in LANA binding. Additionally, because Brd4 has recently been shown to have a role in transcription, we examined whether Brd4 can regulate the CDK2 promoter, which can be transactivated by LANA.
Genome Characterization of Lipid-Containing Marine Bacteriophage PM2 by Transposon Insertion Mutagenesis
Authors: Krupovič Mart , Vilen Heikki , Bamford Jaana K. H. , Kivelä Hanna M. , Aalto Juha-Matti , Savilahti Harri , Bamford Dennis H. 
Published: August 2006

ABSTRACT

Bacteriophage PM2 presently is the only member of the
Corticoviridae
family. The virion consists of a protein-rich lipid vesicle, which is surrounded by an icosahedral protein capsid. The lipid vesicle encloses a supercoiled circular double-stranded DNA genome of 10,079 bp. PM2 belongs to the marine phage community and is known to infect two gram-negative
Pseudoalteromonas
species. In this study, we present a characterization of the PM2 genome made using the in vitro transposon insertion mutagenesis approach. Analysis of 101 insertion mutants yielded information on the essential and dispensable regions of the PM2 genome and led to the identification of several new genes. A number of lysis-deficient mutants as well as mutants displaying delayed- and/or incomplete-lysis phenotypes were identified. This enabled us to identify novel lysis-associated genes with no resemblance to those previously described from other bacteriophage systems. Nonessential genome regions are discussed in the context of PM2 genome evolution.
An Element of the Tertiary Structure of Peach Latent Mosaic Viroid RNA Revealed by UV Irradiation
Authors: Hernández Carmen , Di Serio Francesco , Ambrós Silvia , Daròs José-Antonio , Flores Ricardo 
Published: August 2006

ABSTRACT

Following UV irradiation, denaturing polyacrylamide gel electrophoresis and Northern blot hybridization revealed a cross-link in
Peach latent mosaic viroid
(PLMVd) plus-strand RNA. Primer extension and partial alkaline hydrolysis of the UV-irradiated PLMVd plus-strand RNA resulting from the hammerhead-mediated self-cleavage mapped the cross-link at U81 and at the 3′-terminal C289 (or at a very proximal nucleotide). Supporting this notion, in vitro-synthesized PLMVd plus-strand RNAs with short insertions/deletions at their 3′ termini failed to cross-link. Because U81 and C289 are conserved in PLMVd variants and because the initiation site of PLMVd minus-strand RNA maps at a short double-stranded motif containing C289, the UV-photo-cross-linkable element of tertiary structure may be functionally significant. A second cross-linked species similar in size and sequence to the monomeric circular PLMVd form, observed in some PLMVd variants, probably derives from UV-induced ligation of the two termini resulting from self-cleavage.
Human Cytomegalovirus Inhibits Neuronal Differentiation and Induces Apoptosis in Human Neural Precursor Cells
Authors: Odeberg Jenny , Wolmer Nina , Falci Scott , Westgren Magnus , Seiger Åke , Söderberg-Nauclér Cecilia 
Published: August 2006

ABSTRACT
Human cytomegalovirus (HCMV) is the most common cause of congenital infections in developed countries, with an incidence varying between 0.5 and 2.2% and consequences varying from asymptomatic infection to lethal conditions for the fetus. Infants that are asymptomatic at birth may still develop neurological sequelae, such as hearing loss and mental retardation, at a later age. Infection of neural stem and precursor cells by HCMV and consequent disruption of the proliferation, differentiation, and/or migration of these cells may be the primary mechanism underlying the development of brain abnormalities. In the present investigation, we demonstrate that human neural precursor cells (NPCs) are permissive for HCMV infection, by both the laboratory strain Towne and the clinical isolate TB40, resulting in 55% and 72% inhibition of induced differentiation of human NPCs into neurons, respectively, when infection occurred at the onset of differentiation. This repression of neuronal differentiation required active viral replication and involved the expression of late HCMV gene products. This capacity of HCMV to prevent neuronal differentiation declined within 24 h after initiation of differentiation. Furthermore, the rate of cell proliferation in infected cultures was attenuated. Surprisingly, HCMV-infected cells exhibited an elevated frequency of apoptosis at 7 days following the onset of differentiation, at which time approximately 50% of the cells were apoptotic at a multiplicity of infection of 10. These findings indicate that HCMV has the capacity to reduce the ability of human NPCs to differentiate into neurons, which may offer one explanation for the abnormalities in brain development associated with congenital HCMV infection.
Identification of Amino Acid Residues within Simian Virus 40 Capsid Proteins Vp1, Vp2, and Vp3 That Are Required for Their Interaction and for Viral Infection
Authors: Nakanishi Akira , Nakamura Akiko , Liddington Robert , Kasamatsu Harumi 
Published: August 2006

ABSTRACT
Interaction of simian virus 40 (SV40) major capsid protein Vp1 with the minor capsid proteins Vp2 and Vp3 is an integral aspect of the SV40 architecture. Two Vp3 sequence elements mediate Vp1 pentamer binding in vitro, Vp3 residues 155 to 190, or D1, and Vp3 residues 222 to 234, or D2. Of the two, D1 but not D2 was necessary and sufficient to direct the interaction with Vp1 in vivo. Rational mutagenesis of Vp3 residues (Phe157, Ile158, Pro164, Gly165, Gly166, Leu177, and Leu181) or Vp1 residues (Val243 and Leu245), based on a structural model of the SV40 Vp1 pentamer complexed with Vp3 D1, was carried out to disrupt the interaction between Vp1 and Vp3 and to study the consequences of these mutations for viral viability. Altering these residues to bulky, charged residues blocked the interaction in vitro. When these alterations were introduced into the viral genome, they reduced viral viability. Mutants with alterations in Vp1 Val243, Leu245, or both to glutamate were nearly nonviable, whereas those with Vp3 alterations reduced, but did not eliminate, viability. Our results defined the residues of Vp1 and the minor capsid proteins that are essential for both the interaction of the capsid proteins and viral viability in permissive cells.
Altered Central Nervous System Gene Expression Caused by Congenitally Acquired Persistent Infection with Lymphocytic Choriomeningitis Virus
Authors: Kunz Stefan , Rojek Jillian M. , Roberts Amanda J. , McGavern Dorian B. , Oldstone Michael B. A. , de la Torre Juan Carlos 
Published: August 2006

ABSTRACTNeonatal infection of most mouse strains with lymphocytic choriomeningitis virus (LCMV) leads to a life-long persistent infection characterized by high virus loads in the central nervous system (CNS) in the absence of inflammation and tissue destruction. These mice, however, exhibit impaired learning and memory. The occurrence of cognitive defects in the absence of overt CNS pathology led us to the hypothesis that chronic virus infection may contribute to neuronal dysfunction by altering the host's gene expression profile. To test this hypothesis, we examined the impact of LCMV persistence on host gene expression in the CNS. To model the natural route of human congenital CNS infection observed with a variety of viruses, we established a persistently infected mouse colony where the virus was maintained via vertical transmission from infected mothers to offspring (LCMV-cgPi). LCMV-cgPi mice exhibited a lifelong persistent infection involving the CNS; the infection was associated with impaired spatial-temporal learning. Despite high viral loads in neurons of the brains of adult LCMV-cgPi mice, we detected changes in the host's CNS gene expression for only 75 genes, 56 and 19 being significantly induced and reduced, respectively. The majority of the genes induced in the brain of LCMV-cgPi mice were interferon (IFN)-stimulated genes (ISGs) and included the transcription factors STAT1 and IRF9, the ISG15 protease UBP43, and the glucocorticoid attenuated-response genes GARG16 and GARG49. Based on their crucial role in antiviral defense, these ISGs may play an important role in limiting viral spread and replication. However, since IFNs have also been implicated in adverse effects on neuronal function, the chronic induction of some ISGs may also contribute to the observed cognitive impairment.
Adeno-Associated Virus Type 2 Contains an Integrin α5β1 Binding Domain Essential for Viral Cell Entry
Authors: Asokan Aravind , Hamra Julie B. , Govindasamy Lakshmanan , Agbandje-McKenna Mavis , Samulski Richard J. 
Published: August 2006

ABSTRACT
Integrins have been implicated as coreceptors in the infectious pathways of several nonenveloped viruses. For example, adenoviruses are known to interact with αV integrins by virtue of a high-affinity arginine-glycine-aspartate (RGD) domain present in the penton bases of the capsids. In the case of adeno-associated virus type 2 (AAV2), which lacks this RGD motif, integrin αVβ5 has been identified as a coreceptor for cellular entry. However, the molecular determinants of AAV2 capsid-integrin interactions and the potential exploitation of alternative integrins as coreceptors by AAV2 have not been established thus far. In this report, we demonstrate that integrin α5β1 serves as an alternative coreceptor for AAV2 infection in human embryonic kidney 293 cells. Such interactions appear to be mediated by a highly conserved domain that contains an asparagine-glycine-arginine (NGR) motif known to bind α5β1 integrin with moderate affinity. The mutation of this domain reduces transduction efficiency by an order of magnitude relative to that of wild-type AAV2 vectors in vitro and in vivo. Further characterization of mutant and wild-type AAV2 capsids through transduction assays in cell lines lacking specific integrins, cell adhesion studies, and cell surface/solid-phase binding assays confirmed the role of the NGR domain in promoting AAV2-integrin interactions. Molecular modeling studies suggest that NGR residues form a surface loop close to the threefold axis of symmetry adjacent to residues previously implicated in binding heparan sulfate, the primary receptor for AAV2. The aforementioned results suggest that the internalization of AAV2 in 293 cells might follow a “click-to-fit” mechanism that involves the cooperative binding of heparan sulfate and α5β1 integrin by the AAV2 capsids.
Transcriptional Profiling Reveals a Possible Role for the Timing of the Inflammatory Response in Determining Susceptibility to a Viral Infection
Authors: Ruby Thomas , Whittaker Catherine , Withers David R. , Chelbi-Alix Mounira K. , Morin Veronique , Oudin Anne , Young John R. , Zoorob Rima 
Published: August 2006

ABSTRACTUsing a novel cDNA microarray prepared from sources of actively responding immune system cells, we have investigated the changes in gene expression in the target tissue during the early stages of infection of neonatal chickens with infectious bursal disease virus. Infections of two lines of chickens previously documented as genetically resistant and sensitive to infection were compared in order to ascertain early differences in the response to infection that might provide clues to the mechanism of differential genetic resistance. In addition to major changes that could be explained by previously described changes in infected tissue, some differences in gene expression on infection, and differences between the two chicken lines, were observed that led to a model for resistance in which a more rapid inflammatory response and more-extensive p53-related induction of apoptosis in the target B cells might limit viral replication and consequent pathology. Ironically, the effect in the asymptomatic neonatal infection is that more-severe B-cell depletion is seen in the more genetically resistant chicken. Changes of expression of many chicken genes of unknown function, indicating possible roles in the response to infection, may aid in the functional annotation of these genes.
Characterization of a Potent Refractory State and Persistence of Herpes Simplex Virus 1 in Cell Culture
Authors: Barreca Cristina , O'Hare Peter 
Published: August 2006

ABSTRACT
Herpes simplex virus (HSV) normally undergoes productive cytocidal infection in culture and is thought of as relatively resistant to innate immune responses such as interferon. We previously described an unusual pattern of infection in culture in MDBK cells, which after initial productive infection, surprisingly resulted in progressive suppression of replication and cell recovery. The dominance of the refractory state was due to the inability to suppress interferon production and subsequent paracrine signaling. Here, using a wild-type HSV-1 strain expressing green fluorescent protein (GFP)-VP16, we analyze aspects of long-term HSV persistence resulting from this oscillating refractory state. We show that the gradual suppression of GFP-VP16 expression correlated with a biphasic pattern of accumulation of viral DNA and extracellular virus titers. We quantify virus maintenance in a minor subpopulation of cells during subculture, show the reemergence of virus by infectious center assay, and demonstrate that this required intracellular events over a 24- to 48-h time course. We also demonstrate that conditioned medium (cMed) from infected cells induced a profound shutoff of HSV gene expression at the transcriptional level. Finally, we demonstrate that this suppression was extremely rapid, requiring only 1 h of treatment to essentially abolish HSV immediate-early expression, and surprisingly persisted for almost 2 days after removal of the cMed. These combined effects underpin the oscillating effect both in plaque progression, where infection spreads but is overwhelmed by the accumulation of inhibitory components, enabling cell recovery, and virus maintenance in a subpopulation of cells. These results may be relevant to consider in studies of HSV latency in different animal models.