bluuebunny/crossref_metadata_2025_split huggingface dataset:
Virus Replication and Cytokine Production in Dengue Virus-Infected Human B Lymphocytes
Authors: Lin Yu-Wen , Wang Kuan-Ju , Lei Huan-Yao , Lin Yee-Shin , Yeh Trai-Ming , Liu Hsiao-Sheng , Liu Ching-Chuan , Chen Shun-Hua 
Published: November 2002

ABSTRACTDengue virus (DV) replication, antibody-enhanced viral infection, and cytokine responses of human primary B lymphocytes (cells) were characterized and compared with those of monocytes. The presence of a replication template (negative-strand RNA intermediate), viral antigens including core and nonstructural proteins, and increasing amounts of virus with time postinfection indicated that DV actively replicated in B cells. Virus infection also induced B cells to produce interleukin-6 and tumor necrosis factor alpha, which have been previously implicated in virus pathogenesis. In addition, a heterologous antibody was able to enhance both virus and cytokine production in B cells. Furthermore, the levels of virus replication, antibody-enhanced virus replication, and cytokine responses observed in B cells were not statistically different from those in monocytes. These results suggest that B cells may play an important role in DV pathogenesis.
An Antibody to the Putative Aphid Recognition Site on Cucumber Mosaic Virus Recognizes Pentons but Not Hexons
Authors: Bowman Valorie D. , Chase Elaine S. , Franz Alexander W. E. , Chipman Paul R. , Zhang Xing , Perry Keith L. , Baker Timothy S. , Smith Thomas J. 
Published: November 2002

ABSTRACT

Cucumber mosaic virus (CMV), the type member of the genus
Cucumovirus
(family
Bromoviridae
), is transmitted by aphids in a nonpersistent manner. Mutagenesis experiments identified the βH-βI loop of the capsid subunit as a potential key motif responsible for interactions with the insect vector. To further examine the functional characteristics of this motif, we generated monoclonal antibodies that bound to native virions but not to βH-βI mutants. Fab fragments from these antibodies were complexed with wild-type CMV and the virus-Fab structure was determined to 12-Å resolution by using electron cryomicroscopy and image reconstruction techniques. The electron density attributed to the bound antibody has a turret-like appearance and protrudes from each of the 12 fivefold axes of the icosahedral virus. Thus, the antibody binds only to the pentameric clusters (pentons) of A subunits of the T=3 quasisymmetric virus and does not appear to bind to any of the B and C subunits that occur as hexameric clusters (hexons) at the threefold (quasi-sixfold) axes. Modeling and electron density comparisons were used to analyze the paratope-epitope interface and demonstrated that the antibody binds to three βH-βI loops in three adjacent A subunits in each penton. This antibody can discriminate between A and B/C subunits even though the βH-βI loop adopts the same structure in all 180 capsid subunits and is therefore recognizing differences in subunit arrangements. Antibodies with such character have potential use as probes of viral assembly. Our results may provide an additional rationale for designing synthetic vaccines by using symmetrical viral particles.
Processing and Degradation of Exogenous Prion Protein by CD11c+Myeloid Dendritic Cells In Vitro
Authors: Luhr Katarina M. , Wallin Robert P. A. , Ljunggren Hans-Gustaf , Löw Peter , Taraboulos Albert , Kristensson Krister 
Published: November 2002

ABSTRACTThe immune system plays an important role in facilitating the spread of prion infections from the periphery to the central nervous system. CD11c+myeloid dendritic cells (DC) could, due to their subepithelial location and their migratory capacity, be early targets for prion infection and contribute to the spread of infection. In order to analyze mechanisms by which these cells may affect prion propagation, we studied in vitro the effect of exposing such DC to scrapie-infected GT1-1 cells, which produce the scrapie prion protein PrPSc. In this system, the DC efficiently engulfed the infected GT1-1 cells. Unexpectedly, PrPSc, which is generally resistant to protease digestion, was processed and rapidly degraded. Based on this observation we speculate that CD11c+DC may play a dual role in prion infections: on one hand they may facilitate neuroinvasion by transfer of the infectious agent as suggested from in vivo studies, but on the other hand they may protect against the infection by causing an efficient degradation of PrPSc. Thus, the migrating and highly proteolytic CD11c+myeloid DC may affect the balance between propagation and clearance of PrPScin the organism.
Saccharomyces cerevisiaeIs Permissive for Replication of Bovine Papillomavirus Type 1
Authors: Zhao Kong-Nan , Frazer Ian H. 
Published: November 2002

ABSTRACTWe recently demonstrated thatSaccharomyces cerevisiaeprotoplasts can take up bovine papillomavirus type 1 (BPV1) virions and that viral episomal DNA is replicated after uptake. Here we demonstrate that BPV virus-like particles are assembled in infectedS. cerevisiaecultures from newly synthesized capsid proteins and also package newly synthesized DNA, including full-length and truncated viral DNA andS. cerevisiae-derived DNA. Virus particles prepared inS. cerevisiaeare able to convey packaged DNA to Cos1 cells and to transform C127 cells. Infectivity was blocked by antisera to BPV1 L1 but not antisera to BPV1 E4. We conclude thatS. cerevisiaeis permissive for the replication of BPV1 virus.
Antibody Epitopes on the Neuraminidase of a Recent H3N2 Influenza Virus (A/Memphis/31/98)
Authors: Gulati Upma , Hwang Chi-Ching , Venkatramani Lalitha , Gulati Shelly , Stray Stephen J. , Lee Janis T. , Laver W. Graeme , Bochkarev Alexey , Zlotnick Adam , Air Gillian M. 
Published: November 2002

ABSTRACTWe have characterized monoclonal antibodies raised against the neuraminidase (NA) of a Sydney-like influenza virus (A/Memphis/31/98, H3N2) in a reassortant virus A/NWS/33HA-A/Mem/31/98NA(H1N2) and nine escape mutants selected by these monoclonal antibodies. Five of the antibodies use the same heavy chain VDJ genes and may not be independent. Another antibody, Mem5, uses the same VHand J genes with a different D gene and different isotype. Sequence changes in escape mutants selected by these antibodies occur in two loops of the NA, at amino acid 198, 199, 220, or 221. These amino acids are located on the opposite side of the NA monomer to the major epitopes found in N9 and early N2 NAs. Escape mutants with a change at 198 have reduced NA activity compared to the wild-type virus. Asp198 points toward the substrate binding pocket, and we had previously found that a site-directed mutation of this amino acid resulted in a loss of enzyme activity (M. R. Lentz, R. G. Webster, and G. M. Air, Biochemistry26:5351-5358, 1987). Mutations at residue 199, 220, or 221 did not alter the NA activity significantly compared to that of wild-type NA. A 3.5-Å structure of Mem5 Fab complexed with the Mem/98 NA shows that the Mem5 antibody binds at the sites of escape mutation selected by the other antibodies.
Identification of Six
Autographa californica
Multicapsid Nucleopolyhedrovirus Early Genes That Mediate Nuclear Localization of G-Actin
Authors: Ohkawa Taro , Rowe Annette R. , Volkman Loy E. 
Published: November 2002

ABSTRACT

Nuclear filamentous actin (F-actin) is required for nucleopolyhedrovirus (NPV) progeny production in NPV-infected, cultured lepidopteran cells. We have determined that monomeric G-actin is localized within the nuclei of host cells during the early stage of infection by
Autographa californica
multicapsid nucleopolyhedrovirus (Ac
M
NPV). With a library of cloned Ac
M
NPV genomic fragments, along with a plasmid engineered to express enhanced green fluorescent protein-
Bombyx mori
G-actin in transient transfection experiments, we identified six Ac
M
NPV early genes that mediate nuclear localization of G-actin in TN-368 cells:
ie-1
,
pe38
,
he65
,
Ac004, Ac102,
and
Ac152
. Within this subset,
ie-1
and
pe38
encode immediate-early transcriptional transactivators,
he65
encodes a delayed-early product, and the products encoded by
Ac004, Ac102,
and
Ac152
have not been characterized. We found that when driven by foreign promoters,
ie-1
,
pe38,
and
Ac004
had to be expressed prior to
Ac102
or
he65
for nuclear G-actin to accumulate and that expression of
Ac152
was no longer required. These results and others suggested that the product of
Ac152
was a transactivator (directly or indirectly) of both
Ac102
and
he65
and that recruitment of G-actin to the nucleus was a temporally regulated process. Determining the functions of each of the six Ac
M
NPV gene products with respect to our assay should provide valuable clues to basic cellular mechanisms of actin regulation and how Ac
M
NPV infection affects them.
Mutant Human Cytomegalovirus Lacking the Immediate-Early TRS1 Coding Region Exhibits a Late Defect
Authors: Blankenship Catherine A. , Shenk Thomas 
Published: November 2002

ABSTRACT

The human cytomegalovirus IRS1 and TRS1 open reading frames encode immediate-early proteins with identical N-terminal domains and divergent C-terminal regions. Both proteins have been shown previously to activate reporter genes in transfection assays in cooperation with other viral gene products. We have constructed two viruses carrying substitution mutations within either the IRS1 or TRS1 open reading frame. AD
sub
IRS1 failed to produce the related IRS1 and IRS1
263
proteins, but it replicated with normal kinetics to produce a wild-type yield in human fibroblasts. The addition in
trans
of the IRS1
263
protein, which antagonizes the ability of IRS1 and TRS1 proteins to activate reporter genes, did not inhibit the growth of the mutant virus. AD
sub
TRS1 failed to produce the TRS1 protein, and it generated an ∼200-fold-reduced yield of infectious virus in comparison to its wild-type parent. Viral DNA accumulated normally, as did a set of viral mRNAs that were monitored in AD
sub
TRS1-infected cells. However, two tegument proteins were partially mislocalized and infectious virus particles did not accumulate to normal levels within AD
sub
TRS1-infected cells. Further, infectious AD
sub
TRS1 particles sedimented abnormally in a glycerol-tartrate gradient, indicating that the structure of the mutant particles is aberrant. Our analysis of the AD
sub
TRS1 phenotype indicates that the TRS1 protein is required, either directly or indirectly, for efficient assembly of virus particles.
The Membrane-Proximal Domain of Vesicular Stomatitis Virus G Protein Functions as a Membrane Fusion Potentiator and Can Induce Hemifusion
Authors: Jeetendra E. , Robison Clinton S. , Albritton Lorraine M. , Whitt Michael A. 
Published: November 2002

ABSTRACT

Recently we showed that the membrane-proximal stem region of the vesicular stomatitis virus (VSV) G protein ectodomain (G stem [GS]), together with the transmembrane and cytoplasmic domains, was sufficient to mediate efficient VSV budding (C. S. Robison and M. A. Whitt, J. Virol. 74:2239-2246, 2000). Here, we show that GS can also potentiate the membrane fusion activity of heterologous viral fusion proteins when GS is coexpressed with those proteins. For some fusion proteins, there was as much as a 40-fold increase in syncytium formation when GS was coexpressed compared to that seen when the fusion protein was expressed alone. Fusion potentiation by GS was not protein specific, since it occurred with both pH-dependent as well as pH-independent fusion proteins. Using a recombinant vesicular stomatitis virus encoding GS that contained an N-terminal hemagglutinin (HA) tag (GS
HA
virus), we found that the GS
HA
virus bound to cells as well as the wild-type virus did at pH 7.0; however, the GS
HA
virus was noninfectious. Analysis of cells expressing GS
HA
in a three-color membrane fusion assay revealed that GS
HA
could induce lipid mixing but not cytoplasmic mixing, indicating that GS can induce hemifusion. Treatment of GS
HA
virus-bound cells with the membrane-destabilizing drug chlorpromazine rescued the hemifusion block and allowed entry and subsequent replication of GS
HA
virus, demonstrating that GS-mediated hemifusion was a functional intermediate in the membrane fusion pathway. Using a series of truncation mutants, we also determined that only 14 residues of GS, together with the VSV G transmembrane and cytoplasmic tail, were sufficient for fusion potentiation. To our knowledge, this is the first report which shows that a small domain of one viral glycoprotein can promote the fusion activity of other, unrelated viral glycoproteins.
The p23 Protein of Hibiscus Chlorotic Ringspot Virus Is Indispensable for Host-Specific Replication
Authors: Liang Xiao-Zhen , Lucy Andrew P. , Ding Shou-Wei , Wong Sek-Man 
Published: November 2002

ABSTRACT

Hibiscus chlorotic ringspot virus (HCRSV) possesses a novel open reading frame (ORF) which encodes a putative 23-kDa protein (p23). We report here the in vivo detection of p23 and demonstrate its essential role in viral replication. The expression of p23 could be detected in protein extracts from transfected kenaf (
Hibiscus cannabinus
L.) protoplasts and in HCRSV-infected leaves. Further, direct immunoblotting of infected kenaf leaves also showed the presence of p23, and transient expression in onion and kenaf cells demonstrated that the protein is distributed throughout the cell. Site-directed mutagenesis showed that mutations introduced into the ORF of p23 abolished viral replication in kenaf protoplasts and plants but not in
Chenopodium quinoa
L. The loss of function of the p23 mutant M23/S33-1 could be complemented in
trans
upon the induced expression of p23 from an infiltrated construct bearing the ORF (pCam23). Altogether, these results demonstrate that p23 is a bona fide HCRSV protein that is expressed in vivo and suggest that p23 is indispensable for the host-specific replication of HCRSV. In addition, we show that p23 does not bind nucleic acids in vitro and does not act as a suppressor of posttranscriptional gene silencing in transgenic tobacco carrying a green fluorescent protein.
Generation of Hepatitis C Virus-Like Particles by Use of a Recombinant Vesicular Stomatitis Virus Vector
Authors: Ezelle Heather J. , Markovic Dubravka , Barber Glen N. 
Published: November 2002

ABSTRACT
Hepatitis C virus (HCV), a major etiologic agent of hepatocellular carcinoma, presently infects approximately 400 million people worldwide, making the development of protective measures against HCV infection a key objective. Here we have generated a recombinant vesicular stomatitis virus (VSV), which expresses the HCV structural proteins, by inserting the contiguous Core, E1, and E2 coding region of HCV into the VSV genome. Recombinant VSV expressing HCV Core, E1, and E2 (VSV-HCV-C/E1/E2) grew to high titers in vitro and efficiently expressed the incorporated HCV gene product, which became fully processed into the individual HCV structural proteins. Biochemical and biophysical analysis indicated that the HCV Core, E1, and E2 proteins assembled to form HCV-like particles (HCV-LPs) possessing properties similar to the ultrastructural properties of HCV virions. Mice immunized with VSV-HCV-C/E1/E2 generated cell-mediated immune responses to all of the HCV structural proteins, and humoral responses, particularly to E2, were also readily evident. Our data collectively indicate that engineered VSVs expressing HCV Core, E1, and E2 and/or HCV-LPs represent useful tools in vaccine and immunotherapeutic strategies designed to address HCV infection.
Binding of Norwalk Virus-Like Particles to ABH Histo-Blood Group Antigens Is Blocked by Antisera from Infected Human Volunteers or Experimentally Vaccinated Mice
Authors: Harrington Patrick R. , Lindesmith Lisa , Yount Boyd , Moe Christine L. , Baric Ralph S. 
Published: November 2002

ABSTRACT

Attachment of Norwalk (NV), Snow Mountain (SMV), and Hawaii (HV) virus-like particles (VLPs) to specific ABH histo-blood group antigens was investigated by using human saliva and synthetic biotinylated carbohydrates. The three distinct Norwalk-like viruses (NLVs) have various capacities for binding ABH histo-blood group antigens, suggesting that different mechanisms for NLV attachment likely exist. Importantly, antisera from NV-infected human volunteers, as well as from mice inoculated with packaged Venezuelan equine encephalitis virus replicons expressing NV VLPs, blocked the ability of NV VLPs to bind synthetic H type 1, Le
b
, and H type 3, suggesting a potential mechanism for antibody-mediated neutralization of NV.
Viral Evolution during Structured Treatment Interruptions in Chronically Human Immunodeficiency Virus-Infected Individuals
Authors: Martinez-Picado Javier , Frost Simon D. W. , Izquierdo Nuria , Morales-Lopetegi K. , Marfil Silvia , Puig Teresa , Cabrera Cecilia , Clotet Bonaventura , Ruiz Lidia 
Published: November 2002

ABSTRACT

We analyzed the evolution of the human immunodeficiency virus type 1 (HIV-1)
env
gene in 12 chronically infected individuals who underwent structured treatment interruptions (STIs). Analyses of length variation and of clonal sequences demonstrated highly unpredictable evolution, which may limit the strengthening of HIV-specific immune responses by STIs because of the variability in exposure to viral antigens.
Targeted Derepression of the Human Immunodeficiency Virus Type 1 Long Terminal Repeat by Pyrrole-Imidazole Polyamides
Authors: Coull Jason J. , He Guocheng , Melander Christian , Rucker Victor C. , Dervan Peter B. , Margolis David M. 
Published: November 2002

ABSTRACT
The host factor LSF represses the human immunodeficiency virus type 1 long terminal repeat (LTR) by mediating recruitment of histone deacetylase. We show that pyrrole-imidazole polyamides targeted to the LTR can specifically block LSF binding both in vitro and within cells via direct access to chromatin, resulting in increased LTR expression.
Mucosal Immunization with Live Recombinant Bovine Respiratory Syncytial Virus (BRSV) and Recombinant BRSV Lacking the Envelope Glycoprotein G Protects against Challenge with Wild-Type BRSV
Authors: Schmidt Ulrike , Beyer Jörg , Polster Ulf , Gershwin Laurel J. , Buchholz Ursula J. 
Published: November 2002

ABSTRACTRecombinant bovine respiratory syncytial virus (rBRSV) and an rBRSV deletion mutant lacking the G gene (rBRSVΔG) were characterized in calves with respect to replication competence, attenuation, and protective efficacy as live-attenuated BRSV vaccines. Both recombinant viruses were safe and induced protection against a BRSV challenge infection. rBRSV replicated efficiently in the upper respiratory tract. Intranasal immunization with rBRSVΔG led to infection but not to mucosal virus replication. Neutralizing antibodies were induced by rBRSV and rBRSVΔG. Thus, the BRSV attachment glycoprotein G seems to be dispensable in vaccinating calves against BRSV.
Comparison of Abnormal Prion Protein Glycoform Patterns from Transmissible Spongiform Encephalopathy Agent-Infected Deer, Elk, Sheep, and Cattle
Authors: Race Richard E. , Raines Anne , Baron Thierry G. M. , Miller Michael W. , Jenny Allen , Williams Elizabeth S. 
Published: November 2002

ABSTRACT
Analysis of abnormal prion protein glycoform patterns from chronic wasting disease (CWD)-affected deer and elk, scrapie-affected sheep and cattle, and cattle with bovine spongiform encephalopathy failed to identify patterns capable of reliably distinguishing these transmissible spongiform encephalopathy diseases. However, PrP-res patterns sometimes differed among individual animals, suggesting infection by different or multiple CWD strains in some species.
Host Range and Receptor Binding Properties of Vectors Bearing Feline Leukemia Virus Subgroup B Envelopes Can Be Modulated by Envelope Sequences outside of the Receptor Binding Domain
Authors: Faix Peggy Ho , Feldman Steven A. , Overbaugh Julie , Eiden Maribeth V. 
Published: November 2002

ABSTRACT
To evaluate host range differences between two different strains of feline leukemia virus subgroup B (FeLV-B), we compared the binding and infectivity patterns of retrovirus vectors bearing either FeLV-B-90Z or FeLV-B-GA envelopes. We report here that the ability of these envelopes to utilize different Pit1 orthologs is mediated primarily by the receptor binding domain; however, in the case of FeLV-B-90Z, the C terminus also contributes to the recognition of certain Pit1 orthologs.
Regulatory Mechanisms by Which Barrier-to-Autointegration Factor Blocks Autointegration and Stimulates Intermolecular Integration of Moloney Murine Leukemia Virus Preintegration Complexes
Authors: Suzuki Youichi , Craigie Robert 
Published: November 2002

ABSTRACT
Retroviral integration is mediated by a preintegration complex (PIC) which contains the viral DNA made by reverse transcription together with associated protein factors. Prior to association with target DNA, the PIC must avoid suicidal intramolecular integration of its viral DNA (autointegration). We have demonstrated that barrier-to-autointegration factor (BAF) blocks the autointegration of Moloney murine leukemia virus (MoMLV) PICs in vitro. In this study, we show that BAF is an authentic component of MoMLV. Analysis of the sedimentation properties of initial, salt-stripped, and BAF-reconstituted PICs reveals that the viral DNA within the PIC is reversibly compacted by BAF, consistent with the functional role of BAF in protecting the viral DNA from autointegration. Furthermore, we find that BAF can promote the association of PICs with target DNA. Thus, our data suggest that BAF plays critical roles in promoting preferential intermolecular integration by both blocking autointegration and stimulating the capture of target DNA.
RNA Structure and Packaging Signals in the 5′ Leader Region of the Human Immunodeficiency Virus Type 1 Genome
Authors: Clever Jared L. , Miranda, Daniel , Parslow Tristram G. 
Published: November 2002

ABSTRACT
The leader region of the human immunodeficiency virus type 1 (HIV-1) genome has a highly folded structure, comprising at least two RNA stem-loops [the transactivation response (TAR) and poly(A) hairpins] near its 5′ end and four others (SL1 to SL4) downstream. Each of these stem-loops contributes to the function of the HIV-1 packaging signal, which efficiently targets genomic RNA into nascent virions. The central 140-base region of the leader, which includes the U5 and primer binding site (PBS) sequences, is also believed to adopt a complex structure, but the nature of this structure and its possible role in RNA packaging have not been extensively explored. Here we report a mutational analysis identifying at least three separate loci within the U5-PBS region which, when mutated, impair both HIV-1 packaging specificity and infectivity in a single-round proviral assay. In common with those of all previously described packaging signals in the leader, the function of one of these loci appeared to depend on secondary structure rather than on sequence alone. By contrast, the activity of the other two loci did not correlate with any predicted conformations. Moreover, unlike SL1 to SL4, the TAR, poly(A), and U5-PBS hairpins were not bound with high affinity by the nucleocapsid portion of the HIV-1 Gag protein in vitro, implying that they contribute to packaging through a mechanism distinct from that of SL1 to SL4. Our findings confirm the existence and importance of secondary structure around the PBS and demonstrate that functional packaging signals are distributed across the entire HIV-1 leader.