bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activation of the
grp78
and
grp94
Promoters by Hepatitis C Virus E2 Envelope Protein
Authors: Liberman Eva , Fong Yiu-Lian , Selby Mark J. , Choo Qui-Lim , Cousens Lawrence , Houghton Michael , Benedict Yen T. S. 
Published: December 2019

ABSTRACT
The hepatitis C virus E1 and E2 envelope proteins are targeted to the endoplasmic reticulum, but instead of being secreted, they are retained in a pre-Golgi compartment, at least partly in a misfolded state. Since secretory proteins which are retained in the endoplasmic reticulum frequently can activate the transcription of intraluminal chaperone proteins, we measured the effect of the E1 and E2 proteins on the promoters of two such chaperones, GRP78 (BiP) and GRP94. We found that E2 but not E1 protein activates these two promoters, as assayed by a reporter gene system. Furthermore, E2 but not E1 protein induces the synthesis of GRP78 from the endogenous cellular gene. We also found that E2 but not E1 protein expressed in mammalian cells is bound tightly to GRP78. This association may explain the ability of E2 protein to activate transcription, since GRP78 has been postulated to be a sensor of stress in the endoplasmic reticulum. Since overexpression of GRP78 has been shown to decrease the sensitivity of cells to killing by cytotoxic T lymphocytes and to increase tumorigenicity and resistance to antitumor drugs, this activity of E2 protein may be involved in the pathogenesis of hepatitis C virus-induced diseases.
Intrastrain Variants of Herpes Simplex Virus Type 1 Isolated from a Neonate with Fatal Disseminated Infection Differ in the ICP34.5 Gene, Glycoprotein Processing, and Neuroinvasiveness
Authors: Bower John R. , Mao Hanwen , Durishin Catherine , Rozenbom Edgardo , Detwiler Michelle , Rempinski Donald , Karban Tracy L. , Rosenthal Ken S. 
Published: December 2019

ABSTRACTTwo intrastrain variants of herpes simplex virus type 1 (HSV-1) were isolated from a newborn with fatal disseminated infection. A small-plaque-producing variant (SP7) was the predominant virus (>99%) in the brain, and a large-plaque-producing variant (LP5) was the predominant virus (>99%) in the lung and gastrointestinal tract.EcoRI andBamHI restriction fragment patterns indicated that SP7 and LP5 are related strains. The large-plaque variants produced plaques similar in size to those produced by HSV-1 KOS. Unlike LP5 or KOS, SP7 was highly cell associated and processing of glycoprotein C and glycoprotein D was limited to precursor forms in infected Vero cells. The large-plaque phenotype from KOS could be transferred into SP7 by cotransfection of plasmids containing the EK or JKEcoRI fragment or a 3-kb plasmid with the UL34.5 gene of HSV-1 KOS together with SP7 DNA. PCR analysis using primers from within the ICP34.5 gene indicated differences for SP7, LP5, and KOS. Sequencing data indicated two sets of deletions in the UL34.5 gene that distinguish SP7 from LP5. Both SP7 and LP5 variants were neurovirulent (lethal following intracranial inoculation of young BALB/c mice); however, the LP5 variant was much less able to cause lethal neuroinvasive disease (footpad inoculation) whereas KOS caused no disease. Passage of SP7 selected for viruses (SLP-5 and SLP-10) which were attenuated for lethal neuroinvasive disease, were not cell-associated, and differed in the UL34.5 gene. UL34.5 from SLP-5 or SLP-10 resembled that of KOS. These findings support a role for UL34.5 in promoting virus egress and for neuroinvasive disease.
CpG-Containing Oligonucleotides Are Efficient Adjuvants for Induction of Protective Antiviral Immune Responses with T-Cell Peptide Vaccines
Authors: Oxenius Annette , Martinic Marianne M. A. , Hengartner Hans , Klenerman Paul 
Published: December 2019

ABSTRACTSynthetic nonmethylated oligonucleotides containing CpG dinucleotides (CpG-ODNs) have been shown to exhibit immunostimulatory activity. CpG-ODNs have the capacity to directly activate B cells, macrophages, and dendritic cells, and we show here that this is reflected by cell surface binding of oligonucleotides to these cell subsets. However, T cells are not directly activated by CpG-ODNs, which correlates with the failure to bind to the T-cell surface. Efficient competition for CpG-induced B-cell activation by non-CpG-containing oligonucleotides suggests that oligonucleotides might bind to an as yet undefined sequence-nonspecific receptor prior to cellular activation. Induction of protective T-cell responses against challenge infection with lymphocytic choriomeningitis virus (LCMV) or with recombinant vaccinia virus expressing the LCMV glycoprotein was achieved by immunizing mice with the immunodominant major histocompatibility complex class I-binding LCMV glycoprotein-derived peptide gp33 together with CpG-ODNs. In these experiments, B cells, potentially serving as CpG-ODN-activated antigen-presenting cells (APCs), were not required for induction of protective immunity since CpG-ODN–gp33-immunized B-cell-deficient mice were equally protected against challenge infection with both viruses. This finding suggested that macrophages and/or dendritic cells were sufficiently activated in vivo by CpG-ODNs to serve as potent APCs for the induction of naive T cells. Furthermore, treatment with CpG-ODN alone induced protection against infection withListeria monocytogenesvia antigen-independent activation of macrophages. These data suggest that CpG activation of macrophages and dendritic cells may provide a critical step in CpG-ODN adjuvant activity.
The Cholesterol Requirement for Sindbis Virus Entry and Exit and Characterization of a Spike Protein Region Involved in Cholesterol Dependence
Authors: Lu Yanping E. , Cassese Todd , Kielian Margaret 
Published: December 2019

ABSTRACT

Semliki Forest virus (SFV) and Sindbis virus (SIN) are enveloped alphaviruses that enter cells via low-pH-triggered fusion in the endocytic pathway and exit by budding from the plasma membrane. Previous studies with cholesterol-depleted insect cells have shown that SFV requires cholesterol in the cell membrane for both virus fusion and efficient exit of progeny virus. An SFV mutant,
srf-3
, shows efficient fusion and exit in the absence of cholesterol due to a single point mutation in the E1 spike subunit, proline 226 to serine. We have here characterized the role of cholesterol in the entry and exit of SIN, an alphavirus quite distantly related to SFV. Growth, primary infection, fusion, and exit of SIN were all dramatically inhibited in cholesterol-depleted cells compared to control cells. Based on sequence differences within the E1 226 region between SFV,
srf-3
, and SIN, we constructed six SIN mutants with alterations within this region and characterized their cholesterol dependence. A SIN mutant,
SGM
, that had the
srf-3
amino acid sequence from E1 position 224 to 235 showed increases of ∼100-fold in infection and ∼250-fold in fusion with cholesterol-depleted cells compared with infection and fusion of wild-type SIN. Pulse-chase analysis demonstrated that
SGM
exit from cholesterol-depleted cells was markedly more efficient than that of wild-type SIN. Thus, similar to SFV, SIN was cholesterol dependent for both virus entry and exit, and the cholesterol dependence of both steps could be modulated by sequences within the E1 226 region.
Intracellular Retention of Hepatitis B Virus Surface Proteins Reduces Interleukin-2 Augmentation after Genetic Immunizations
Authors: Geissler Michael , Bruss Volker , Michalak Sabine , Hockenjos Birgit , Ortmann Dörte , Offensperger Wolf B. , Wands Jack R. , Blum Hubert E. 
Published: December 2019

ABSTRACTWe have previously shown that hepatitis B virus (HBV) surface antigens (HBsAgs) are highly immunogenic after genetic immunization. Compared to the secreted middle HBV surface proteins (MHBs) or small HBV surface proteins (SHBs), the nonsecreted large HBV surface protein (LHBs), however, induced significantly weaker humoral and cellular immune responses that could not be augmented by genetic coimmunizations with cytokine expression plasmids. In order to understand the mechanisms underlying this phenomenon, we examined the effect of coimmunizations with an interleukin-2 (IL-2) DNA expression plasmid on the immunogenicity at the B- and T-cell level of nonsecreted wild-type LHBs, a secreted mutant LHBs, wild-type SHBs, and a nonsecreted mutant SHBs. Coimmunizations of mice with plasmids encoding wild-type SHBs or the secreted mutant LHBs and IL-2 increased anti-HBs responses, helper T-cell proliferative activity and cytotoxic T-lymphocyte killing. By contrast, coimmunizations of plasmids encoding wild-type LHBs or nonsecreted mutant SHBs and IL-2 had no significant effects on immune responses. Interestingly, mice immunized with cytokine expression plasmids 14 days after the injection of the wild-type LHBs plasmid showed augmented immune responses compared to animals simultaneously injected with both expression constructs. Anti-HBs responses in mice injected with plasmids encoding secreted forms of HBsAgs were detectable about 10 days earlier than those in mice immunized with plasmids encoding nonsecreted forms of HBsAgs. Based on these observations, we conclude that cytokines produced by DNA plasmids at the initial site of antigen presentation cannot augment LHBs specific immune responses because LHBs is not produced at high enough levels or is not accessible for uptake by antigen-presenting cells.
Intracellular Trafficking and Localization of the Pseudorabies Virus Us9 Type II Envelope Protein to Host and Viral Membranes
Authors: Brideau A. D. , del Rio T. , Wolffe E. J. , Enquist L. W. 
Published: December 2019

ABSTRACTThe Us9 protein is a phosphorylated membrane protein present in the lipid envelope of pseudorabies virus (PRV) particles in a unique tail-anchored type II membrane topology. In this report, we demonstrate that the steady-state residence of the Us9 protein is in a cellular compartment in or near thetrans-Golgi network (TGN). Through internalization assays with an enhanced green fluorescent protein epitope-tagged Us9 protein, we demonstrate that the maintenance of Us9 to the TGN region is a dynamic process involving retrieval of molecules from the cell surface. Deletion analysis of the cytoplasmic tail reveals that an acidic cluster containing putative phosphorylation sites is necessary for the recycling of Us9 from the plasma membrane. The absence of this cluster results in the relocalization of Us9 to the plasma membrane due to a defect in endocytosis. The acidic motif, however, does not contain signals needed to direct the incorporation of Us9 into viral envelopes. In this study, we also investigate the role of a dileucine endocytosis signal in the Us9 cytoplasmic tail in the recycling and retention of Us9 to the TGN region. Site-directed mutagenesis of the dileucine motif results in an increase in Us9 plasma membrane staining and a partial internalization defect.
Type 1 CD4+T-Cell Help Is Required for Induction of Antipeptide Multispecific Cytotoxic T Lymphocytes by a Lipopeptidic Vaccine in Rhesus Macaques
Authors: Mortara Lorenzo , Gras-Masse Helene , Rommens Corinne , Venet Alain , Guillet Jean-Gerard , Bourgault-Villada Isabelle 
Published: December 2019

ABSTRACTWe have optimized the induction of antiviral cytotoxic T lymphocytes (CTL) in rhesus macaques by a lipopeptide vaccine containing seven peptides from simian immunodeficiency virus (SIV) Nef and Gag proteins and a strong T-helper peptide from tetanus toxoid (TT) that is promiscuous in humans (peptide TT 830-846). Two of the eight immunized macaques showed T-helper (Th) cell proliferation and a specific synthesis of gamma interferon in response to TT 830-846 peptide. They also showed multispecific cytotoxic activity against three to five of the immunizing SIV peptides. These results show the importance of a strong specific type 1 Th response for inducing a multispecific CTL response in vivo, which is essential for the development of an anti-human immunodeficiency virus vaccine.
The Role of Pr55

gag

in the Annealing of tRNA
3
Lys
to Human Immunodeficiency Virus Type 1 Genomic RNA
Authors: Cen Shan , Huang Yue , Khorchid Ahmad , Darlix Jean-Luc , Wainberg Mark A. , Kleiman Lawrence 
Published: December 2019

ABSTRACT

During human immunodeficiency virus type 1 (HIV-1) assembly, the primer tRNA for the reverse transcriptase-catalyzed synthesis of minus-strand strong-stop cDNA, tRNA
3
Lys
, is selectively packaged into the virus and annealed onto the primer binding site on the RNA genome. Annealing of tRNA
3
Lys
in HIV-1 is independent of polyprotein processing and is facilitated in vitro by p7 nucleocapsid (NCp7). We have previously shown that mutations in clusters of basic amino acids flanking the first Cys-His box in NC sequence inhibit annealing of tRNA
3
Lys
in vivo by 70 to 80%. In this report, we have investigated whether these NC mutations act through Pr55

gag

or Pr160

gag-pol

. In vivo placement of tRNA
3
Lys
is measured with total viral RNA as the source of primer tRNA-template in an in vitro reverse transcription assay. Cotransfection of COS cells with a plasmid coding for either mutant Pr55

gag

or mutant Pr160

gag-pol

, and with a plasmid containing HIV-1 proviral DNA, shows that only the NC mutations in Pr55

gag

inhibit tRNA
3
Lys
placement. The NC mutations in Pr55

gag

reduce viral infectivity by 95% and are
trans
-dominant-negative, i.e., they inhibit genomic placement of tRNA
3
Lys
even in the presence of wild-type Pr55

gag

. This dominant phenotype may indicate that the mutant Pr55

gag

is disrupting an ordered Pr55

gag

structure responsible for the annealing of tRNA
3
Lys
to genomic RNA.
The Murine Homolog (Mph) of Human Herpesvirus Entry Protein B (HveB) Mediates Entry of Pseudorabies Virus but Not Herpes Simplex Virus Types 1 and 2
Authors: Shukla Deepak , Rowe Cynthia L. , Dong Yanzhang , Racaniello Vincent R. , Spear Patricia G. 
Published: December 2019

ABSTRACTA mouse member of the immunoglobulin superfamily, originally designated the murine poliovirus receptor homolog (Mph), was found to be a receptor for the porcine alphaherpesvirus pseudorabies virus (PRV). This mouse protein, designated here murine herpesvirus entry protein B (mHveB), is most similar to one of three related human alphaherpesvirus receptors, the one designated HveB and also known as poliovirus receptor-related protein 2. Hamster cells resistant to PRV entry became susceptible upon expression of a cDNA encoding mHveB. Anti-mHveB antibody and a soluble protein composed of the mHveB ectodomain inhibited mHveB-dependent PRV entry. Expression of mHveB mRNA was detected in a variety of mouse cell lines, but anti-mHveB antibody inhibited PRV infection in only a subset of these cell lines, indicating that mHveB is the principal mediator of PRV entry into some mouse cell types but not others. Coexpression of mHveB with PRV gD, but not herpes simplex virus type 1 (HSV-1) gD, inhibited entry activity, suggesting that PRV gD may interact directly with mHveB as a ligand that can cause interference. By analogy with HSV-1, envelope-associated PRV gD probably also interacts directly with mHveB during viral entry.
Detection of Simian Immunodeficiency Virus Gag-Specific CD8+T Lymphocytes in Semen of Chronically Infected Rhesus Monkeys by Cell Staining with a Tetrameric Major Histocompatibility Complex Class I-Peptide Complex
Authors: Jordan Holly L. , Kuroda Marcelo J. , Schmitz Jörn E. , Steenbeke Tavis , Forman Meryl A. , Letvin Norman L. 
Published: December 2019

ABSTRACTEvaluation of human immunodeficiency virus type 1-specific mucosal cytotoxic T lymphocytes can be hampered by limited cell yields from mucosal sites. We sought to characterize virus-specific CD8+T lymphocytes with cytotoxic activity in the male genital tracts of SIVmac-infected rhesus monkeys by using a peptide epitope-specific functional T-cell assay and a tetrameric major histocompatibility complex class I-peptide complex. This tetrameric complex was constructed with the rhesus monkey HLA-A homolog molecule Mamu-A*01 and a dominant-epitope 9-amino-acid fragment of SIVmac Gag (p11C, C-M). The proportion of tetramer-positive CD8+T cells in semen of SIVmac-infected monkeys ranged from 5.9 to 22.0%. By the use of a standard51Cr release assay, these cells were found to have peptide epitope-specific cytolytic activity after in vitro expansion. Four-color flow-cytometric analysis of these seminal tetramer-positive CD8+T cells demonstrated that they express memory-associated (CD62L−CD45RA−) and activation-associated (CD11a+Fas+HLA-DR+) molecules. The present experiments illustrate the power of tetramer technology for evaluating antigen-specific CD8+T lymphocytes in a mucosal tissue compartment.
The Human HLA-A*0201 Allele, Expressed in Hamster Cells, Is Not a High-Affinity Receptor for Adenovirus Type 5 Fiber
Authors: Davison E. , Kirby I. , Elliott T. , Santis G. 
Published: December 2019

ABSTRACTThe coxsackie B virus and adenovirus receptor (CAR) and the major histocompatibility complex (MHC) class I α2 domain have been identified as high-affinity cell receptors for adenovirus type 5 (Ad5) fiber. In this study we show that CAR but not MHC class I allele HLA-A*0201 binds to Ad5 with high affinity when expressed on hamster cells. When both receptors are coexpressed on the cell surface of hamster cells, Ad5 fiber bind to a single high-affinity receptor, which is CAR.
Vaccinia Virus WR Gene A5L Is Required for Morphogenesis of Mature Virions
Authors: Williams Ollie , Wolffe Elizabeth J. , Weisberg Andrea S. , Merchlinsky Michael 
Published: December 2019

ABSTRACT

The vaccinia virus WR A5L open reading frame (corresponding to open reading frame A4L in vaccinia virus Copenhagen) encodes an immunodominant late protein found in the core of the vaccinia virion. To investigate the role of this protein in vaccinia virus replication, we have constructed a recombinant virus, vA5Li, in which the endogenous gene has been deleted and an inducible copy of the A5 gene dependent on isopropyl-β-
d
-thiogalactopyranoside (IPTG) for expression has been inserted into the genome. In the absence of inducer, the yield of infectious virus was dramatically reduced. However, DNA synthesis and processing, viral protein expression (except for A5), and early stages in virion formation were indistinguishable from the analogous steps in a normal infection. Electron microscopy revealed that the major vaccinia virus structural form present in cells infected with vA5Li in the absence of inducer was immature virions. Viral particles were purified from vA5Li-infected cells in the presence and absence of inducer. Both particles contained viral DNA and the full complement of viral proteins, except for A5, which was missing from particles prepared in the absence of inducer. The particles prepared in the presence of IPTG were more infectious than those prepared in its absence. The A5 protein appears to be required for the immature virion to form the brick-shaped intracellular mature virion.
Herpesvirus Ateles Gene Product Tio Interacts with Nonreceptor Protein Tyrosine Kinases
Authors: Albrecht Jens-Christian , Friedrich Ute , Kardinal Christian , Koehn Jadranka , Fleckenstein Bernhard , Feller Stephan M. , Biesinger Brigitte 
Published: December 2019

ABSTRACTHerpesvirus ateles is a gamma-2-herpesvirus which naturally infects spider monkeys (Atelesspp.) and causes malignant lymphoproliferative disorders in various other New World primates. The genomic sequence of herpesvirus ateles strain 73 revealed a close relationship to herpesvirus saimiri, with a high degree of variability within the left terminus of the coding region. A spliced mRNA transcribed from this region was detected in New World monkey T-cell lines transformed by herpesvirus ateles in vitro or derived from T cells of infectedSaguinus oedipus. The encoded viral protein, termed Tio, shows restricted homology to the oncoprotein StpC and to the tyrosine kinase-interacting protein Tip, two gene products responsible for the T-cell-transforming and oncogenic phenotype of herpesvirus saimiri group C strains. Tio was detectable in lysates of the transformed T lymphocytes. Dimer formation was observed after expression of recombinant Tio. After cotransfection, Tio was phosphorylated in vivo by the protein tyrosine kinases Lck and Src and less efficiently by Fyn. Stable complexes of these Src family kinases with the viral protein were detected in lysates of the transfected cells. Binding analyses indicated a direct interaction of Tio with the SH3 domains of Lyn, Hck, Lck, Src, Fyn, and Yes. In addition, tyrosine-phosphorylated Tio bound to the SH2 domains of Lck, Src, or Fyn. Thus, herpesvirus ateles-encoded Tio may contribute to viral T-cell transformation by influencing the function of Src family kinases.
Dengue Virus Structural Differences That Correlate with Pathogenesis
Authors: Leitmeyer Katrin C. , Vaughn David W. , Watts Douglas M. , Salas Rosalba , Villalobos Iris , de Chacon  , Ramos Celso , Rico-Hesse Rebeca 
Published: December 2019

ABSTRACT
The understanding of dengue virus pathogenesis has been hampered by the lack of in vitro and in vivo models of disease. The study of viral factors involved in the production of severe dengue, dengue hemorrhagic fever (DHF), versus the more common dengue fever (DF), have been limited to indirect clinical and epidemiologic associations. In an effort to identify viral determinants of DHF, we have developed a method for comparing dengue type 2 genomes (reverse transcriptase PCR in six fragments) directly from patient plasma. Samples for comparison were selected from two previously described dengue type 2 genotypes which had been shown to be the cause of DF or DHF. When full genome sequences of 11 dengue viruses were analyzed, several structural differences were seen consistently between those associated with DF only and those with the potential to cause DHF: a total of six encoded amino acid charge differences were seen in the prM, E, NS4b, and NS5 genes, while sequence differences observed within the 5′ nontranslated region (NTR) and 3′ NTR were predicted to change RNA secondary structures. We hypothesize that the primary determinants of DHF reside in (i) amino acid 390 of the E protein, which purportedly alters virion binding to host cells; (ii) in the downstream loop (nucleotides 68 to 80) of the 5′ NTR, which may be involved in translation initiation; and (iii) in the upstream 300 nucleotides of the 3′ NTR, which may regulate viral replication via the formation of replicative intermediates. The significance of four amino acid differences in the nonstructural proteins NS4b and NS5, a presumed transport protein and the viral RNA polymerase, respectively, remains unknown. This new approach to the study of dengue virus genome differences should better reflect the true composition of viral RNA populations in the natural host and permit their association with pathogenesis.