bluuebunny/crossref_metadata_2025_split huggingface dataset:
Depletion of Blood-Borne Macrophages Does Not Reduce Demyelination in Mice Infected with a Neurotropic Coronavirus
Authors: Xue Shurong , Sun Ning , Van Rooijen Nico , Perlman Stanley 
Published: December 2019

ABSTRACTMice infected with the neurotropic coronavirus mouse hepatitis virus strain JHM (MHV-JHM) develop a chronic demyelinating disease with symptoms of hindlimb paralysis. Histological examination of the brains and spinal cords of these animals reveals the presence of large numbers of activated macrophages/microglia. In two other experimental models of demyelination, experimental allergic encephalomyelitis and Theiler’s murine encephalomyelitis virus-induced demyelination, depletion of hematogenous macrophages abrogates the demyelinating process. In both of these diseases, early events in the demyelinating process are inhibited by macrophage depletion. From these studies, it was not possible to determine whether infiltrating macrophages were required for late steps in the process, such as myelin removal. In this study, we show that when macrophages are depleted with either unmodified or mannosylated liposomes encapsulating dichloromethylene diphosphate, the amount of demyelination detected in MHV-infected mice is not affected. At a time when these cells were completely depleted from the liver, approximately equivalent numbers of macrophages were present in the spinal cords of control and drug-treated animals. These results suggest that blood-borne macrophages are not required for MHV-induced demyelination and also suggest that other cells, such as perivascular macrophages or microglia, perform the function of these cells in the presence of drug.
Construction and Transposon Mutagenesis in
Escherichia coli
of a Full-Length Infectious Clone of Pseudorabies Virus, an Alphaherpesvirus
Authors: Smith Gregory A. , Enquist Lynn W. 
Published: December 2019

ABSTRACT

A full-length clone of the 142-kb pseudorabies virus (PRV) genome was constructed as a stable F plasmid in
Escherichia coli
. The clone, pBecker1, was colinear with PRV-Becker genomic DNA, lacking detectable rearrangements, deletions, or inversions. The transfection of pBecker1 into susceptible eukaryotic cells resulted in productive viral infection. Virus isolated following transfection was indistinguishable from wild-type virus in a rodent model of infection and spread to retinorecipient regions of the brain following inoculation in the vitreous body of the eye. Mutagenesis of pBecker1 in
E. coli
with a mini-Tn
5
-derived transposon enabled the rapid isolation of insertion mutants, identification of essential viral genes, and simplified construction of viral revertants. The serial passage of a viral insertion mutant demonstrated the transposon insertion to be stable. However, the F-plasmid insertion present in the viral gG locus was found to undergo a spontaneous deletion following transfection into eukaryotic cells. The implications of F-plasmid insertion into the viral genome with regard to phenotype and genomic stability are discussed.
A Lysine-to-Arginine Change Found in Natural Alleles of the Human T-Cell Lymphotropic/Leukemia Virus Type 1 p12
I
Protein Greatly Influences Its Stability
Authors: Trovato Raffaella , Mulloy James C. , Johnson Julie M. , Takemoto Shigeki , de Oliveira Maria Pombo , Franchini Genoveffa 
Published: December 2019

ABSTRACT

The HTLV-1 singly spliced open reading frame I protein, p12
I
, is highly unstable and appears to be necessary for persistent infection in rabbits. Here we demonstrate that p12
I
forms dimers through two putative leucine zipper domains and that its stability is augmented by specific proteasome inhibitors. p12
I
is ubiquitylated, and mutations of its unique carboxy-terminus lysine residue to an arginine greatly enhance its stability. Interestingly, analysis of 53 independent HTLV-1 strains revealed that the natural p12
I
alleles found in ex vivo samples of tropical spastic paraparesis-HTLV-1-associated myelopathy patients contain a Lys at position 88 in some cases, whereas arginine is consistently found at position 88 in HTLV-1 strains from all adult T-cell leukemia-lymphoma (ATLL) cases and healthy carriers studied. This apparent segregation of different alleles in tropical spastic paraparesis-HTLV-associated myelopathy and ATLL or healthy carriers may be relevant in vivo, since p12
I
binds the interleukin-2 receptor β and γ
c
chains, raising the possibility that the two natural alleles might affect differently the regulation of these molecules.
Cell Surface Expression of H2 Antigens on Primary Sensory Neurons in Response to Acute but Not Latent Herpes Simplex Virus Infection In Vivo
Authors: Pereira Rosemarie A. , Simmons Anthony 
Published: December 2019

ABSTRACT

CD8
+
T lymphocytes and class I major histocompatibility complex (MHC-I) molecules profoundly influence the severity of neuronal herpes simplex virus (HSV) infection in experimentally infected mice. Paradoxically, neurons are classically regarded as MHC-I deficient. However, it is shown here that H2-encoded heavy chains (αCs) and their associated light chain, β2 microglobulin, are present on the surfaces of primary sensory neurons recovered from sensory ganglia within 1 to 2 weeks of HSV infection. During this time, some neurons are found to be tightly associated with T cells in vivo. Prior data showed that termination of productive HSV infection in the peripheral nervous system is not dependent on cell-mediated lysis of infected neurons. Consistent with these data, immunogold electron microscopy showed that the density of cell surface H2 on neurons is an order of magnitude lower than on satellite glia, which is predicted to favor a noncytolytic CD8 cell response.
Antiapoptotic and Oncogenic Potentials of Hepatitis C Virus Are Linked to Interferon Resistance by Viral Repression of the PKR Protein Kinase
Authors: Gale Michael , Kwieciszewski Bart , Dossett Michelle , Nakao Haruhisa , Katze Michael G. 
Published: December 2019

ABSTRACTHepatitis C virus (HCV) is prevalent worldwide and has become a major cause of liver dysfunction and hepatocellular carcinoma. The high prevalence of HCV reflects the persistent nature of infection and the large frequency of cases that resist the current interferon (IFN)-based anti-HCV therapeutic regimens. HCV resistance to IFN has been attributed, in part, to the function of the viral nonstructural 5A (NS5A) protein. NS5A from IFN-resistant strains of HCV can repress the PKR protein kinase, a mediator of the IFN-induced antiviral and apoptotic responses of the host cell and a tumor suppressor. Here we examined the relationship between HCV persistence and resistance to IFN therapy. When expressed in mammalian cells, NS5A from IFN-resistant HCV conferred IFN resistance to vesicular stomatitis virus (VSV), which normally is sensitive to the antiviral actions of IFN. NS5A blocked viral double-stranded RNA (dsRNA)-induced PKR activation and phosphorylation of eIF-2α in IFN-treated cells, resulting in high levels of VSV mRNA translation. Mutations within the PKR-binding domain of NS5A restored PKR function and the IFN-induced block to viral mRNA translation. The effects due to NS5A inhibition of PKR were not limited to the rescue of viral mRNA translation but also included a block in PKR-dependent host signaling pathways. Cells expressing NS5A exhibited defective PKR signaling and were refractory to apoptosis induced by exogenous dsRNA. Resistance to apoptosis was attributed to an NS5A-mediated block in eIF-2α phosphorylation. Moreover, cells expressing NS5A exhibited a transformed phenotype and formed solid tumors in vivo. Disruption of apoptosis and tumorogenesis required the PKR-binding function of NS5A, demonstrating that these properties may be linked to the IFN-resistant phenotype of HCV.
Herpes Simplex Virus Latency-Associated Transcript Encodes a Protein Which Greatly Enhances Virus Growth, Can Compensate for Deficiencies in Immediate-Early Gene Expression, and Is Likely To Function during Reactivation from Virus Latency
Authors: Thomas S. K. , Gough G. , Latchman D. S. , R. S.  , Coffin  
Published: December 2019

ABSTRACT
Herpes simplex virus types 1 and 2 (HSV1 and HSV2) enter and reactivate from latency in sensory neurons, although the events governing these processes are little understood. During latency, only the latency-associated transcripts (LATs) are produced. However, although the LAT RNAs were described ≈10 years ago, their function remains ambiguous. Mutations affecting the LATs have minimal effects other than a small reduction in establishment of and reactivation from latency in some cases. Mutations in putative LAT-contained open reading frames (ORFs) have so far shown no effect. The LATs consist of a large species from which smaller (≈2 kb), nuclear, nonlinear LATs which are abundant during latency are spliced. Thus, translation of ORFs in these smaller LATs would not usually be expected to be possible, and if expressed at all, their expression might be tightly regulated. Here we show that deregulated expression of the largest HSV1 2-kb LAT-contained ORF in various cells of neuronal and nonneuronal origin greatly enhances virus growth in a manner specific to HSV1—the HSV1 LAT ORF has no effect on the growth of HSV2. Similar results of enhanced growth were found when the HSV1 LAT ORF was constitutively expressed from within the HSV1 genome. The mechanism of LAT ORF action was strongly suggested to be by substituting for deficiencies in immediate-early (IE) gene expression (particularly ICP0), because deregulated LAT ORF expression, as well as enhancing wild-type virus growth, was also found to allow efficient growth of viruses with mutations in ICP0 or VMW65. Such viruses otherwise exhibit considerable growth defects. IE gene expression deficiencies are often the block to productive infection in nonpermissive cells and are also evident during latency. These results, which we show to be protein- rather than RNA-mediated effects, strongly suggest a function of the tightly regulated expression of a LAT ORF-encoded protein in the reactivation from HSV latency.
Simian Virus 40 Large T Antigen J Domain and Rb-Binding Motif Are Sufficient To Block Apoptosis Induced by Growth Factor Withdrawal in a Neural Stem Cell Line
Authors: Slinskey Alison , Barnes David , Pipas James M. 
Published: December 2019

ABSTRACT

Serum-free mouse embryo (SFME) cells are a neural stem cell line that is dependent upon epidermal growth factor (EGF) for survival. Removal of EGF results in the G
1
arrest and apoptosis of SFME cells. We have shown that the expression of simian virus 40 large T antigen in SFME cells blocks apoptosis and allows cell survival and division in the absence of EGF. Therefore the presence of T antigen abrogates the EGF requirement. The steady-state levels of p53, p21, and mdm-2 do not increase as SFME cells undergo apoptosis upon EGF withdrawal. Furthermore, the amino-terminal 136 amino acids (N136) of T antigen are sufficient to block death and to promote proliferation in the absence of EGF, while the carboxy-terminal fragment (C251–708), which contains the p53 binding site, is unable to block death. Taken together, these data suggest that SFME cells deprived of EGF undergo p53-independent apoptosis. Mutations that disrupt either the J domain or Rb family binding abolish the ability of T antigen to block SFME cell apoptosis and to promote cell growth. We conclude that T antigen must act on one or more members of the Rb family to inhibit SFME cell apoptosis.
A Recombinant Measles Vaccine Virus Expressing Wild-Type Glycoproteins: Consequences for Viral Spread and Cell Tropism
Authors: Johnston Ian C. D. , ter Meulen V. , Schneider-Schaulies Jürgen , Schneider-Schaulies Sibylle 
Published: December 2019

ABSTRACTWild-type, lymphotropic strains of measles virus (MV) and tissue culture-adapted MV vaccine strains possess different cell tropisms. This observation has led to attempts to identify the viral receptors and to characterize the functions of the MV glycoproteins. We have functionally analyzed the interactions of MV hemagglutinin (H) and fusion (F) proteins of vaccine (Edmonston) and wild-type (WTF) strains in different combinations in transfected cells. Cell-cell fusion occurs when both Edmonston F and H proteins are expressed in HeLa or Vero cells. The expression of WTF glycoproteins in HeLa cells did not result in syncytia, yet they fused efficiently with cells of lymphocytic origin. To further investigate the role of the MV glycoproteins in virus cell entry and also the role of other viral proteins in cell tropism, we generated recombinant vaccine MVs containing one or both glycoproteins from WTF. These viruses were viable and grew similarly in lymphocytic cells. Recombinant viruses expressing the WTFH protein showed a restricted spread in HeLa cells but spread efficiently in Vero cells. Parental WTF remained restricted in both cell types. Therefore, not only differential receptor usage but also other cell-specific factors are important in determining MV cell tropism.
Jaagsiekte Sheep Retrovirus Is Necessary and Sufficient To Induce a Contagious Lung Cancer in Sheep
Authors: Palmarini Massimo , Sharp J. Michael , de las Heras Marcelo , Fan Hung 
Published: December 2019

ABSTRACT

Sheep pulmonary adenomatosis (SPA) is a contagious and experimentally transmissible lung cancer of sheep resembling human bronchiolo-alveolar carcinoma. A type D retrovirus, known as jaagsiekte sheep retrovirus (JSRV), has been associated with the etiology of SPA, but its exact role in the induction of the tumor has not been clear due to the lack of (i) a tissue culture system for the propagation of JSRV and (ii) an infectious JSRV molecular clone. To investigate the role of JSRV in the etiology of SPA, we isolated a full-length JSRV proviral clone, pJSRV
21
, from a tumor genomic DNA library derived from a natural case of SPA. pJSRV
21
was completely sequenced and showed open reading frames in agreement with those deduced for the original South African strain of JSRV. In vivo transfection of three newborn lambs by intratracheal inoculation with pJSRV
21
DNA complexed with cationic lipids showed that pJSRV
21
is an infectious molecular clone. Viral DNA was detected in the peripheral blood mononuclear cells (PBMCs) of the transfected animals by a highly sensitive JSRV-U3 heminested PCR at various time points ranging from 2 weeks to 6 months posttransfection. In addition, proviral DNA was detected in the PBMCs, lungs, and mediastinal lymph nodes of two lambs sacrificed 9 months posttransfection, but no macroscopic or histological SPA lesion was induced. We prepared JSRV particles by transient transfection of 293T cells with a JSRV construct (pCMV2JS
21
) in which the upstream U3 was replaced with the cytomegalovirus early promoter. Four newborn lambs were inoculated with JSRV
21
particles produced in this manner, and two of them showed the classical signs of SPA 4 months postinfection. The resulting tumors were positive for JSRV DNA and protein. Thus, JSRV
21
is an infectious and pathogenic molecular clone and is necessary and sufficient to induce sheep pulmonary adenomatosis.
Human MxA Protein Protects Mice Lacking a Functional Alpha/Beta Interferon System against La Crosse Virus and Other Lethal Viral Infections
Authors: Hefti Hans Peter , Frese Michael , Landis Heinrich , Di Paolo Claudio , Aguzzi Adriano , Haller Otto , Pavlovic Jovan 
Published: December 2019

ABSTRACT

The human MxA protein is part of the antiviral state induced by alpha/beta interferon (IFN-α/β). MxA inhibits the multiplication of several RNA viruses in cell culture. However, its antiviral potential in vivo has not yet been fully explored. We have generated MxA-transgenic mice that lack a functional IFN system by crossing MxA-transgenic mice constitutively expressing MxA with genetically targeted (knockout) mice lacking the β subunit of the IFN-α/β receptor (IFNAR-1
−/−
mice). These mice are an ideal animal model to investigate the unique antiviral activity of human MxA in vivo, because they are unable to express other IFN-induced proteins. Here, we show that MxA confers resistance to Thogoto virus, La Crosse virus, and Semliki Forest virus. No Thogoto virus progeny was detectable in MxA-transgenic mice, indicating an efficient block of virus replication at the primary site of infection. In the case of La Crosse virus, MxA restricted invasion of the central nervous system. In contrast, Semliki Forest virus multiplication in the brain was detectable in both MxA-expressing and nonexpressing IFNAR-1
−/−
mice. However, viral titers were clearly reduced in MxA-transgenic mice. Our results demonstrate that MxA does not need the help of other IFN-induced proteins for activity but is a powerful antiviral agent on its own. Moreover, the results suggest that MxA may protect humans from potential fatal infections by La Crosse virus and other viral pathogens.
Tamplicon-7, a Novel T-Lymphotropic Vector Derived from Human Herpesvirus 7
Authors: Romi Hila , Singer Oded , Rapaport Debora , Frenkel Niza 
Published: December 2019

ABSTRACTWe describe the derivation of a novel T-cell-defective virus vector employing the human herpesvirus 7 (HHV-7). The new vector, designated Tamplicon-7, replicates in CD4+T cells. The system is composed of a helper virus and defective virus genomes derived by the replication of the input Tamplicon vector. There are twocis-acting functions required for the replication and packaging of the defective virus genomes in the presence of the helper virus: the viral DNA replication origin and the composite cleavage and packaging signal, which directs the cleavage and packaging of defective virus genomes. Viral DNA replication is compatible with the rolling circle mechanism, producing large head-to-tail concatemers of the Tamplicon vector. Thus, in the presence of the helper virus, the replicated vectors are packaged and secreted into the medium. Furthermore, we have shown that the vector can be employed to express a foreign gene, encoding the green fluorescent protein, in the T cells infected with the HHV-7 helper virus. We predict that the Tamplicon-7 vector might be potentially useful for gene therapy of diseases affecting the human CD4+T cells, including autoimmune diseases, T-cell lymphomas, and AIDS.
Virus-Specific Cytotoxic T Lymphocytes in Human Immunodeficiency Virus Type 1-Infected Chimpanzees
Authors: Santra Sampa , Fultz Patricia N. , Letvin Norman L. 
Published: December 2019

ABSTRACTChimpanzees have been important in studies of human immunodeficiency virus type 1 (HIV-1) pathogenesis and in evaluation of HIV-1 candidate vaccines. However, little information is available about HIV-1-specific cytotoxic T lymphocytes (CTL) in these animals. In the present study, in vitro stimulation of peripheral blood mononuclear cells (PBMC) from infected chimpanzees with HIV-1 Gag peptides was shown to be a sensitive, reproducible method of expanding HIV-1-specific CD8+effector CTL. Of interest, PBMC from two chimpanzees had CTL activity against Gag epitopes also recognized by major histocompatibility complex class I-restricted CTL from HIV-1-infected humans. The use of peptide stimulation will help to clarify the role of CTL in vaccine-mediated protection and HIV-1 disease progression in this important animal model.
Resistance of Ribosomal Protein mRNA Translation to Protein Synthesis Shutoff Induced by Poliovirus
Authors: Cardinali Beatrice , Fiore Lucia , Campioni Nadia , De Dominicis Alessandra , Pierandrei-Amaldi Paola 
Published: December 2019

ABSTRACT

Poliovirus infection induces an overall inhibition of host protein synthesis, although some mRNAs continue to be translated, suggesting different translation requirements for cellular mRNAs. It is known that ribosomal protein mRNAs are translationally regulated and that the phosphorylation of ribosomal protein S6 is involved in the regulation. Here, we report that the translation of ribosomal protein mRNAs resists poliovirus infection and correlates with an increase in p70
s6k
activity and phosphorylation of ribosomal protein S6.
Respiratory Syncytial Virus G and/or SH Protein Alters Th1 Cytokines, Natural Killer Cells, and Neutrophils Responding to Pulmonary Infection in BALB/c Mice
Authors: Tripp Ralph A. , Moore Deborah , Jones Les , Sullender Wayne , Winter Jorn , Anderson Larry J. 
Published: December 2019

ABSTRACTBALB/c mice sensitized to vaccinia virus expressed G protein of respiratory syncytial virus (RSV) develop a Th2-type cytokine response and pulmonary eosinophilia when challenged with live RSV. In this study, BALB/c mice were immunized or challenged with an RSV mutant lacking the G and SH proteins or with DNA vaccines coding for RSV G or F protein. F or G protein DNA vaccines were capable of sensitizing for pulmonary eosinophilia. The absence of the G and/or SH protein in the infecting virus resulted in a consistent increase both in pulmonary natural killer cells and in gamma interferon and tumor necrosis factor expression, as well as, with primary infection, a variable increase in neutrophils and CD11b+cells. The development of pulmonary eosinophilia in formalin-inactivated RSV-vaccinated mice required the presence of the G and/or SH protein in the challenge virus. These data show that G and/or SH protein has a marked impact on the inflammatory and innate immune response to RSV infection.
Human Cytomegalovirus UL36 Protein Is Dispensable for Viral Replication in Cultured Cells
Authors: Patterson Catherine E. , Shenk Thomas 
Published: December 2019

ABSTRACT
Consistent with earlier analyses of human cytomegalovirus UL36 mRNA, we find that the UL36 protein is present throughout infection. In fact, it is delivered to the infected cell as a constituent of the virion. Curiously, much less UL36 protein accumulated in cells infected with the AD169 strain of human cytomegalovirus than in cells infected with the Towne or Toledo strain, and localization of the protein in cells infected with AD169 is strikingly different from that in cell infected with the Towne or Toledo strain. The variation in steady-state level of the proteins results from different stabilities of the proteins. The UL36 proteins from the three viral strains differ by several amino acid substitutions. However, this variability is not responsible for the different half-lives because the AD169 and Towne proteins, which exhibit very different half-lives within infected cells, exhibit the same half-life when introduced into uninfected cells by transfection with expression plasmids. We demonstrate that the UL36 protein is nonessential for growth in cultured cells, and we propose that the ability of the virus to replicate in the absence of UL36 function likely explains the striking strain-specific variation in the half-life and intracellular localization of the protein.
The Herpes Simplex Virus vhs Protein Induces Endoribonucleolytic Cleavage of Target RNAs in Cell Extracts
Authors: Elgadi Mabrouk M. , Hayes Christopher E. , Smiley James R. 
Published: December 2019

ABSTRACT

The herpes simplex virus virion host shutoff (vhs) protein (UL41 gene product) is a component of the HSV virion tegument that triggers shutoff of host protein synthesis and accelerated mRNA degradation during the early stages of HSV infection. Previous studies have demonstrated that extracts from HSV-infected cells and partially purified HSV virions display vhs-dependent RNase activity and that vhs is sufficient to trigger accelerated RNA degradation when expressed as the only HSV protein in an in vitro translation system derived from rabbit reticulocytes. We have used the rabbit reticulocyte translation system to characterize the mode of vhs-induced RNA decay in more detail. We report here that vhs-dependent RNA decay proceeds through endoribonucleolytic cleavage, is not affected by the presence of a 5′ cap or a 3′ poly(A) tail in the RNA substrate, requires Mg
2+
, and occurs in the absence of ribosomes. Intriguingly, sites of preferential initial cleavage were clustered over the 5′ quadrant of one RNA substrate that was characterized in detail. The vhs homologue of pseudorabies virus also induced accelerated RNA decay in this in vitro system.