bluuebunny/crossref_metadata_2025_split huggingface dataset:
In Vivo Genomic Footprinting of the Human T-Cell Leukemia Virus Type 1 (HTLV-1) Long Terminal Repeat Enhancer Sequences in HTLV-1-Infected Human T-Cell Lines with Different Levels of Tax I Activity
Authors: Datta Shoibal , Kothari Nayantara H. , Fan Hung 
Published: July 2002

ABSTRACT
The Tax protein of human T-cell leukemia virus type 1 (HTLV-1) enhances viral gene expression through sequences in the U3 region of the viral long terminal repeat. These sequences consist of three imperfect 21-bp repeats (TRE-1s) and a region between the promoter-central and promoter-proximal 21-bp repeats (TRE-2). The TRE-1s contain a core cyclic AMP response element (CRE) motif and can be bound by CREB, ATF-1, ATF-2, and other members of the CREB-ATF superfamily of transcription factors. Tax enhances CREB binding to TRE-1 in vitro, and it promotes dimerization of CREB as well as other bZIP proteins. Using ligation-mediated PCR on in vivo dimethyl sulfate-treated HTLV-1-infected cell lines MT-2 and MT-4, we have compiled a profile of protein occupancy in the HTLV-1 enhancer sequences in the presence of high (MT-2) and low (MT-4) levels of biologically active Tax I. The in vivo footprinting showed that all three TRE-1s were bound by protein(s), but only in MT-2 cells. In MT-2 cells, all TRE-1s showed strong protection of the G residues in the central CRE, and the footprints extended to differing degrees into the GC-rich flanking sequences. This indicated Tax I-dependent loading of transcription factors onto the HTLV-1 TRE-1s in vivo. In vivo footprinting on TRE-2 indicated that this region was bound by proteins regardless of the Tax I status of the cell line. However, the presence of Tax I increased the extent and altered the profile of proteins binding TRE-2 in vivo.
Sindbis-Group Alphavirus Replication in Periosteum and Endosteum of Long Bones in Adult Mice
Authors: Heise Mark T. , Simpson Dennis A. , Johnston Robert E. 
Published: July 2002

ABSTRACTSeveral alphaviruses, including the Sindbis-group viruses, Ross River virus, O'nyong-nyong virus, and Chikungunya virus, are associated with outbreaks of acute and persistent arthralgia and arthritis in humans. Mechanisms underlying alphavirus-induced arthralgia and arthritis are not clearly understood, though direct viral replication within or around the affected joints is thought to contribute to disease. S.A.AR86 is a Sindbis-group alphavirus closely related to the arthralgia-associated Ockelbo and GirdwoodS.A viruses. Following inoculation with S.A.AR86 derived from a molecular clone, infectious virus was isolated from bone and joint tissue 1 to 6 days postinfection. Studies using either in situ hybridization or S.A.AR86-derived double promoter viruses and replicons expressing green fluorescent protein localized sites of viral replication to the periosteum, tendons, and endosteum within the epiphyses of the long bones adjacent to articular joints. These results demonstrate that alphaviruses associated with arthralgia in humans replicate within bone-associated connective tissue adjacent to articular joints in an adult mouse model.
Cytoplasmic Domain Signal Sequences That Mediate Transport of Varicella-Zoster Virus gB from the Endoplasmic Reticulum to the Golgi
Authors: Heineman Thomas C. , Krudwig Nancy , Hall Susan L. 
Published: July 2002

ABSTRACT
Normal herpesvirus assembly and egress depend on the correct intracellular localization of viral glycoproteins. While several post-Golgi transport motifs have been characterized within the cytoplasmic domains of various viral glycoproteins, few specific endoplasmic reticulum (ER)-to-Golgi transport signals have been described. We report the identification of two regions within the 125-amino-acid cytoplasmic domain of Varicella-Zoster virus gB that are required for its ER-to-Golgi transport. Native gB or gB containing deletions and specific point mutations in its cytoplasmic domain was expressed in mammalian cells. ER-to-Golgi transport of gB was assessed by indirect immunofluorescence and by the acquisition of Golgi-dependent posttranslational modifications. These studies revealed that the ER-to-Golgi transport of gB requires a nine-amino-acid region (YMTLVSAAE) within its cytoplasmic domain. Mutations of individual amino acids within this region markedly impaired the transport of gB from the ER to the Golgi, indicating that this domain functions by a sequence-dependent mechanism. Deletion of the C-terminal 17 amino acids of the gB cytoplasmic domain was also shown to impair the transport of gB from the ER to the Golgi. However, internal mutations within this region did not disrupt the transport of gB, indicating that its function during gB transport is not sequence dependent. Native gB is also transported to the nuclear membrane of transfected cells. gB lacking as many as 67 amino acids from the C terminus of its cytoplasmic domain continued to be transported to the nuclear membrane at apparently normal levels, indicating that the cytoplasmic domain of gB is not required for nuclear membrane localization.
Canine Adenovirus Type 2 Attachment and Internalization: Coxsackievirus-Adenovirus Receptor, Alternative Receptors, and an RGD-Independent Pathway
Authors: Soudais Claire , Boutin Sylvie , Hong Saw See , Chillon Miguel , Danos Olivier , Bergelson Jeffrey M. , Boulanger Pierre , Kremer Eric J. 
Published: July 2002

ABSTRACTThe best-characterized receptors for adenoviruses (Ads) are the coxsackievirus-Ad receptor (CAR) and integrins αvβ5and αvβ3, which facilitate entry. The αvintegrins recognize an Arg-Gly-Asp (RGD) motif found in some extracellular matrix proteins and in the penton base in most human Ads. Using a canine adenovirus type 2 (CAV-2) vector, we found that CHO cells that express CAR but not wild-type CHO cells are susceptible to CAV-2 transduction. Cells expressing αMβ2integrins or major histocompatibility complex class I (MHC-I) molecules but which do not express CAR were not transduced. Binding assays showed that CAV-2 attaches to a recombinant soluble form of CAR and that Ad type 5 (Ad5) fiber, penton base, and an anti-CAR antibody partially blocked attachment. Using fluorescently labeled CAV-2 particles, we found that in some cells nonpermissive for transduction, inhibition was at the point of internalization and not attachment. The transduction efficiency of CAV-2, which lacks an RGD motif, surprisingly mimicked that of Ad5 when tested in cells selectively expressing αvβ5and αvβ3integrins. Our results demonstrate that CAV-2 transduction is augmented by CAR and possibly by αvβ5, though transduction can be CAR and αvβ3/5independent but is αMβ2, MHC-I, and RGD independent, demonstrating a transduction mechanism which is distinct from that of Ad2/5.
Life Cycle of an Endogenous Retrovirus,
ZAM
, in
Drosophila melanogaster
Authors: Leblanc P. , Desset S. , Giorgi F. , Taddei A. R. , Fausto A. M. , Mazzini M. , Dastugue B. , Vaury C. 
Published: July 2002

ABSTRACT

ZAM
is an
env
-containing member of the
gypsy
family of retrotransposons that represents a possible retrovirus of invertebrates. In this paper, we traced
ZAM
mobilization to get information about a potential path a retroelement may take to reach the germ line of its host. In situ hybridization on whole-mount tissues and immunocytochemistry analyses with antibodies raised against
ZAM
Gag and Env proteins have shown that all components necessary to assemble
ZAM
viral particles, i.e.,
ZAM
full-length RNAs and Gag and Env polypeptides, are coexpressed in a small set of follicle cells surrounding the oocyte. By electron microscopy, we have shown that
ZAM
viral particles are indeed detected in this somatic lineage of cells, which they leave and enter the closely apposed oocyte. Our data provide evidence that the vesicular traffic and yolk granules in the process of vitellogenesis play an important role in
ZAM
transfer to the oocyte. Our data support the possibility that vitellogenin transfer to the oocyte may help a retroelement pass to the germ line with no need of its envelope product.
Characterization of Transcripts Expressed from Human Herpesvirus 6A Strain GS Immediate-Early Region B U16-U17 Open Reading Frames
Authors: Flebbe-Rehwaldt Linda M. , Wood Charles , Chandran Bala 
Published: July 2002

ABSTRACT

Several gene fragments of human herpesvirus 6 (HHV-6) have been shown to activate the human immunodeficiency virus (HIV) type 1 long terminal repeat (LTR). An open reading frame (ORF) designated B701 (Y. Geng, B. Chandran, S. F. Josephs, and C. Wood, J. Virol. 66:1564–1570, 1992), found within a 22-kb HHV-6A strain GS [HHV-6A(GS)] genomic fragment and a 3.8-kb
Sal
I subfragment, was shown to activate the HIV LTR. B701, also known as HHV-6 U16, is located in the immediate-early B (IE-B) region of the genome. The sequence of the 3.8-kb genomic fragment of HHV-6A(GS) is nearly identical to the published sequence of HHV-6A strain U1102, with minor differences. The HHV-6A(GS) B701 ORF (U16) was used to screen an HHV-6A(GS) cDNA library, and two different but overlapping cDNAs were identified. These cDNAs represent differently spliced transcripts ending at different polyadenylation signals. The ORFs included in the cDNAs are positionally homologous to the human cytomegalovirus (HCMV) UL36 ORF. The ORF in one cDNA was generated by splicing together in frame ORFs U17 and U16, and the second cDNA included ORFs U16 and U15. A third differentially spliced cDNA (U16+), was identified by 5′ rapid amplification of cDNA ends. The predicted protein was identical to the U16 portion of the U17/U16 spliced gene product but did not include the U17 portion. 5′-extension analyses of the mRNAs demonstrated that at least two potential transcription initiation sites were used to express the transcripts encoding U17 and U16 gene products. Single-stranded U16 and U17 gene-specific RNA probes hybridized with at least five RNA species from infected cells and demonstrated that the expression of these transcripts was differentially regulated. The U17/U16 spliced gene products were expressed at IE times after infection, but a multiply spliced gene product encoded by U16 was expressed as a late gene. The U17/U16 and the U16+ gene products transactivated the HIV LTR. Thus, while there are similarities to the HCMV UL36-UL38 gene family, some of the IE-B U17/U16 transcripts are unique to HHV-6.
Mutational Analysis of Conserved Domains within the Cytoplasmic Tail of gp41 from Human Immunodeficiency Virus Type 1: Effects on Glycoprotein Incorporation and Infectivity
Authors: Piller Sabine C. , Dubay John W. , Derdeyn Cynthia A. , Hunter Eric 
Published: July 2002

ABSTRACT
The transmembrane (TM) glycoprotein gp41 of human immunodeficiency virus type 1 possesses an unusually long (∼150 amino acids) and highly conserved cytoplasmic region. Previous studies in which this cytoplasmic tail had been deleted partially or entirely have suggested that it is important for virus infectivity and incorporation of the gp120-gp41 glycoprotein complex into virions. To determine which regions of the conserved C-terminal domains are important for glycoprotein incorporation and infectivity, several small deletions and amino acid substitutions which modify highly conserved motifs were constructed in the infectious proviral background of NL4.3. The effects of these mutations on infectivity and glycoprotein incorporation into virions produced from transfected 293-T cells and infected H9 and CEM×174 cells were determined. With the exception of a mutation deleting amino acids QGL, all of the constructs resulted in decreased infectivity of the progeny virus both in a single-round infectivity assay and in a multiple-infection assay in H9 and CEM×174 cells. For most mutations, the decreased infectivity was correlated with a decreased incorporation of glycoprotein into virions. Substitution of the arginines (residues 839 and 846) with glutamates also reduced infectivity, but without a noticeable decrease in the amount of glycoprotein incorporated into virus produced from infected T cells. These results demonstrate that minor alterations in the conserved C-terminal region of the gp41 cytoplasmic tail can result in reductions in infectivity that correlate for most but not all constructs with a decrease in glycoprotein incorporation. Observed cell-dependent differences suggest the involvement of cellular factors in regulating glycoprotein incorporation and infectivity.
Abundant Defective Viral Particles Budding from Microglia in the Course of Retroviral Spongiform Encephalopathy
Authors: Hansen Regine , Czub Stefanie , Werder Evi , Herold Jens , Gosztonyi Georg , Gelderblom Hans , Schimmer Simone , Mazgareanu Stefan , ter Meulen Volker , Czub Markus 
Published: July 2002

ABSTRACT
A pathogenetic hallmark of retroviral neurodegeneration is the affinity of neurovirulent retroviruses for microglia cells, while degenerating neurons are excluded from retroviral infections. Microglia isolated ex vivo from rats peripherally infected with a neurovirulent retrovirus released abundant mature type C virions; however, infectivity associated with microglia was very low. In microglia, viral transcription was unaffected but envelope proteins were insufficiently cleaved into mature viral proteins and were not detected on the microglia cell surface. These microglia-specific defects in envelope protein translocation and processing not only may have prevented formation of infectious virus particles but also may have caused further cellular defects in microglia with the consequence of indirect neuronal damage. It is conceivable that similar events play a role in neuro-AIDS.
An Envelope Glycoprotein of the Human Endogenous Retrovirus HERV-W Is Expressed in the Human Placenta and Fuses Cells Expressing the Type D Mammalian Retrovirus Receptor
Authors: Blond Jean-Luc , Lavillette Dimitri , Cheynet Valérie , Bouton Olivier , Oriol Guy , Chapel-Fernandes Sylvie , Mandrand Bernard , Mallet François , Cosset François-Loïc 
Published: July 2002

ABSTRACT

A new human endogenous retrovirus (HERV) family, termed HERV-W, was recently described (J.-L. Blond, F. Besème, L. Duret, O. Bouton, F. Bedin, H. Perron, B. Mandrand, and F. Mallet, J. Virol. 73:1175–1185, 1999). HERV-W mRNAs were found to be specifically expressed in placenta cells, and an
env
cDNA containing a complete open reading frame was recovered. In cell-cell fusion assays, we demonstrate here that the product of the HERV-W
env
gene is a highly fusogenic membrane glycoprotein. Transfection of an HERV-W Env expression vector in a panel of cell lines derived from different species resulted in formation of syncytia in primate and pig cells upon interaction with the type D mammalian retrovirus receptor. Moreover, envelope glycoproteins encoded by HERV-W were specifically detected in placenta cells, suggesting that they may play a physiological role during pregnancy and placenta formation.
Rta of Murine Gammaherpesvirus 68 Reactivates the Complete Lytic Cycle from Latency
Authors: Wu Ting-Ting , Usherwood Edward J. , Stewart James P. , Nash Anthony A. , Sun Ren 
Published: July 2002

ABSTRACT

Herpesviruses are characterized as having two distinct life cycle phases: lytic replication and latency. The mechanisms of latency establishment and maintenance, as well as the switch from latency to lytic replication, are poorly understood. Human gammaherpesviruses, including Epstein-Barr virus (EBV) and human herpesvirus-8 (HHV-8), also known as Kaposi's sarcoma-associated herpesvirus (KSHV), are associated with lymphoproliferative diseases and several human tumors. Unfortunately, the lack of cell lines to support efficient de novo productive infection and restricted host ranges of EBV and HHV-8 make it difficult to explore certain important biological questions. Murine gammaherpesvirus 68 (MHV-68, or γHV68) can establish de novo lytic infection in a variety of cell lines and is also able to infect laboratory mice, offering an ideal model with which to study various aspects of gammaherpesvirus infection. Here we describe in vitro studies of the mechanisms of the switch from latency to lytic replication of MHV-68. An MHV-68 gene,
rta
(replication and transcription activator), encoded primarily by open reading frame 50 (ORF50), is homologous to the
rta
genes of other gammaherpesviruses, including HHV-8 and EBV. HHV-8 and EBV Rta have been shown to play central roles in viral reactivation from latency. We first studied the kinetics of MHV-68
rta
gene transcription during de novo lytic infection. MHV-68
rta
was predominantly expressed as a 2-kb immediate-early transcript. Sequence analysis of MHV-68
rta
cDNA revealed that an 866-nucleotide intron 5′ of ORF50 was removed to create the Rta ORF of 583 amino acids. To test the functions of MHV-68 Rta in reactivation, a plasmid expressing Rta was transfected into a latently infected cell line, S11E, which was established from a B-cell lymphoma in an MHV-68-infected mouse. Rta induced expression of viral early and late genes, lytic replication of viral DNA, and production of infectious viral particles. We conclude that Rta alone is able to disrupt latency, activate viral lytic replication, and drive the lytic cycle to completion. This study indicates that MHV-68 provides a valuable model for investigating regulation of the balance between latency and lytic replication in vitro and in vivo.
Recombinant Bovine/Human Parainfluenza Virus Type 3 (B/HPIV3) Expressing the Respiratory Syncytial Virus (RSV) G and F Proteins Can Be Used To Achieve Simultaneous Mucosal Immunization against RSV and HPIV3
Authors: Schmidt Alexander C. , McAuliffe Josephine M. , Murphy Brian R. , Collins Peter L. 
Published: July 2002

ABSTRACT
Recombinant bovine/human parainfluenza virus type 3 (rB/HPIV3), a recombinant bovine PIV3 (rBPIV3) in which the F and HN genes were replaced with their HPIV3 counterparts, was used to express the major protective antigens of respiratory syncytial virus (RSV) in order to create a bivalent mucosal vaccine against RSV and HPIV3. The attenuation of rB/HPIV3 is provided by the host range restriction of the BPIV3 backbone in primates. RSV G and F open reading frames (ORFs) were placed under the control of PIV3 transcription signals and inserted individually into the rB/HPIV3 genome in the promoter-proximal position preceding the nucleocapsid protein gene. The recombinant PIV3 expressing the RSV G ORF (rB/HPIV3-G1) was not restricted in its replication in vitro, whereas the virus expressing the RSV F ORF (rB/HPIV3-F1) was eightfold restricted compared to its rB/HPIV3 parent. Both viruses replicated efficiently in the respiratory tract of hamsters, and each induced RSV serum antibody titers similar to those induced by RSV infection and anti-HPIV3 titers similar to those induced by HPIV3 infection. Immunization of hamsters with rB/HPIV3-G1, rB/HPIV3-F1, or a combination of both viruses resulted in a high level of resistance to challenge with RSV or HPIV3 28 days later. These results describe a vaccine strategy that obviates the technical challenges associated with a live attenuated RSV vaccine, providing, against the two leading viral agents of pediatric respiratory tract disease, a bivalent vaccine whose attenuation phenotype is based on the extensive host range sequence differences of BPIV3.
“Stealth” Adenoviruses Blunt Cell-Mediated and Humoral Immune Responses against the Virus and Allow for Significant Gene Expression upon Readministration in the Lung
Authors: Croyle Maria A. , Chirmule Narendra , Zhang Yi , Wilson James M. 
Published: July 2002

ABSTRACTMost of the early gene therapy trials for cystic fibrosis have been with adenovirus vectors. First-generation viruses with E1a and E1b deleted are limited by transient expression of the transgene and substantial inflammatory responses. Gene transfer is also significantly curtailed following a second dose of virus. In an effort to reduce adenovirus-associated inflammation, capsids of first-generation vectors were modified with various activated monomethoxypolyethylene glycols. Cytotoxic T-lymphocyte production was significantly reduced in C57BL/6 mice after a single intratracheal administration of modified vectors, and length of gene expression was extended from 4 to 42 days. T-cell subsets from mice exposed to the conjugated vectors demonstrated a marked decrease in Th1 responses and slight enhancement of Th2 responses compared to animals dosed with native virus. Neutralizing antibodies (NAB) against adenovirus capsid proteins were reduced in serum and bronchoalveolar lavage fluid of animals after a single dose of modified virus, allowing significant levels of gene expression upon rechallenge with native adenovirus. Modification with polyethylene glycol (PEG) also allowed substantial gene expression from the new vectors in animals previously immunized with unmodified virus. However, gene expression was significantly reduced after two doses of the same PEG-conjugated vector. Alternating the activation group of PEG between doses did produce significant gene expression upon readministration. This technology in combination with second-generation or helper-dependent adenovirus could produce dosing strategies which promote successful readministration of vector in clinical trials and marked expression in patients with significant anti-adenovirus NAB levels and reduce the possibility of immune reactions against viral vectors for gene therapy.
A Herpes Simplex Virus Type 1 γ34.5 Second-Site Suppressor Mutant That Exhibits Enhanced Growth in Cultured Glioblastoma Cells Is Severely Attenuated in Animals
Authors: Mohr Ian , Sternberg David , Ward Stephen , Leib David , Mulvey Matthew , Gluzman Yakov 
Published: July 2002

ABSTRACT
We describe here the neurovirulence properties of a herpes simplex virus type 1 γ34.5 second-site suppressor mutant. γ34.5 mutants are nonneurovirulent in animals and fail to grow in a variety of cultured cells due to a block at the level of protein synthesis. Extragenic suppressors with restored capacity to replicate in cells that normally do not support the growth of the parental γ34.5 deletion mutant have been isolated. Although the suppressor virus reacquires the ability to grow in nonpermissive cultured cells, it remains severely attenuated in mice and is indistinguishable from the mutant γ34.5 parent virus at the doses investigated. Repairing the γ34.5 mutation in the suppressor mutant restores neurovirulence to wild-type levels. These studies illustrate that (i) the protein synthesis and neurovirulence defects observed in γ34.5 mutant viruses can be genetically separated by an extragenic mutation at another site in the viral chromosome; (ii) the extragenic suppressor mutation does not affect neurovirulence; and (iii) the attenuated γ34.5 mutant, which replicates poorly in many cell types, can be modified by genetic selection to generate a nonpathogenic variant that regains the ability to grow robustly in a nonpermissive glioblastoma cell line. As this γ34.5 second-site suppressor variant is attenuated and replicates vigorously in neoplastic cells, it may have potential as a replication-competent, viral antitumor agent.