bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acute and Persistent Infection of Human Neural Cell Lines by Human Coronavirus OC43
Authors: Arbour Nathalie , Côté Geneviève , Lachance Claude , Tardieu Marc , Cashman Neil R. , Talbot Pierre J. 
Published: December 2019

ABSTRACT
Human coronaviruses (HuCV) are recognized respiratory pathogens. Data accumulated by different laboratories suggest their neurotropic potential. For example, primary cultures of human astrocytes and microglia were shown to be susceptible to an infection by the OC43 strain of HuCV (A. Bonavia, N. Arbour, V. W. Yong, and P. J. Talbot, J. Virol. 71:800–806, 1997). We speculate that the neurotropism of HuCV will lead to persistence within the central nervous system, as was observed for murine coronaviruses. As a first step in the verification of our hypothesis, we have characterized the susceptibility of various human neural cell lines to infection by HuCV-OC43. Viral antigen, infectious virus progeny, and viral RNA were monitored during both acute and persistent infections. The astrocytoma cell lines U-87 MG, U-373 MG, and GL-15, as well as neuroblastoma SK-N-SH, neuroglioma H4, oligodendrocytic MO3.13, and the CHME-5 immortalized fetal microglial cell lines, were all susceptible to an acute infection by HuCV-OC43. Viral antigen and RNA and release of infectious virions were observed during persistent HuCV-OC43 infections (∼130 days of culture) of U-87 MG, U-373 MG, MO3.13, and H4 cell lines. Nucleotide sequences of RNA encoding the putatively hypervariable viral S1 gene fragment obtained after 130 days of culture were compared to that of initial virus input. Point mutations leading to amino acid changes were observed in all persistently infected cell lines. Moreover, an in-frame deletion was also observed in persistently infected H4 cells. Some point mutations were observed in some molecular clones but not all, suggesting evolution of the viral population and the emergence of viral quasispecies during persistent infection of H4, U-87 MG, and MO3.13 cell lines. These results are consistent with the potential persistence of HuCV-OC43 in cells of the human nervous system, accompanied by the production of infectious virions and molecular variation of viral genomic RNA.
A Herpesvirus Ribosome-Associated, RNA-Binding Protein Confers a Growth Advantage upon Mutants Deficient in a GADD34-Related Function
Authors: Mulvey Matthew , Poppers Jeremy , Ladd Alison , Mohr Ian 
Published: December 2019

ABSTRACT

The herpes simplex virus type 1 γ34.5 gene product and the cellular GADD34 protein both contain similar domains that can regulate the activity of eukaryotic initiation factor 2 (eIF2), a critical translation initiation factor. Viral mutants that lack the GADD34-related function grow poorly on a variety of malignant human cells, as activation of the cellular PKR kinase leads to the accumulation of inactive, phosphorylated eIF2 at late times postinfection. Termination of translation prior to the completion of the viral reproductive cycle leads to impaired growth. Extragenic suppressors that regain the ability to synthesize proteins efficiently in the absence of the viral GADD34-related function have been isolated. These suppressor alleles are dominant in
trans
and affect the steady-state accumulation of several viral mRNA species. We demonstrate that deregulated expression of Us11, a virus-encoded RNA-binding, ribosome-associated protein is necessary and sufficient to confer a growth advantage upon viral mutants that lack a GADD34-related function. Ectopic expression of Us11 reduces the accumulation of the activated cellular PKR kinase and allows for sustained protein synthesis. Thus, an RNA-binding, ribosome-associated protein (Us11) and a GADD34-related protein (γ34.5) both function in a signal pathway that regulates translation by modulating eIF2 phosphorylation.
The Equine Herpesvirus 1 U
S
2 Homolog Encodes a Nonessential Membrane-Associated Virion Component
Authors: Meindl Alexandra , Osterrieder Nikolaus 
Published: December 2019

ABSTRACT

Experiments were conducted to analyze the equine herpesvirus 1 (EHV-1) gene 68 product which is encoded by the EHV-1 U
S
2 homolog. An antiserum directed against the amino-terminal 206 amino acids of the EHV-1 U
S
2 protein specifically detected a protein with an
M
r
of 34,000 in cells infected with EHV-1 strain RacL11. EHV-1 strain Ab4 encodes a 44,000-
M
r
U
s
2 protein, whereas vaccine strain RacH, a high-passage derivative of RacL11, encodes a 31,000-
M
r
U
s
2 polypeptide. Irrespective of its size, the U
S
2 protein was incorporated into virions. The EHV-1 U
S
2 protein localized to membrane and nuclear fractions of RacL11-infected cells and to the envelope fraction of purified virions. To monitor intracellular trafficking of the protein, the green fluorescent protein (GFP) was fused to the carboxy terminus of the EHV-1 U
S
2 protein or to a truncated U
S
2 protein lacking a stretch of 16 hydrophobic amino acids at the extreme amino terminus. Both fusion proteins were detected at the plasma membrane and accumulated in the vicinity of nuclei of transfected cells. However, trafficking of either GFP fusion protein through the secretory pathway could not be demonstrated, and the EHV-1 U
S
2 protein lacked detectable N- and O-linked carbohydrates. Consistent with the presence of the U
S
2 protein in the viral envelope and plasma membrane of infected cells, a U
S
2-negative RacL11 mutant (L11ΔU
S
2) exhibited delayed penetration kinetics and produced smaller plaques compared with either wild-type RacL11 or a U
S
2-repaired virus. After infection of BALB/c mice with L11ΔU
S
2, reduced pathogenicity compared with the parental RacL11 virus and the repaired virus was observed. It is concluded that the EHV-1 U
S
2 protein modulates virus entry and cell-to-cell spread and appears to support sustained EHV-1 replication in vivo.
Will Multiple Coreceptors Need To Be Targeted by Inhibitors of Human Immunodeficiency Virus Type 1 Entry?
Authors: Zhang Yi-jun , Moore John P. 
Published: December 2019

ABSTRACTDespite being able to use the Bonzo coreceptor as efficiently as CCR5 in transfected cells, pediatric human immunodeficiency virus type 1 isolate P6 was unable to replicate in peripheral blood mononuclear cells (PBMC) lacking the CCR5 receptor. Furthermore, its replication in wild-type PBMC was completely inhibited by inhibitors of CCR5-mediated entry. Similarly, maternal isolate M6 could use CCR5, CXCR4, Bonzo, and other coreceptors in transfected cells but was completely sensitive to inhibitors of CCR5- and CXCR4-mediated entry when grown in PBMC. The ability of these viruses to use coreceptors in addition to CCR5 and CXCR4 in vitro was, therefore, irrelevant to their drug sensitivity in primary cells. We argue that CCR5 and CXCR4 should remain the primary targets for antiviral drug development, pending strong evidence to the contrary.
Direct Evidence that the Poly(A) Tail of Influenza A Virus mRNA Is Synthesized by Reiterative Copying of a U Track in the Virion RNA Template
Authors: Poon Leo L. M. , Pritlove David C. , Fodor Ervin , Brownlee George G. 
Published: December 2019

ABSTRACT
The poly(A) tail of influenza virus mRNA is thought to be synthesized by reiterative copying of the U track near the 5′ end of the virion RNA template. This has been widely accepted as a plausible hypothesis, but until now there has been no direct experimental evidence for it. Here, we report such direct evidence based on the fact that (i) replacing the U track with an A track directs synthesis of products with poly(U) tails, both in vitro and in vivo, and (ii) interrupting the U track abolishes polyadenylation in vitro.
Infectious Pancreatic Necrosis Virus: Identification of a VP3-Containing Ribonucleoprotein Core Structure and Evidence for O-Linked Glycosylation of the Capsid Protein VP2
Authors: Hjalmarsson Anna , Carlemalm Eric , Everitt Einar 
Published: December 2019

ABSTRACT

Virions of infectious pancreatic necrosis virus (IPNV) were completely disintegrated upon dialysis against salt-free buffers. Direct visualization of such preparations by electron microscopy revealed 5.0- to 6.5-nm-thick entangled filaments. By using a specific colloidal gold immunolabeling technique, these structures were shown to contain the viral protein VP3. Isolation by sucrose gradient centrifugation of the filaments, followed by serological analysis, demonstrated that the entire VP3 content of the virion was recovered together with the radiolabeled genomic material forming the unique threadlike ribonucleoprotein complexes. In a sensitive blotting assay, the outer capsid component of IPNV, i.e., the major structural protein VP2, was shown to specifically bind lectins recognizing sugar moieties of
N
-acetylgalactosamine, mannose, and fucose. Three established metabolic inhibitors of N-linked glycosylation did not prevent addition of sugar residues to virions, and enzymatic deglycosylation of isolated virions using
N
-glycosidase failed to remove sugar residues of VP2 recognized by lectins. However, gentle alkaline β elimination clearly reduced the ability of lectins to recognize VP2. These results suggest that the glycosylation of VP2 is of the O-linked type when IPNV is propagated in RTG-2 cells.
Highly Potent RANTES Analogues either Prevent CCR5-Using Human Immunodeficiency Virus Type 1 Infection In Vivo or Rapidly Select for CXCR4-Using Variants
Authors: Mosier Donald E. , Picchio Gastón R. , Gulizia Richard J. , Sabbe Rebecca , Poignard Pascal , Picard Laurent , Offord Robin E. , Thompson Darren A. , Wilken Jill 
Published: December 2019

ABSTRACT

The natural ligands for the CCR5 chemokine receptor, macrophage inflammatory protein 1α (MIP-1α), MIP-1β, and RANTES (regulated on T-cell activation, normal T-cell expressed and secreted), are known to inhibit human immunodeficiency virus (HIV) entry, and N-terminally modified RANTES analogues are more potent than native RANTES in blocking infection. However, potent CCR5 blocking agents may select for HIV-1 variants that use alternative coreceptors at less than fully inhibitory concentrations. In this study, two N-terminal chemical modifications of RANTES produced by total synthesis, aminooxypentane (AOP)-RANTES[2-68] and
N
-nonanoyl (NNY)-RANTES[2-68], were tested for their ability to prevent HIV-1 infection and to select for coreceptor switch variants in the human peripheral blood lymphocyte-SCID mouse model. Mice were infected with a CCR5-using HIV-1 isolate that requires only one or two amino acid substitutions to use CXCR4 as a coreceptor. Even though it achieved lower circulating concentrations than AOP-RANTES (75 to 96 pM as opposed to 460 pM under our experimental conditions), NNY-RANTES was more effective in preventing HIV-1 infection. However, in a subset of treated mice, these levels of NNY-RANTES rapidly selected viruses with mutations in the V3 loop of envelope that altered coreceptor usage. These results reinforce the case for using agents that block all significant HIV-1 coreceptors for effective therapy.
Characterization of an E1A-CBP Interaction Defines a Novel Transcriptional Adapter Motif (TRAM) in CBP/p300
Authors: O’Connor Mark J. , Zimmermann Holger , Nielsen Søren , Bernard Hans-Ulrich , Kouzarides Tony 
Published: December 2019

ABSTRACT
The adenovirus E1A protein subverts cellular processes to induce mitotic activity in quiescent cells. Important targets of E1A include members of the transcriptional adapter family containing CBP/p300. Competition for CBP/p300 binding by various cellular transcription factors has been suggested as a means of integrating different signalling pathways and may also represent a potential mechanism by which E1A manipulates cell fate. Here we describe the characterization of the interaction between E1A and the C/H3 region of CBP. We define a novel conserved 12-residue transcriptional adapter motif (TRAM) within CBP/p300 that represents the binding site for both E1A and numerous cellular transcription factors. We also identify a sequence (FPESLIL) within adenovirus E1A that is required to bind the CBP TRAM. Furthermore, an E1A peptide containing the FPESLIL sequence is capable of preventing the interaction between CBP and TRAM-binding transcription factors, such as p53, E2F, and TFIIB, thus providing a molecular model for E1A action. As an in vivo demonstration of this model, we used a small region of CBP containing a functional TRAM that can bind to the p53 protein. The CBP TRAM binds p53 sequences targeted by the cellular regulator MDM2, and we demonstrate that an MDM2-p53 interaction can be disrupted by the CBP TRAM, leading to stabilization of cellular p53 levels and the activation of p53-dependent transcription. Transcriptional activation of p53 by the CBP TRAM is abolished by wild-type E1A but not by a CBP-binding-deficient E1A mutant.
Identification of a Novel GC-Rich 113-Nucleotide Region To Complete the Circular, Single-Stranded DNA Genome of TT Virus, the First Human Circovirus
Authors: Miyata Hironori , Tsunoda Hiroaki , Kazi Aslamuzzaman , Yamada Akio , Khan Mohammed Ali , Murakami Jun , Kamahora Toshio , Shiraki Kazuo , Hino Shigeo 
Published: December 2019

ABSTRACT
The sequence data (H. Okamoto et al., Hepatol. Res. 10:1–16, 1998) of a newly discovered single-stranded DNA virus, TT virus (TTV), showed that it did not have the terminal structure typical of a parvovirus. Elucidation of the complete genome structure was necessary to understand the nature of TTV. We obtained a 1.0-kb amplified product from serum samples of four TTV carriers by an inverted, nested long PCR targeted for nucleotides (nt) 3025 to 3739 and 1 to 216 of TTV. The sequence of a clone obtained from serum sample TA278 was compared with those registered in GenBank. The complete circular TTV genome contained a novel sequence of 113 nt (nt 3740 to 3852 [=0]) in between the known 3′- and 5′-end arms, forming a 117-nt GC-rich stretch (GC content, 90.6% at nt 3736 to 3852). We found a 36-nt stretch (nt 3816 to 3851) with an 80.6% similarity to chicken anemia virus (CAV) (nt 2237 to 2272 of M55918), a vertebrate circovirus. A putative SP-1 site was located at nt 3834 to 3839, followed by a TATA box at nt 85 to 90, the first initiation codon of a putative VP2 at nt 107 to 109, the termination codon of a putative VP1 at nt 2899 to 2901, and a poly(A) signal at nt 3073 to 3078. The arrangement was similar to that of CAV. Furthermore, several AP-2 and ATF/CREB binding sites and an NF-κB site were arranged around the GC-rich region in both TTV and CAV. The data suggested that TTV is circular and similar to CAV in its genomic organization, implying that TTV is the first human circovirus.
Retroviral Insertions inEvi12, a Novel Common Virus Integration Site Upstream ofTra1/Grp94, Frequently Coincide with Insertions in the Gene Encoding the Peripheral Cannabinoid ReceptorCnr2
Authors: Valk Peter J. M. , Vankan Yolanda , Joosten Marieke , Jenkins Nancy A. , Copeland Neal G. , Löwenberg Bob , Delwel Ruud 
Published: December 2019

ABSTRACTThe common virus integration site (VIS)Evi11was recently identified within the gene encoding the hematopoietic G-protein-coupled peripheral cannabinoid receptorCnr2(also referred to asCb2). Here we show thatCnr2is a frequent target (12%) for insertion of Cas-Br-M murine leukemia virus (MuLV) in primary tumors in NIH/Swiss mice. Multiple provirus insertions inEvi11were cloned and shown to be located within the 3′ untranslated region of the candidate proto-oncogeneCnr2. These results suggest that proviral insertion in theCnr2gene is an important step in Cas-Br-M MuLV-induced leukemogenesis in NIH/Swiss mice. To isolateEvi11/Cnr2collaborating proto-oncogenes, we searched for novel common VISs in the Cas-Br-M MuLV-induced primary tumors and identified a novel frequent common VIS,Evi12(14%). Interestingly, 54% of theEvi11/Cnr2-rearranged primary tumors contained insertions inEvi12as well, which suggests cooperative action of the target genes in these two common VISs in leukemogenesis. By interspecific backcross analysis it was shown thatEvi12resides on mouse chromosome 10 in a region that shares homology with human chromosomes 12q and 19p. Sequence analysis demonstrated thatEvi12is located upstream of the gene encoding the molecular chaperoneTra1/Grp94, which was previously mapped to mouse chromosome 10 and human chromosome 12q22–24. Thus,Tra1/Grp94is a candidate target gene for retroviral activation or inactivation inEvi12. However, Northern and Western blot analyses did not provide evidence that proviral insertion had altered the expression ofTra1/Grp94. Additional studies are required to determine whetherTra1/Grp94or another candidate proto-oncogene inEvi12is involved in leukemogenesis.
Opposite Effects of SDF-1 on Human Immunodeficiency Virus Type 1 Replication
Authors: Maréchal Valérie , Arenzana-Seisdedos Fernando , Heard Jean-Michel , Schwartz Olivier 
Published: December 2019

ABSTRACTThe α-chemokine SDF-1 binds CXCR4, a coreceptor for human immunodeficiency virus type 1 (HIV-1), and inhibits viral entry mediated by this receptor. Since chemokines are potent chemoattractants and activators of leukocytes, we examined whether the stimulation of HIV target cells by SDF-1 affects the replication of virus with different tropisms. We observed that SDF-1 inhibited the entry of X4 strains and increased the infectivity of particles bearing either a CCR5-tropic HIV-1 envelope or a vesicular stomatitis virus G envelope. In contrast to the inhibitory effect of SDF-1 on X4 strains, which is at the level of entry, the stimulatory effect does not involve envelope-receptor interactions or proviral DNA synthesis. Rather, we observed an increased ability of Tat to transactivate the HIV-1 long terminal repeat in the presence of the chemokine. Therefore, the effects of SDF-1 on the HIV-1 life cycle can be multiple and opposite, including both an inhibition of viral entry and a stimulation of proviral gene expression.
Enrichment of a Precore-Minus Mutant of Duck Hepatitis B Virus in Experimental Mixed Infections
Authors: Zhang Yong-Yuan , Summers Jesse 
Published: December 2019

ABSTRACTA precore-deficient mutant of duck hepatitis B virus (DHBV) produced by site-directed mutagenesis was tested for its ability to compete with wild-type virus in a mixed infection of 3-day-old ducklings. The mutation was shown to produce acis-acting defect, resulting in a replication rate that was about one-half that of wild-type virus. Accordingly, wild-type virus was rapidly selected during the spread of infection. During the chronic phase of the infection, however, two selection patterns were seen. In 4 of 10 ducks, the wild-type virus slowly replaced the precore mutant. In another four ducks, the precore mutant virus slowly replaced the wild-type virus. In the remaining two ducklings, ratios of wild-type and precore mutant virus fluctuated, with wild-type virus slowly predominating. The replacement of wild-type virus was not due to the emergence of a rapidly replicating variant of the precore mutant, since genomes cloned from the infected ducks retained their original replication defect. Replacement of wild-type virus, however, correlated with elevated anti-core antibody titers, which continued to increase with time. The selection of a precore-negative strain of DHBV may be analogous to the selection for precore mutants of HBV during chronic hepatitis in humans.
Shared Usage of the Chemokine Receptor CXCR4 by Primary and Laboratory-Adapted Strains of Feline Immunodeficiency Virus
Authors: Richardson Jennifer , Pancino Gianfranco , Merat Rastine , Leste-Lasserre Thierry , Moraillon Anne , Schneider-Mergener Jens , Alizon Marc , Sonigo Pierre , Heveker Nikolaus 
Published: December 2019

ABSTRACTStrains of the feline immunodeficiency virus (FIV) presently under investigation exhibit distinct patterns of in vitro tropism. In particular, the adaptation of FIV for propagation in Crandell feline kidney (CrFK) cells results in the selection of strains capable of forming syncytia with cell lines of diverse species origin. The infection of CrFK cells by CrFK-adapted strains appears to require the chemokine receptor CXCR4 and is inhibited by its natural ligand, stromal cell-derived factor 1α (SDF-1α). Here we found that inhibitors of CXCR4-mediated infection by human immunodeficiency virus type I (HIV-1), such as the bicyclam AMD3100 and short peptides derived from the amino-terminal region of SDF-1α, also blocked infection of CrFK by FIV. Nevertheless, we observed differences in the ranking order of the peptides as inhibitors of FIV and HIV-1 and showed that such differences are related to the species origin of CXCR4 and not that of the viral envelope. These results suggest that, although the envelope glycoproteins of FIV and HIV-1 are substantially divergent, FIV and HIV-1 interact with CXCR4 in a highly similar manner. We have also addressed the role of CXCR4 in the life cycle of primary isolates of FIV. Various CXCR4 ligands inhibited infection of feline peripheral blood mononuclear cells (PBMC) by primary FIV isolates in a concentration-dependent manner. These ligands also blocked the viral transduction of feline PBMC by pseudotyped viral particles when infection was mediated by the envelope glycoprotein of a primary FIV isolate but not by the G protein of vesicular stomatitis virus, indicating that they act at an envelope-mediated step and presumably at viral entry. These findings strongly suggest that primary and CrFK-adapted strains of FIV, despite disparate in vitro tropisms, share usage of CXCR4.
Replicative Fitness of Protease Inhibitor-Resistant Mutants of Human Immunodeficiency Virus Type 1
Authors: Martinez-Picado Javier , Savara Anu V. , Sutton Lorraine , D’Aquila Richard T. 
Published: December 2019

ABSTRACT
The relative replicative fitness of human immunodeficiency virus type 1 (HIV-1) mutants selected by different protease inhibitors (PIs) in vivo was determined. Each mutant was compared to wild type (WT), NL4-3, in the absence of drugs by several methods, including clonal genotyping of cultures infected with two competing viral variants, kinetics of viral antigen production, and viral infectivity/virion particle ratios. A nelfinavir-selected protease D30N substitution substantially decreased replicative capacity relative to WT, while a saquinavir-selected L90M substitution moderately decreased fitness. The D30N mutant virus was also outcompeted by the L90M mutant in the absence of drugs. A major natural polymorphism of the HIV-1 protease, L63P, compensated well for the impairment of fitness caused by L90M but only slightly improved the fitness of D30N. Multiply substituted indinavir-selected mutants M46I/L63P/V82T/I84V and L10R/M46I/L63P/V82T/I84V were just as fit as WT. These results indicate that the mutations which are usually initially selected by nelfinavir and saquinavir, D30N and L90M, respectively, impair fitness. However, additional mutations may improve the replicative capacity of these and other drug-resistant mutants. Hypotheses based on the greater fitness impairment of the nelfinavir-selected D30N mutant are suggested to explain observations that prolonged responses to delayed salvage regimens, including alternate PIs, may be relatively common after nelfinavir failure.