bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synaptic Pathology in Borna Disease Virus Persistent Infection
Authors: Gonzalez-Dunia Daniel , Watanabe Michiko , Syan Sylvie , Mallory Margaret , Masliah Eliezer , Carlos de la Torre Juan 
Published: July 2002

ABSTRACT
Borna disease virus (BDV) infection of newborn rats leads to a persistent infection of the brain, which is associated with behavioral and neuroanatonomical abnormalities. These disorders occur in the absence of lymphoid cell infiltrates, and BDV-induced cell damage is restricted to defined brain areas. To investigate if damage to synaptic structures anteceded neuronal loss in BDV neonatally infected rats, we analyzed at different times postinfection the expression levels of growth-associated protein 43 and synaptophysin, two molecules involved in neuroplasticity processes. We found that BDV induced a progressive and marked decrease in the expression of these synaptic markers, which was followed by a significant loss of cortical neurons. Our findings suggest that BDV persistent infection interferes with neuroplasticity processes in specific cell populations. This, in turn, could affect the proper supply of growth factors and other molecules required for survival of selective neuronal populations within the cortex and limbic system structures.
Role of the Cytoplasmic Tail of Pseudorabies Virus Glycoprotein E in Virion Formation
Authors: Brack Alexandra R. , Klupp Barbara G. , Granzow Harald , Tirabassi Rebecca , Enquist Lynn W. , Mettenleiter Thomas C. 
Published: July 2002

ABSTRACT

Glycoproteins M (gM), E (gE), and I (gI) of pseudorabies virus (PrV) are required for efficient formation of mature virions. The simultaneous absence of gM and the gE/gI complex results in severe deficiencies in virion morphogenesis and cell-to-cell spread, leading to drastically decreased virus titers and a small-plaque phenotype (A. Brack, J. Dijkstra, H. Granzow, B. G. Klupp, and T. C. Mettenleiter, J. Virol. 73:5364–5372, 1999). Serial passaging in noncomplementing cells of a virus mutant unable to express gM, gE, and gI resulted in a reversion of the small-plaque phenotype and restoration of infectious virus formation to the level of a gM
−
mutant. Genetic analyses showed that reversion of the phenotype was accompanied by a genomic rearrangement which led to the fusion of a portion of the gE gene encoding the cytoplasmic domain to the 3′ end of the glycoprotein D gene, resulting in expression of a chimeric gD-gE protein. Since this indicated that the intracytoplasmic domain of gE was responsible for the observed phenotypic alterations, the UL10 (gM) gene was deleted in a PrV mutant, PrV-107, which specifically lacked the cytoplasmic tail of gE. Regarding one-step growth, plaque size, and virion formation as observed under the electron microscope, the mutant lacking gM and the gE cytoplasmic tail proved to be very similar to the gE/I/M triple mutant. Thus, our data indicate that it is the cytoplasmic tail of gE which is responsible for the observed phenotypic effects in conjunction with deletion of gM. We hypothesize that the cytoplasmic domain of gE specifically interacts with components of the capsid and/or tegument, leading to efficient secondary envelopment of intracytoplasmic capsids.
Mutagenic Analysis of the 5′ Arm of the Influenza A Virus Virion RNA Promoter Defines the Sequence Requirements for Endonuclease Activity
Authors: Leahy Michael B. , Pritlove David C. , Poon Leo L. M. , Brownlee George G. 
Published: July 2002

ABSTRACT

Short synthetic influenza virus-like RNAs derived from influenza virus promoter sequences were examined for their ability to stimulate the endonuclease activity of recombinant influenza virus polymerase complexes in vitro, an activity that is required for the cap-snatching activity of primers from host pre-mRNA. An extensive set of point mutants of the 5′ arm of the influenza A virus viral RNA (vRNA) was constructed to determine the
cis
-acting elements which influenced endonuclease activity. Activity was found to be dependent on three features of the conserved vRNA termini: (i) the presence of the 5′ hairpin loop structure, (ii) the identity of residues at positions 5 and 10 bases from the 5′ terminus, and (iii) the presence of base pair interactions between the 5′ and 3′ segment ends. Further experiments discounted a role for the vRNA U track in endonuclease activation. This study represents the first mutagenic analysis of the influenza virus promoter with regard to endonuclease activity.
Identification of the Regions of Fv1 Necessary for Murine Leukemia Virus Restriction
Authors: Bishop Kate N. , Bock Michael , Towers Greg , Stoye Jonathan P. 
Published: July 2002

ABSTRACT

The
Fv1
gene restricts murine leukemia virus replication via an interaction with the viral capsid protein. To study this interaction, a number of mutations, including a series of N-terminal and C-terminal deletions, internal deletions, and a number of single-amino-acid substitutions, were introduced into the n and b alleles of the
Fv1
gene and the effects of these changes on virus restriction were measured. A significant fraction of the Fv1 protein was not required for restriction; however, retention of an intact major homology region as well as of domains toward the N and C termini was essential. Binding specificity appeared to be a combinatorial property of a number of residues within the C-terminal portion of Fv1.
Characterization of the Infectious Salmon Anemia Virus Genomic Segment That Encodes the Putative Hemagglutinin
Authors: Rimstad Espen , Mjaaland Siri , Snow Michael , Mikalsen Aase B. , Cunningham Carey O. 
Published: July 2002

ABSTRACT
The genomic segment encoding the putative hemagglutinin of infectious salmon anemia virus (ISAV) is described. Expression of the putative hemagglutinin in a salmon cell line demonstrated hemadsorptive properties of the protein for salmon erythrocytes. The polypeptide was recognized by an ISAV-specific monoclonal antibody. Nucleotide sequencing indicated the occurrence of a variable region in the hemagglutinin gene.
Epstein-Barr Virus Immediate-Early Protein BRLF1 Interacts with CBP, Promoting Enhanced BRLF1 Transactivation
Authors: Swenson Jennifer J. , Holley-Guthrie Elizabeth , Kenney Shannon C. 
Published: July 2002

ABSTRACT
The Epstein-Barr virus (EBV) immediate-early protein BRLF1 is a transcriptional activator that mediates the switch from latent to lytic viral replication. Many transcriptional activators function, in part, due to an interaction with histone acetylases, such as CREB-binding protein (CBP). Here we demonstrate that BRLF1 interacts with the amino and carboxy termini of CBP and that multiple domains of the BRLF1 protein are necessary for this interaction. Furthermore, we show that the interaction between BRLF1 and CBP is important for BRLF1-induced activation of the early lytic EBV gene SM in Raji cells.
Interleukin-1 Receptor Antagonist Gene Polymorphism and Circulating Levels of Human Immunodeficiency Virus Type 1 RNA in Brazilian Women
Authors: Witkin Steven S. , Linhares Iara M. , Gerber Stefan , Caetano Marie E. , Segurado Alusio C. 
Published: July 2002

ABSTRACTInterleukin-1 receptor antagonist (IL-1ra) gene polymorphisms in 83 human immunodeficiency virus (HIV)-seropositive women were evaluated. Fourteen of the subjects (16.9%) were homozygous for IL-1ra allele 2 (IL-1RN*2). These women had a lower median level of HIV RNA than did women homozygous for allele 1 (IL-1RN*1) (P= 0.01) or heterozygous for both alleles (P= 0.04). Among 46 subjects not receiving antiretroviral treatment, HIV levels were also reduced in IL-1RN*2 homozygous individuals (P< 0.05). There was no relation between IL-1ra alleles and CD4 levels.
HERV-K(OLD): Ancestor Sequences of the Human Endogenous Retrovirus Family HERV-K(HML-2)
Authors: Reus Katrin , Mayer Jens , Sauter Marlies , Zischler Hans , Müller-Lantzsch Nikolaus , Meese Eckart 
Published: July 2002

ABSTRACT

Sequences homologous to the human endogenous retrovirus (HERV) family HERV-K(HML-2) are present in all Old World primate species. A previous study showed that a central region of the HERV-K(HML-2)
gag
genes in
Hominoidea
species displays a 96-bp deletion compared to the
gag
genes in lower Old World primates. The more ancient HERV-K(HML-2) sequences present in lower Old World primates were apparently not conserved during hominoid evolution, as opposed to the deletion variants. To further clarify the evolutionary origin of the HERV-K(HML-2) family, we screened GenBank with the 96-bp
gag
-sequence characteristic of lower Old World primates and identified, to date, 10 human sequence entries harboring either full-length or partially deleted proviral structures, probably representing remnants of a more ancient HERV-K(HML-2) variant. The high degree of mutations demonstrates the long-time presence of these HERV-K(OLD) proviruses in the genome. Nevertheless, they still belong to the HML-2 family as deduced from dot matrix and phylogenetic analyses. We estimate, based on the family ages of integrated
Alu
elements and on long terminal repeat (LTR) divergence data, that the average age of HERV-K(OLD) proviruses is ca. 28 million years, supporting an integration time before the evolutionary split of
Hominoidea
from lower Old World primates. Analysis of HERV-K(OLD) LTR sequences led to the distinction of two subgroups, both of which cluster with LTRs belonging to an evolutionarily older cluster. Taken together, our data give further insight into the evolutionary history of the HERV-K(HML-2) family during primate evolution.
Characterization of the AdoMet-Dependent Guanylyltransferase Activity That Is Associated with the N Terminus of Bamboo Mosaic Virus Replicase
Authors: Li Yi-Ija , Chen Yi-Jun , Hsu Yau-Heiu , Meng Menghsiao 
Published: July 2002

ABSTRACT

Bamboo mosaic virus (BaMV), a member of the potexvirus group, infects primarily members of the
Bambusoideae
. Open reading frame 1 (ORF1) of BaMV encodes a 155-kDa polypeptide that has long been postulated to be a replicase involved in the replication and formation of the cap structure at the 5′ end of the viral genome. To identify and characterize the enzymatic activities associated with the N-terminal domain of the BaMV ORF1 protein, the intact replicase and two C-terminally truncated proteins were expressed in
Saccharomyces cerevisiae
. All three versions of BaMV ORF1 proteins could be radiolabeled by [α-
32
P]GTP, which is a characteristic of guanylyltransferase activity. The presence of
S
-adenosylmethionine (AdoMet) was essential for this enzymatic activity. Thin-layer chromatography analysis suggests that the radiolabeled moiety linked to the N-terminal domain of the BaMV ORF1 protein is m
7
GMP. The N-terminal domain also exhibited methyltransferase activity that catalyzes the transfer of the [
3
H]methyl group from AdoMet to GTP or guanylylimidodiphosphate. Therefore, during cap structure formation in BaMV, methylation of GTP may occur prior to transguanylation as for alphaviruses and brome mosaic virus. This study establishes the association of RNA capping activity with the N-terminal domain of the replicase of potexviruses and further supports the idea that the reaction sequence of RNA capping is conserved throughout the alphavirus-like superfamily of RNA viruses.
Strict Control of Human Immunodeficiency Virus Type 1 Replication by a Genetic Switch: Tet for Tat
Authors: Verhoef Koen , Marzio Giuseppe , Hillen Wolfgang , Bujard Hermann , Berkhout Ben 
Published: July 2002

ABSTRACT

Live-attenuated human immunodeficiency virus type 1 (HIV-1) variants have shown great promise as AIDS vaccines, but continued replication can lead to the selection of faster-replicating variants that are pathogenic. We therefore designed HIV-1 genomes that replicate exclusively upon addition of the nontoxic effector doxycycline (dox). This was achieved by replacement of the viral TAR-Tat system for transcriptional activation by the
Escherichia coli
-derived Tet system for inducible gene expression. These designer “HIV-rtTA” viruses replicate in a strictly dox-dependent manner both in a T-cell line and in primary blood cells, and the rate of replication can be fine-tuned by simple variation of the dox concentration. These HIV-rtTA viruses provide a tool to perform genetics, e.g., selection and optimization experiments, with the
E. coli
-derived Tet reagents in a eukaryotic background. Furthermore, such viruses may represent improved vaccine candidates because their replication can be turned on and off at will.
Inactivation of p21 by E1A Leads to the Induction of Apoptosis in DNA-Damaged Cells
Authors: Chattopadhyay Debasis , Ghosh Mrinal K. , Mal Asoke , Harter Marian L. 
Published: July 2002

ABSTRACT

A major impediment to successful chemotherapy is the propensity for some tumor cells to undergo cell cycle arrest rather than apoptosis. It is well established, however, that the adenovirus E1A protein can sensitize these cells to the induction of apoptosis by anticancer agents. To further understand how E1A enhances chemosensitivity, we have made use of a human colon carcinoma cell line (HCT116) which typically undergoes cell cycle arrest in response to chemotherapeutic drugs. As seen by the analysis of E1A mutants, we show here that E1A can induce apoptosis in these cells by neutralizing the activities of the cyclin-dependent kinase inhibitor p21. E1A's ability to interact with p21 and thereby restore Cdk2 activity in DNA-damaged cells correlates with the reversal of G
1
arrest, which in turn leads to apoptosis. Analysis of E1A mutants failing to bind p300 (also called CBP) or Rb shows that they are almost identical to wild-type E1A in their ability to initially overcome a G
1
arrest in cells after DNA damage, while an E1A mutant failing to bind p21 is not. However, over time, this mutant, which can still target Rb, is far more efficient in accumulating cells with a DNA content greater than 4
N
but is similar to wild-type E1A and the other E1A mutants in releasing cells from a p53-mediated G
2
block following chemotherapeutic treatment. Thus, we suggest that although E1A requires the binding of p21 to create an optimum environment for apoptosis to occur in DNA-damaged cells, E1A's involvement in other pathways may be contributing to this process as well. A model is proposed to explain the implications of these findings.
Mapping the Sequences That Mediate Interaction of the Equine Herpesvirus 1 Immediate-Early Protein and Human TFIIB
Authors: Jang Hyung K. , Albrecht Randy A. , Buczynski Kimberly A. , Kim Seong K. , Derbigny Wilbert A. , O'Callaghan Dennis J. 
Published: July 2002

ABSTRACT

The sole immediate-early (IE) gene of equine herpesvirus 1 encodes a 1,487-amino-acid (aa) regulatory phosphoprotein that independently activates expression of early viral genes. Coimmunoprecipitation assays demonstrated that the IE protein physically interacts with the general transcription factor TFIIB. Using a variety of protein-binding assays that employed a panel of IE truncation and deletion mutants expressed as in vitro-synthesized or glutathione
S
-transferase fusion proteins, we mapped a TFIIB-binding domain to aa 407 to 757 of the IE protein. IE mutants carrying internal deletions of aa 426 to 578 and 621 to 757 were partially defective for TFIIB binding, indicating that aa 407 to 757 may harbor more than one TFIIB-binding domain. The interaction between the IE protein and TFIIB is of physiological importance, as evidenced by transient-cotransfection assays. Partial deletion of the TFIIB-binding domain within the IE protein inhibited its ability to activate expression of the viral thymidine kinase gene, a representative early promoter, and of the IR5 gene, a representative late promoter, by greater than 20 and 50%, respectively. These results indicate that the interaction of the IE protein with TFIIB is necessary for its full transactivation function and that the IE-TFIIB interaction may be part of the mechanism by which the IE protein activates transcription.
Human Immunodeficiency Virus Type 1 Env Sequences from Calcutta in Eastern India: Identification of Features That Distinguish Subtype C Sequences in India from Other Subtype C Sequences
Authors: Shankarappa Raj , Chatterjee Ramdas , Learn Gerald H. , Neogi Dhruba , Ding Ming , Roy Pratima , Ghosh Adhir , Kingsley Lawrence , Harrison Lee , Mullins James I. , Gupta Phalguni 
Published: July 2002

ABSTRACT

India is experiencing a rapid spread of human immunodeficiency virus type 1 (HIV-1), primarily through heterosexual transmission of subtype C viruses. To delineate the molecular features of HIV-1 circulating in India, we sequenced the V3-V4 region of viral
env
from 21 individuals attending an HIV clinic in Calcutta, the most populous city in the eastern part of the country, and analyzed these and the other Indian sequences in the HIV database. Twenty individuals were infected with viruses having a subtype C
env
, and one had viruses with a subtype A
env
. Analyses of 192 subtype C sequences that included one sequence for each subject from this study and from the HIV database revealed that almost all sequences from India, along with a small number from other countries, form a phylogenetically distinct lineage within subtype C, which we designate C
IN
. Overall, C
IN
lineage sequences were more closely related to each other (level of diversity, 10.2%) than to subtype C sequences from Botswana, Burundi, South Africa, Tanzania, and Zimbabwe (range, 15.3 to 20.7%). Of the three positions identified as signature amino acid substitution sites for C
IN
sequences (K340E, K350A, and G429E), 56% of the C
IN
sequences contained all three amino acids while 87% of the sequences contained at least two of these substitutions. Among the non-C
IN
sequences, all three amino acids were present in 2%, while 22% contained two or more of these amino acids. These results suggest that much of the current Indian epidemic is descended from a single introduction into the country. Identification of conserved signature amino acid positions could assist epidemiologic tracking and has implications for the development of a vaccine against subtype C HIV-1 in India.
An Attenuating Mutation in the 2A Protease of Swine Vesicular Disease Virus, a Picornavirus, Regulates Cap- and Internal Ribosome Entry Site-Dependent Protein Synthesis
Authors: Sakoda Yoshihiro , Ross-Smith Natalie , Inoue Toru , Belsham Graham J. 
Published: July 2002

ABSTRACT
Virulent and avirulent strains of swine vesicular disease virus (SVDV), a picornavirus, have been characterized previously. The major determinants for attenuation have been mapped to specific residues in the 1D-2A-coding region. The properties of the 2A proteases from the virulent and avirulent strains of SVDV have now been examined. Both proteases efficiently cleaved the 1D/2A junction in vitro and in vivo. However, the 2A protease of the avirulent strain of SVDV was much less effective than the virulent-virus 2A protease at inducing cleavage of translation initiation factor eIF4GI within transfected cells. Hence the virulent-virus 2A protease is much more effective at inhibiting cap-dependent protein synthesis. Furthermore, the virulent-virus 2A protease strongly stimulated the internal ribosome entry sites (IRESs) from coxsackievirus B4 and from SVDV, while the avirulent-virus 2A protease was significantly less active in these assays. Thus, the different properties of the 2A proteases from the virulent and avirulent strains of SVDV in regulating protein synthesis initiation reflect the distinct pathogenic properties of the viruses from which they are derived. A single amino acid substitution, adjacent to His21 of the catalytic triad, is sufficient to confer the characteristics of the virulent-strain 2A protease on the avirulent-strain protease. It is concluded that the efficiency of picornavirus protein synthesis, controlled directly by the IRES or indirectly by the 2A protease, can determine virus virulence.
A Short N-Proximal Region in the Large Envelope Protein Harbors a Determinant That Contributes to the Species Specificity of Human Hepatitis B Virus
Authors: Chouteau P. , Le Seyec J. , Cannie I. , Nassal M. , Guguen-Guillouzo C. , Gripon P. 
Published: July 2002

ABSTRACT

Infection by hepatitis B virus (HBV) is mainly restricted to humans. This species specificity is likely determined at the early phase of the viral life cycle. Since the envelope proteins are the first viral factors to interact with the cell, they represent attractive candidates for controlling the HBV host range. To investigate this assumption, we took advantage of the recent discovery of a second virus belonging to the primate
Orthohepadnavirus
genus, the woolly monkey HBV (WMHBV). A recombinant plasmid was constructed for the expression of all WMHBV envelope proteins. In additional constructs, N-terminal sequences of the WMHBV large envelope protein were substituted for their homologous HBV counterparts. All wild-type and chimeric WMHBV surface proteins were properly synthesized by transfected human hepatoma cells, and they were competent to replace the original HBV proteins for the production of complete viral particles. The resulting pseudotyped virions were evaluated for their infectious capacity on human hepatocytes in primary culture. Virions pseudotyped with wild-type WMHBV envelope proteins showed a significant loss of infectivity. By contrast, infectivity was completely restored when the first 30 residues of the large protein originated from HBV. Analysis of smaller substitutions within this domain limited the most important region to a stretch of only nine amino acids. Reciprocally, replacement of this motif by WMHBV residues in the context of the HBV L protein significantly reduced infectivity of HBV. Hence this short region of the L protein contributes to the host range of HBV.
The Pattern of Tegument-Capsid Interaction in the Herpes Simplex Virus Type 1 Virion Is Not Influenced by the Small Hexon-Associated Protein VP26
Authors: Chen Dong-Hua , Jakana Joanita , McNab David , Mitchell Joyce , Zhou Z. Hong , Dougherty Matthew , Chiu Wah , Rixon Frazer J. 
Published: July 2002

ABSTRACT
Examination of the three-dimensional structure of intact herpes simplex virus type 1 (HSV-1) virions had revealed that the icosahedrally symmetrical interaction between the tegument and capsid involves the pentons but not the hexons (Z. H. Zhou, D. H. Chen, J. Jakana, F. J. Rixon, and W. Chiu, J. Virol. 73:3210–3218, 1999). To account for this, we postulated that the presence of the small capsid protein, VP26, on top of the hexons was masking potential binding sites and preventing tegument attachment. We have now tested this hypothesis by determining the structure of virions lacking VP26. Apart from the obvious absence of VP26 from the capsids, the structures of the VP26 minus and wild-type virions were essentially identical. Notably, they showed the same tegument attachment patterns, thereby demonstrating that VP26 is not responsible for the divergent tegument binding properties of pentons and hexons.