bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vesicular Stomatitis Virus G Protein Acquires pH-Independent Fusion Activity during Transport in a Polarized Endometrial Cell Line
Authors: Roberts Paul C. , Kipperman Todd , Compans Richard W. 
Published: December 2019

ABSTRACT

Entry of vesicular stomatitis virus (VSV), the prototype member of the rhabdovirus family, occurs by receptor-mediated endocytosis. Subsequently, during traversal through the endosomal compartments, the VSV G protein acquires a low-pH-induced fusion-competent form, allowing for fusion of the viral membrane with endosomal and lysosomal membranes. This fusion event releases genomic RNA into the cytoplasm of the cell. Here we provide evidence that the VSV G protein acquires a fusion-competent form during exocytosis in a polarized endometrial cell line, HEC-1A. VSV infection of HEC-1A cells results in high viral yields and giant cell formation. Syncytium formation is blocked in a concentration-dependent manner by treatment with the lysosomotropic weak base ammonium chloride, which raises intravesicular pH. Virus release is somewhat delayed by treatment with ammonium chloride, but virus yields gradually reach those of control cells. In addition, inhibition of vacuolar H
+
-ATPases by treatment with bafilomycin A1 also inhibited cell to cell fusion without altering virus yields. Virions released from infected HEC cells were themselves not fusion competent, since viral entry required an active H
+
-ATPase and a low-pH-induced conformational change in the viral G protein. Thus, the conformation change leading to fusion competence during exocytotic transport is reversible and reverts during or after release of the virion from the infected cell.
Glycoproteins gM and gN of Pseudorabies Virus Are Dispensable for Viral Penetration and Propagation in the Nervous Systems of Adult Mice
Authors: Masse Marie Jo , Jöns Alice , Dijkstra Johannes M. , Mettenleiter Thomas C. , Flamand Anne 
Published: December 2019

ABSTRACT
Glycoproteins gM and gN are conserved throughout the herpesviruses but are dispensable for viral replication in cell cultures. To assay for a function of these proteins in infection of an animal, deletion mutants of pseudorabies virus lacking gM or gN and corresponding revertants were analyzed for the ability to penetrate and propagate in the nervous systems of adult mice after intranasal inoculation. We demonstrate that neither of the two glycoproteins is required for infection of the nervous systems of mice by pseudorabies virus.
The Open Reading Frame 57 Gene Product of Herpesvirus Saimiri Shuttles between the Nucleus and Cytoplasm and Is Involved in Viral RNA Nuclear Export
Authors: Goodwin Delyth J. , Hall Kersten T. , Stevenson Alex J. , Markham Alex F. , Whitehouse Adrian 
Published: December 2019

ABSTRACT
The herpesvirus saimiri open reading frame (ORF) 57 is homologous to genes identified in all classes of herpesviruses. It has previously been shown to regulate gene expression through a posttranscriptional mechanism. We demonstrate in this report that the expression of the ORF 57 protein leads to the cytoplasmic accumulation of glycoprotein B and capsid mRNAs. We also demonstrate that ORF 57 has the ability to specifically bind viral RNA transcripts. Utilizing an interspecies heterokaryon assay, we show that ORF 57 has the ability to shuttle between the nucleus and the cytoplasm. Furthermore, we show that ORF 57 contains a relatively leucine-rich sequence which shares some homology with nuclear export signals (NES) found in a number of proteins with the ability to shuttle between the nucleus and the cytoplasm. Moreover, we demonstrate that the ORF 57 NES enables the nuclear export of a heterologous protein and that mutation of the conserved leucine residues contained within the ORF 57 NES signal abrogates the ability of the ORF 57 protein to shuttle between the nucleus and cytoplasm. These results suggest that ORF 57 is involved in mediating the nuclear export of viral transcripts.
The Latency-Related Gene of Bovine Herpesvirus 1 Inhibits Programmed Cell Death
Authors: Ciacci-Zanella Janice , Stone Melissa , Henderson Gail , Jones Clinton 
Published: December 2019

ABSTRACT

Although viral gene expression occurs in the peripheral nervous system during acute infection, bovine herpesvirus 1 (BHV-1) gene expression is extinguished, many neurons survive, and latency ensues. The only abundant viral transcript expressed during latency is the latency-related (LR) RNA, which is alternatively spliced in trigeminal ganglia during acute infection (L. Devireddy and C. Jones, J. Virol. 72:7294–7301, 1998). A subset of neurons express a protein encoded by the LR gene and the LR protein (LRP) is associated with cyclin-dependent kinase 2 (Cdk2)/cyclin complexes during productive infection (Y. Jiang, A. Hossain, M. T. Winkler, T. Holt, A. Doster, and C. Jones, J. Virol. 72:8133–8142, 1998). LR gene products inhibit cell cycle progression, perhaps as a result of LRP interacting with Cdk2/cyclin complexes. During acute infection, expression of cyclin A occurs in trigeminal ganglionic neurons (L. M. Schang, A. Hossain, and C. Jones, J. Virol. 70:3807–3814, 1996). Inappropriate expression of G
1
- and S-phase cyclins can initiate programmed cell death (PCD), apoptosis, in neurons, suggesting that LR gene products inhibit PCD. To test this hypothesis, we modified an assay to measure PCD frequency in transiently transfected cells. C
6
-ceramide, fumonisin B
1
(FB
1
), or etoposide was used to initiate PCD following transfection of cells with plasmids expressing LR gene products and the β-galactosidase gene. Transfected cells that survived were quantified by counting β-galactosidase-positive cells. Plasmids that expressed LR gene products promoted survival of monkey kidney (CV-1), human lung (IMR-90), or mouse neuroblastoma (neuro-2A) cells after induction of PCD. Plasmids with termination codons at the beginning of LR open reading frames or deletion of sequences that mediate splicing of LR RNA did not promote cell survival following PCD induction. We hypothesize that LR gene products play a role in promoting survival of postmitotic neurons during acute infection or reactivation.
The Transcriptional Switch of Bacteriophage WΦ, a P2-Related but Heteroimmune Coliphage
Authors: Liu Tao , Haggård-Ljungquist Elisabeth 
Published: December 2019

ABSTRACT

Phage WΦ is a member of the nonlambdoid P2 family of temperate phages. The DNA sequence of the whole early-control region and the
int
and
attP
region of phage WΦ has been determined. The phage integration site was located at 88.6 min of the
Escherichia coli
K-12 map, where a 47-nucleotide sequence was found to be identical in the host and phage genomes. The WΦ Int protein belongs to the Int family of site-specific recombinases, and it seems to have the same arm binding recognition sequence as P2 Int, but the core sequence differs. The transcriptional switch contains two face-to-face promoters, Pe and Pc, and two repressors, C and Cox, controlling Pe and Pc, respectively. The early Pe promoter was found to be much stronger than the Pc promoter. Furthermore, the Pe transcript was shown to interfere with Pc transcription. By site-directed mutagenesis, the binding site of the immunity repressor was located to two direct repeats spanning the Pe promoter. A point mutation in one or the other repeat does not affect repression by C, but when it is included in both, C has no effect on the Pe promoter. The Cox repressor efficiently blocks expression from the Pc promoter, but its DNA recognition sequence was not evident. Most members of the P2 family of phages are able to function as helpers for satellite phage P4, which lacks genes encoding structural proteins and packaging and lysis functions. In this work it is shown that P4 E, known to function as an antirepressor by binding to P2 C, also turns the transcriptional switch of WΦ from the lysogenic to the lytic mode. However, in contrast to P2 Cox, WΦ Cox is unable to activate the P4 Pll promoter.
The Equine Herpesvirus 2 E1 Open Reading Frame Encodes a Functional Chemokine Receptor
Authors: Camarda Grazia , Spinetti Gaia , Bernardini Giovanni , Mair Catherine , Davis-Poynter Nick , Capogrossi Maurizio C. , Napolitano Monica 
Published: December 2019

ABSTRACTSeveral herpesviruses contain open reading frames (ORFs) that encode potential homologs of eucaryotic genes. Equine herpesvirus 2 (EHV-2) is a gammaherpesvirus related to other lymphotropic herpesviruses such as herpesvirus saimiri and Epstein-Barr virus. The E1 ORF of EHV-2, a G protein-coupled receptor homolog, shows 31 to 47% amino acid identity with known CC chemokine receptors. To investigate whether E1 may encode a functional receptor, we cloned the E1 ORF and expressed it in stably transfected cell lines. We report here the identification of the CC chemokine eotaxin as a functional ligand for the EHV-2 E1 receptor. Chemokines are likely to play a role in the regulation of immune functions in equine hosts during EHV-2 infection and, via interaction with E1, may affect viral replication and/or escape from immune responses.
T-Cell Vaccination Alters the Course of Murine Herpesvirus 68 Infection and the Establishment of Viral Latency in Mice
Authors: Liu Luzheng , Usherwood Edward J. , Blackman Marcia A. , Woodland David L. 
Published: December 2019

ABSTRACTDiseases caused by gammaherpesviruses such as Epstein-Barr virus are a major health concern, and there is significant interest in developing vaccines against this class of viral infections. However, the requirements for effective control of gammaherpesvirus infection are only poorly understood. The recent development of the murine herpesvirus MHV-68 model provides an experimental tool to dissect the immune response to gammaherpesvirus infections. In this study, we investigated the impact of priming T cells specific for class I- and class II-restricted epitopes on the acute phase of the infection and the subsequent establishment of latency and infectious mononucleosis. The data show that vaccination with either major histocompatibility complex class I- or class II-restricted T-cell epitopes derived from lytic cycle proteins significantly reduced lung viral titers during the acute infection. Moreover, the peak level of latently infected spleen cells was significantly reduced following vaccination with immunodominant CD8+T-cell epitopes. However, this vaccination approach did not prevent the long-term establishment of latency or the development of the infectious mononucleosis-like syndrome in infected mice. Thus, the virus is able to establish latency efficiently despite strong immunological control of the lytic infection.
Ability of Foot-and-Mouth Disease Virus To Form Plaques in Cell Culture Is Associated with Suppression of Alpha/Beta Interferon
Authors: Chinsangaram Jarasvech , Piccone Maria E. , Grubman Marvin J. 
Published: December 2019

ABSTRACTA genetic variant of foot-and-mouth disease virus lacking the leader proteinase coding region (A12-LLV2) is attenuated in both cattle and swine and, in contrast to wild-type virus (A12-IC), does not spread from the initial site of infection after aerosol exposure of bovines. We have identified secondary cells from susceptible animals, i.e., bovine, ovine, and porcine animals, in which infection with A12-LLV2, in contrast to A12-IC infection, does not produce plaques; this result indicates that this virus cannot spread from the site of initial infection to neighboring cells. Nevertheless, A12-LLV2 can infect these cells, but cytopathic effects and virus yields are significantly reduced compared to those seen with A12-IC infection. Reverse transcription-PCR analysis demonstrates that both A12-LLV2 and A12-IC induce the production of alpha/beta interferon (IFN-α/β) mRNA in host cells. However, only supernatants from A12-LLV2-infected cells have significant antiviral activity. The antiviral activity in supernatants from A12-LLV2-infected embryonic bovine kidney cells is IFN-α/β specific, as assayed with mouse embryonic fibroblast cells with or without IFN-α/β receptors. The results obtained with cell cultures demonstrate that the ability of A12-IC to form plaques is associated with the suppression of IFN-α/β expression and suggest a role for this host factor in the inability of A12-LLV2 to spread and cause disease in susceptible animals.
Molecular Epidemiology and Evolution of Enterovirus 71 Strains Isolated from 1970 to 1998
Authors: Brown Betty A. , Oberste M. Steven , Alexander James P. , Kennett Margery L. , Pallansch Mark A. 
Published: December 2019

ABSTRACT

Enterovirus 71 (EV71) (genus
Enterovirus
, family
Picornaviridae
), a common cause of hand, foot, and mouth disease (HFMD), may also cause severe neurological diseases, such as encephalitis and poliomyelitis-like paralysis. To examine the genetic diversity and rate of evolution of EV71, we have determined and analyzed complete VP1 sequences (891 nucleotides) for 113 EV71 strains isolated in the United States and five other countries from 1970 to 1998. Nucleotide sequence comparisons demonstrated three distinct EV71 genotypes, designated A, B, and C. The genetic variation within genotypes (12% or fewer nucleotide differences) was less than the variation between genotypes (16.5 to 19.7%). Strains of all three genotypes were at least 94% identical to one another in deduced amino acid sequence. The EV71 prototype strain, BrCr-CA-70, isolated in California in 1970, is the sole member of genotype A. Strains isolated in the United States and Australia during the period from 1972 to 1988, a 1994 Colombian isolate, and isolates from a large HFMD outbreak in Malaysia in 1997 are all members of genotype B. Although strains of genotype B continue to circulate in other parts of the world, none have been isolated in the United States since 1988. Genotype C contains strains isolated in 1985 or later in the United States, Canada, Australia, and the Republic of China. The annual rate of evolution within both the B and C genotypes was estimated to be approximately 1.35 × 10
−2
substitutions per nucleotide and is similar to the rate observed for poliovirus. The results indicate that EV71 is a genetically diverse, rapidly evolving virus. Its worldwide circulation and potential to cause severe disease underscore the need for additional surveillance and improved methods to identify EV71 in human disease.
A Conserved Dileucine-Containing Motif in p6

gag

Governs the Particle Association of Vpx and Vpr of Simian Immunodeficiency Viruses SIV
mac
and SIV
agm
Authors: Accola Molly A. , Bukovsky Anatoly A. , Jones Morris S. , Göttlinger Heinrich G. 
Published: December 2019

ABSTRACT

Vpr is a small accessory protein of human and simian immunodeficiency viruses (HIV and SIV) that is specifically incorporated into virions. Members of the HIV-2/SIV
sm
/SIV
mac
lineage of primate lentiviruses also incorporate a related protein designated Vpx. We previously identified a highly conserved L-X-X-L-F sequence near the C terminus of the p6 domain of the Gag precursor as the major virion association motif for HIV-1 Vpr. In the present study, we show that a different leucine-containing motif (D-X-A-X-X-L-L) in the N-terminal half of p6

gag

is required for the incorporation of SIV
mac
Vpx. Similarly, the uptake of SIV
mac
Vpr depended primarily on the D-X-A-X-X-L-L motif. SIV
mac
Vpr was unstable when expressed alone, but its intracellular steady-state levels increased significantly in the presence of wild-type Gag or of the proteasome inhibitor lactacystin. Collectively, our results indicate that the interaction with the Gag precursor via the D-X-A-X-X-L-L motif diverts SIV
mac
Vpr away from the proteasome-degradative pathway. While absent from HIV-1 p6

gag

, the D-X-A-X-X-L-L motif is conserved in both the HIV-2/SIV
sm
/SIV
mac
and SIV
agm
lineages of primate lentiviruses. We found that the incorporation of SIV
agm
Vpr, like that of SIV
mac
Vpx, is absolutely dependent on the D-X-A-X-X-L-L motif, while the L-X-X-L-F motif used by HIV-1 Vpr is dispensable. The similar requirements for the incorporation of SIV
mac
Vpx and SIV
agm
Vpr provide support for their proposed common ancestry.
Interaction of Poliovirus with Its Receptor Affords a High Level of Infectivity to the Virion in Poliovirus Infections Mediated by the Fc Receptor
Authors: Arita Minetaro , Horie Hitoshi , Arita Mineo , Nomoto Akio 
Published: December 2019

ABSTRACTPoliovirus infects susceptible cells through the poliovirus receptor (PVR), which functions to bind virus and to change its conformation. These two activities are thought to be necessary for efficient poliovirus infection. How binding and conformation conversion activities contribute to the establishment of poliovirus infection was investigated. Mouse L cells expressing mouse high-affinity Fcγ receptor molecules were established and used to study poliovirus infection mediated by mouse antipoliovirus monoclonal antibodies (MAbs) (immunoglobulin G2a [IgG2a] subtypes) or PVR-IgG2a, a chimeric molecule consisting of the extracellular moiety of PVR and the hinge and Fc portion of mouse IgG2a. The antibodies and PVR-IgG2a showed the same degree of affinity for poliovirus, but the infectivities mediated by these molecules were different. Among the molecules tested, PVR-IgG2a mediated the infection most efficiently, showing 50- to 100-fold-higher efficiency than that attained with the different MAbs. A conformational change of poliovirus was induced only by PVR-IgG2a. These results strongly suggested that some specific interaction(s) between poliovirus and the PVR is required for high-level infectivity of poliovirus in this system.
The Inhibitory Activity of the AU-Rich RNA Element in the Human Papillomavirus Type 1 Late 3′ Untranslated Region Correlates with Its Affinity for the elav-Like HuR Protein
Authors: Sokolowski Marcus , Furneaux Henry , Schwartz Stefan 
Published: December 2019

ABSTRACT

A 57-nucleotide adenosine- and uridine-rich RNA instability element in the human papillomavirus type 1 late 3′ untranslated region termed
h1
ARE has previously been shown to interact specifically with three nuclear proteins that failed to bind to an inactive mutant RNA. Two of those were identified as the heterogeneous ribonucleoproteins C1 and C2, whereas the third, a 38-kDa, poly(U) binding protein (p38), remained unidentified. Here we show that partially purified p38 reacts with a monoclonal antibody raised against the recently identified elav-like HuR protein, indicating that p38 is the HuR protein. Indeed, recombinant glutathione
S
-transferase (GST)-HuR protein binds specifically to sites within the
h1
ARE. Determination of the apparent

K
d

value of GST-HuR for the
h1
ARE and the inactive mutant thereof revealed that GST-HuR bound with a more than 50-fold-higher affinity to the wild-type sequence. Therefore, the binding affinity of GST-HuR for the wild-type and mutant
h1
AREs correlates with their inhibitory activities in transfected cells, strongly suggesting that the HuR protein is involved in the posttranscriptional regulation of human papillomavirus type 1 late-gene expression.
Bovine Leukemia Virus-Induced Persistent Lymphocytosis in Cattle Does Not Correlate with Increased Ex Vivo Survival of B Lymphocytes
Authors: Dequiedt Franck , Cantor Glenn H. , Hamilton Valerie T. , Pritchard Suzanne M. , Davis William C. , Kerkhofs Pierre , Burny Arsène , Kettmann Richard , Willems Lucas 
Published: December 2019

ABSTRACT
Bovine leukemia virus (BLV) is an oncogenic retrovirus associated with B-cell lymphocytosis, leukemia, and lymphosarcoma in the ovine and bovine species. We have recently reported that in sheep, BLV protects the total population of peripheral blood mononuclear cells (PBMCs) from ex vivo spontaneous apoptosis. This global decrease in the apoptosis rates resulted from both direct and indirect mechanisms which allow extension of cell survival. Although sheep are not natural hosts for BLV, these animals are prone to develop virus-induced leukemia at very high frequencies. Most infected cattle, however, remain clinically healthy. This difference in the susceptibilities to development of leukemia in these two species might be related to alterations of the apoptotic processes. Therefore, we designed this study to unravel the mechanisms of programmed cell death in cattle. We have observed that PBMCs from persistently lymphocytotic BLV-infected cows were more susceptible to spontaneous ex vivo apoptosis than cells from uninfected or aleukemic animals. These higher apoptosis rates were the consequence of an increased proportion of B cells exhibiting lower survival abilities. About one-third of the BLV-expressing cells did not survive the ex vivo culture conditions, demonstrating that viral expression is not strictly associated with cell survival in cattle. Surprisingly, culture supernatants from persistently lymphocytotic cows exhibited efficient antiapoptotic properties on both uninfected bovine and uninfected ovine cells. It thus appears that indirect inhibition of cell death can occur even in the presence of high apoptosis rates. Together, these results demonstrate that the protection against spontaneous apoptosis associated with BLV is different in cattle and in sheep. The higher levels of ex vivo apoptosis occurring in cattle might indicate a decreased susceptibility to development of leukemia in vivo.
Detection and Sequence Analysis of Hepatitis B Virus Integration in Peripheral Blood Mononuclear Cells
Authors: Laskus Tomasz , Radkowski Marek , Wang Lian-Fu , Nowicki Marek , Rakela Jorge 
Published: December 2019

ABSTRACT
A PCR-based technique was used to detect hepatitis B virus (HBV) integration in peripheral blood mononuclear cells from patients with chronic hepatitis B. Integrated HBV DNA sequences, with virus-cell junctions located in the cohesive region between direct repeat 1 (DR1) and DR2, were found in 2 of 10 studied patients.
Mutational Analysis of Vaccinia Virus Nucleoside Triphosphate Phosphohydrolase I, a DNA-Dependent ATPase of the DExH Box Family
Authors: Martins Alexandra , Gross Christian H. , Shuman Stewart 
Published: December 2019

ABSTRACT

Vaccinia virus nucleoside triphosphate phosphohydrolase I (NPH-I) is a DNA-dependent ATPase that serves as a transcription termination factor during viral mRNA synthesis. NPH-I is a member of the DExH box family of nucleic acid-dependent nucleoside triphosphatases (NTPases), which is defined by the presence of several conserved sequence motifs. We have assessed the contributions of individual amino acids (underlined) in motifs I (GxG
KT
), II (
DE
x
HN
), III (
S
A
T
), and VI (
Q
xx
GR
xx
R
) to ATP hydrolysis by performing alanine scanning mutagenesis. Significant decrements in ATPase activity resulted from mutations at nine positions: Lys-61 and Thr-62 (motif I); Asp-141, Glu-142, His-144, and Asn-145 (motif II); and Gln-472, Arg-476, and Arg-479 (motif VI). Structure-function relationships at each of these positions were clarified by introducing conservative substitutions and by steady-state kinetic analysis of the mutant enzymes. Comparison of our findings for NPH-I with those of mutational studies of other DExH and DEAD box proteins underscores similarities as well as numerous disparities in structure-activity relationships. We conclude that the functions of the conserved amino acids of the NTPase motifs are context dependent.