bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functional Expression of Chemokine Receptor CCR5 on CD4+T Cells during Virus-Induced Central Nervous System Disease
Authors: Glass William G. , Lane Thomas E. 
Published: December 2002

ABSTRACTIntracranial infection of C57BL/6 mice with mouse hepatitis virus (MHV) results in an acute encephalomyelitis followed by a demyelinating disease similar in pathology to the human disease multiple sclerosis (MS). CD4+T cells are important in amplifying demyelination by attracting macrophages into the central nervous system (CNS) following viral infection; however, the mechanisms governing the entry of these cells into the CNS are poorly understood. The role of chemokine receptor CCR5 in trafficking of virus-specific CD4+T cells into the CNS of MHV-infected mice was investigated. CD4+T cells from immunized CCR5+/+and CCR5−/−mice were expanded in the presence of the immunodominant epitope present in the MHV transmembrane (M) protein encompassing amino acids 133 to 147 (M133-147). Adoptive transfer of CCR5+/+-derived CD4+T cells to MHV-infected RAG1−/−mice resulted in CD4+-T-cell entry into the CNS and clearance of virus from the brain. These mice also displayed robust demyelination correlating with macrophage accumulation within the CNS. Conversely, CD4+T cells from CCR5−/−mice displayed an impaired ability to traffic into the CNS of MHV-infected RAG1−/−recipients, which correlated with increased viral titers, diminished macrophage accumulation, and limited demyelination. Analysis of chemokine receptor mRNA expression by M133-147-expanded CCR5−/−-derived CD4+T cells revealed reduced expression of CCR1, CCR2, and CXCR3, indicating that CCR5 signaling is important in increased expression of these receptors, which aid in trafficking of CD4+T cells into the CNS. Collectively these results demonstrate that CCR5 signaling is important to migration of CD4+T cells to the CNS following MHV infection.
Role of Microglial Cells in Selective Replication of Simian Immunodeficiency Virus Genotypes in the Brain
Authors: Babas Tahar , Muñoz Daniel , Mankowski Joseph L. , Tarwater Patrick M. , Clements Janice E. , Zink M. Christine 
Published: December 2002

ABSTRACT

An accelerated, consistent macaque simian immunodeficiency virus (SIV) model in which over 90% of pigtailed macaques (
Macaca nemestrina
) coinoculated with SIV/17E-Fr and SIV/DeltaB670 developed encephalitis was used to determine whether central nervous system (CNS) lesions are associated with the replication of specific genotypes in the brain and, more specifically, in the microglia. Ten of 11 inoculated macaques had severe (
n
= 3), moderate (
n
= 5), or mild (
n
= 2) encephalitis at 3 months postinoculation. To compare actively replicating viral genotypes in the CNS and in microglia with those in the periphery, the V1 region of the SIV envelope gene was amplified and sequenced from RNA extracted from basal ganglia, from microglial cells isolated from the brain, and from peripheral blood mononuclear cells (PBMC) isolated from blood at the time of death. To distinguish between actively replicating with latent viral genotypes in the CNS, viral genotypes in RNA and DNA from basal ganglia were compared. Two macrophage-tropic, neurovirulent viruses, SIV/17E-Fr and SIV/DeltaB670 Cl-2, predominated in the brain RNA of macaques with encephalitis, comprising 95% of the genotypes detected. The same two viral genotypes were present at the same frequencies in microglial cell RNA, suggesting that microglia are pivotal in the selective replication of neurovirulent viruses. There was a significantly greater number of viral genotypes in DNA than there were in RNA in the brain (
P
= 0.004), including those of both the macrophage- and lymphocyte-tropic viral strains. Furthermore, significantly fewer viral genotypes were detected in brain RNA than in PBMC RNA at the time of death (
P
= 0.004) and the viral strain that predominated in the brain frequently was different from that which predominated in the PBMC of the same animal. These data suggest that many viral genotypes enter the brain, but only a limited subset of macrophage-tropic, neurovirulent viruses replicate terminally in the brains of macaques with encephalitis. They further suggest that the selection of macrophage-tropic, neurovirulent viruses occurs not at the level of the blood-brain barrier but at a stage after virus entry and that microglial cells may play an important role in that selection process.
Novel Member of the
CD209
(
DC-SIGN
) Gene Family in Primates
Authors: Bashirova Arman A. , Wu Li , Cheng Jie , Martin Thomas D. , Martin Maureen P. , Benveniste Raoul E. , Lifson Jeffrey D. , KewalRamani Vineet N. , Hughes Austin , Carrington Mary 
Published: December 2002

ABSTRACT

Two
CD209
family genes identified in humans,
CD209
(
DC-SIGN
) and
CD209L
(
DC-SIGNR
/
L-SIGN
), encode C-type lectins that serve as adhesion receptors for ICAM-2 and ICAM-3 and participate in the transmission of human and simian immunodeficiency viruses (HIV and SIV, respectively) to target cells in vitro. Here we characterize the
CD209
gene family in nonhuman primates and show that recent evolutionary alterations have occurred in this family across primate species. All of the primate species tested, specifically, Old World monkeys (OWM) and apes, have orthologues of human
CD209
. In contrast,
CD209L
is missing in OWM but present in apes. A third family member, that we have named
CD209L2
, was cloned from rhesus monkey cDNA and subsequently identified in OWM and apes but not in humans. Rhesus
CD209L2
mRNA was prominently expressed in the liver and axillary lymph nodes, although preliminary data suggest that levels of expression may vary among individuals. Despite a high level of sequence similarity to both human and rhesus CD209, rhesus CD209L2 was substantially less effective at binding ICAM-3 and poorly transmitted HIV type 1 and SIV to target cells relative to CD209. Our data suggest that the
CD209
gene family has undergone recent evolutionary processes involving duplications and deletions, the latter of which may be tolerated because of potentially redundant functional activities of the molecules encoded by these genes.
Identification of a Lytic-Cycle Epstein-Barr Virus Gene Product That Can Regulate PKR Activation
Authors: Poppers Jeremy , Mulvey Matthew , Perez Cesar , Khoo David , Mohr Ian 
Published: December 2002

ABSTRACT
The Epstein-Barr virus (EBV) SM protein is a posttranscriptional regulator of viral gene expression. Like many transactivators encoded by herpesviruses, SM transports predominantly unspliced viral mRNA cargo from the nucleus to the cytosol, where it is subsequently translated. This activity likely involves a region of the protein that has homology to the herpes simplex virus type 1 (HSV-1) ICP27 gene product, the first member of this class of regulators to be discovered. However, SM also contains a repetitive segment rich in arginine and proline residues that is dispensable for its effects on RNA transport and splicing. This portion of SM, comprised of RXP triplet repeats, shows homology to the carboxyl-terminal domain of Us11, a double-stranded RNA (dsRNA) binding protein encoded by HSV-1 that inhibits activation of the cellular PKR kinase. To evaluate the intrinsic ability of SM to regulate PKR, we expressed and purified several SM protein derivatives and examined their activity in a variety of biochemical assays. The full-length SM protein bound dsRNA, associated physically with PKR, and prevented PKR activation. Removal of the 37-residue RXP domain significantly compromised all of these activities. Furthermore, the SM RXP domain was itself sufficient to inhibit PKR activation and interact with the kinase. Relative to its Us11 counterpart, the SM RXP segment bound dsRNA with reduced affinity and responded differently to single-stranded competitor polynucleotides. Thus, SM represents the first EBV gene product expressed during the lytic cycle that can prevent PKR activation. In addition, the RXP repeat segment appears to be a conserved herpesvirus motif capable of associating with dsRNA and modulating activation of the PKR kinase, a molecule important for the control of translation and the cellular antiviral response.
Characterization of a Siberian Virus Isolated from a Patient with Progressive Chronic Tick-Borne Encephalitis
Authors: Gritsun T. S. , Frolova T. V. , Zhankov A. I. , Armesto M. , Turner S. L. , Frolova M. P. , Pogodina V. V. , Lashkevich V. A. , Gould E. A. 
Published: December 2002

ABSTRACTA strain ofTick-borne encephalitis virusdesignated Zausaev (Za) was isolated in Siberia from a patient who died of a progressive (2-year) form of tick-borne encephalitis 10 years after being bitten by a tick. The complete genomic sequence of this virus was determined, and an attempt was made to correlate the sequence with the biological characteristics of the virus. Phylogenetic analysis demonstrated that this virus belongs to the Siberian subtype ofTick-borne encephalitis virus. Comparison of Za virus with two related viruses, a Far Eastern isolate, Sofjin, and a Siberian isolate, Vasilchenko, revealed differences among the three viruses in pathogenicity for Syrian hamsters, cytopathogenicity for PS cells, plaque morphology, and the electrophoretic profiles of virus-specific nonstructural proteins. Comparative amino acid alignments revealed 10 individual amino acid substitutions in the Za virus polyprotein sequence that were different from those of other tick-borne flaviviruses. Notably, the dimeric form of the Za virus NS1 protein migrated in polyacrylamide gels as a heterogeneous group of molecules with a significantly higher electrophoretic mobility than those of the Sofjin and Vasilchenko viruses. Two amino acid substitutions, T277→V and E279→G, within the NS1 dimerization domain are probably responsible for the altered oligomerization of Za virus NS1. These studies suggest that the patient from whom Za virus was isolated died due to increased pathogenicity of the latent virus following spontaneous mutagenesis.
The Genome Length of Human Parainfluenza Virus Type 2 Follows the Rule of Six, and Recombinant Viruses Recovered from Non-Polyhexameric-Length Antigenomic cDNAs Contain a Biased Distribution of Correcting Mutations
Authors: Skiadopoulos Mario H. , Vogel Leatrice , Riggs Jeffrey M. , Surman Sonja R. , Collins Peter L. , Murphy Brian R. 
Published: December 2002

ABSTRACT

Members of the
Paramyxovirinae
subfamily of the
Paramyxoviridae
family of viruses have the unusual requirement that the nucleotide length of the viral genome must be an even multiple of six in order for efficient RNA replication, and hence virus replication, to occur. Human parainfluenza virus type 2 (HPIV2) is the only member of the genus that has been reported to have a genome length that is not an even multiple of six, and it has also been recovered from a full-length antigenomic-sense cDNA that did not conform to the “rule of six.” To reexamine the issue of nucleotide length in natural isolates of HPIV2, a complete consensus genomic sequence was determined for three HPIV2 strains: Greer, Vanderbilt/1994 (V94), and Vanderbilt/1998. Each of these strains was found to have a genome length of 15,654 nucleotides (nt), thus conforming in each case to the rule of six. To directly examine the requirement that the genomic length of HPIV2 be an even multiple of six, we constructed six full-length antigenomic HPIV2/V94 cDNAs that deviated from a polyhexameric length by 0 to 5 nt. Recombinant HPIV2s were readily recovered from all of the cDNAs, including those that did not conform to the rule of six. One recombinant HPIV2 isolate was completely sequenced for each of the nonpolyhexameric antigenomic cDNAs. These were found to contain small nucleotide insertions or deletions that conferred polyhexameric length to the recovered genome. Interestingly, almost all of the length corrections occurred within the hemagglutinin-neuraminidase and large polymerase genes or the intervening intergenic region and thus were proximal to the insert that caused the deviation from the rule of six. These results demonstrate, in the context of complete infectious virus, that HPIV2 has a strong and seemingly absolute requirement for a polyhexameric genome.
Early Synthesis of Budded Virus Envelope Fusion Protein GP64 Enhances
Autographa californica
Multicapsid Nucleopolyhedrovirus Virulence in Orally Infected
Heliothis virescens
Authors: Washburn Jan O. , Chan Eric Y. , Volkman Loy E. , Aumiller Jared J. , Jarvis Donald L. 
Published: December 2002

ABSTRACT

Autographa californica
multicapsid nucleopolyhedrovirus (Ac
M
NPV), the type species of the
Nucleopolyhedrovirus
genus (
Baculoviridae
family), has two highly unusual traits shared by several baculovirus species. First, the occlusion-derived virus (ODV) that establishes primary infection in the midgut following its ingestion by host larvae contains multiple nucleocapsids, all of which enter the same midgut cell. Second, GP64, the envelope fusion protein of the budded virus (BV) that spreads infection beyond the midgut, is synthesized both early and late during infection. We tested the hypothesis that, together, these two traits enable parental ODV nucleocapsids to bud from infected midgut cells, essentially as BV, to establish secondary infections prior to completion of viral replication within the midgut. This “pass-through” strategy would enable the virus to counter the host's principal defense, sloughing of infected midgut cells, by accelerating the onset of systemic infections. To test this hypothesis, we created an Ac
M
NPV recombinant, AcLate21/20-64HB, that can express
gp64
only during the late phase of infection (coincident with the other structural proteins). We then compared the virulence of this virus to that of a control recombinant virus that expresses
gp64
in a wild-type manner. We found that when administered orally, the control virus was far more virulent and established secondary infection earlier than AcLate21/20-64HB, but when administered intrahemocoelically, infectivity and virulence of the two recombinants were identical. Our results demonstrate that early
gp64
expression is a key component of a unique and highly adaptive baculovirus infection strategy.
Ontogeny and Specificities of Mucosal and Blood Human Immunodeficiency Virus Type 1-Specific CD8+Cytotoxic T Lymphocytes
Authors: Musey L. , Ding Y. , Cao J. , Lee J. , Galloway C. , Yuen A. , Jerome K. R. , McElrath M. J. 
Published: December 2002

ABSTRACTInduction of adaptive immunity to human immunodeficiency virus type 1 (HIV-1) at the mucosal site of transmission is poorly understood but crucial in devising strategies to control and prevent infection. To gain further understanding of HIV-1-specific T-cell mucosal immunity, we established HIV-1-specific CD8+cytotoxic T-lymphocyte (CTL) cell lines and clones from the blood, cervix, rectum, and semen of 12 HIV-1-infected individuals and compared their specificities, cytolytic function, and T-cell receptor (TCR) clonotypes. Blood and mucosal CD8+CTL had common HIV-1 epitope specificities and major histocompatibility complex restriction patterns. Moreover, both systemic and mucosal CTL lysed targets with similar efficiency, primarily through the perforin-dependent pathway in in vitro studies. Sequence analysis of the TCRβ VDJ region revealed in some cases identical HIV-1-specific CTL clones in different compartments in the same HIV-1-infected individual. These results clearly establish that a subset of blood and mucosal HIV-1-specific CTL can have a common origin and can traffic between anatomically distinct compartments. Thus, these effectors can provide immune surveillance at the mucosa, where rapid responses are needed to contain HIV-1 infection.
Effective Inhibition of Kb- and Db-Restricted Antigen Presentation in Primary Macrophages by Murine Cytomegalovirus
Authors: LoPiccolo Diane M. , Gold Marielle C. , Kavanagh Daniel G. , Wagner Markus , Koszinowski Ulrich H. , Hill Ann B. 
Published: December 2002

ABSTRACTMacrophages play an important role in murine cytomegalovirus (MCMV) infection in vivo, both in disseminating infection and in harboring latent virus. MCMV encodes three immune evasion genes (m4,m6, andm152) that interfere with the ability of cytotoxic T cells (CTL) to detect virus-infected fibroblasts, but the efficacy of immune evasion in macrophages has been controversial. Here we show that MCMV immune evasion genes function in H-2bprimary bone marrow macrophages (BMMφ) in the same way that they do in fibroblasts. Metabolic labeling experiments showed that class I is retained in the endoplasmic reticulum by MCMV infection and associates with m4/gp34 to a similar extent in fibroblasts and BMMφ. We tested a series of Kb- and Db-restricted CTL clones specific for MCMV early genes against a panel of MCMV wild-type virus and mutants lackingm152,m4, orm6. MCMV immune evasion genes effectively inhibited antigen presentation.m152appeared sufficient to abolish Db-restricted presentation in infected macrophages, as has been previously observed in infected fibroblasts. However, for inhibition of recognition of infected macrophages by Kb-restricted CTL,m4,m6, andm152were all required. The contribution ofm4to inhibition of recognition appeared much more important in macrophages than in fibroblasts. Thus, MCMV immune evasion genes function effectively in primary macrophages to prevent CTL recognition of early antigens and show the same pattern of major histocompatibility complex class I allele discrimination as is seen in fibroblasts. Furthermore, for inhibition of Kb-restricted presentation, a strong synergistic effect was noted amongm152,m4, andm6.
Isolation and Molecular Characterization of a Nelfinavir (NFV)-Resistant Human Immunodeficiency Virus Type 1 That Exhibits NFV-Dependent Enhancement of Replication
Authors: Matsuoka-Aizawa Saori , Sato Hironori , Hachiya Atsuko , Tsuchiya Kiyoto , Takebe Yutaka , Gatanaga Hiroyuki , Kimura Satoshi , Oka Shinichi 
Published: December 2002

ABSTRACT

During the use of a phenotypic anti-human immunodeficiency virus type 1 (HIV-1) drug resistance assay in a large set of clinical virus isolates, we found a unique variant (CL-4) that exhibited a high level of nelfinavir (NFV) resistance and rather enhanced replication under subinhibitory concentrations of NFV (0.001 to 0.1 μM). Comparison of
gag-pol
sequences of the CL-4 variant and its predecessor virus isolates showed a stepwise accumulation of a total of 19 amino acid substitutions in protease (PR) and Gag p17 during 32-month NFV-containing antiretroviral therapy, while other Gag regions including the cleavage sites of the p55 precursor remained highly conserved. To understand the relationship between the genetic and phenotypic changes in CL-4, we constructed chimeric viruses using pNL4-3, replacing the PR, p24PR, or p17PR gene segment of CL-4 or its predecessor. A series of tissue culture infections with the chimeras in the absence or presence of increasing concentrations of NFV demonstrated that only the p17PR segment of CL-4 could confer the NFV-dependent replication enhancement phenotype on NL4-3. Our data suggest a novel adaptation mechanism of HIV-1 to NFV, in which coevolution of Gag and PR genes generates a variant that replicates more efficiently in the cellular environment in the presence of NFV than without the drug.
Ac23, an Envelope Fusion Protein Homolog in the Baculovirus
Autographa californica
Multicapsid Nucleopolyhedrovirus, Is a Viral Pathogenicity Factor
Authors: Lung Oliver Y. , Cruz-Alvarez Marilyn , Blissard Gary W. 
Published: December 2002

ABSTRACT

Viral envelope fusion proteins are important structural proteins that mediate viral entry and may affect or determine the host range of a virus. The acquisition, exchange, and evolution of such envelope proteins may dramatically affect the success and evolutionary divergence of viruses. In the family
Baculoviridae,
two very different envelope fusion proteins have been identified. Budded virions of group I nucleopolyhedroviruses (NPVs) such as the
Autographa californica
multicapsid nucleopolyhedrovirus (Ac
M
NPV), contain the essential GP64 envelope fusion protein. In contrast group II NPVs and granuloviruses have no
gp64
gene but instead encode a different envelope protein called F. F proteins from group II NPVs can functionally substitute for GP64 in
gp64
null Ac
M
NPV viruses, indicating that GP64 and these F proteins serve a similar functional role. Interestingly, Ac
M
NPV (and other
gp64
-containing group I NPVs) also contain an
F
gene homolog (
Ac23
) but the Ac
M
NPV F homolog cannot compensate for the loss of
gp64
. In the present study, we show that Ac23 is expressed and is found in budded virions. To examine the function of F protein homologs from the
gp64
-containing baculoviruses, we generated an
Ac23
null Ac
M
NPV genome by homologous recombination in
E. coli.
We found that
Ac23
was not required for viral replication or pathogenesis in cell culture or infected animals. However,
Ac23
accelerated the mortality of infected insect hosts by approximately 28% or 26 h. Thus, Ac23 represents an important viral pathogenicity factor in larvae infected with Ac
M
NPV.
Transcription Strategy in a
Closterovirus:
a Novel 5′-Proximal Controller Element of
Citrus Tristeza Virus
Produces 5′- and 3′-Terminal Subgenomic RNAs and Differs from 3′ Open Reading Frame Controller Elements
Authors: Gowda Siddarame , Ayllón María A. , Satyanarayana Tatineni , Bar-Joseph Moshe , Dawson William O. 
Published: December 2002

ABSTRACT

Citrus tristeza virus
(CTV) produces more than thirty 3′- or 5′-terminal subgenomic RNAs (sgRNAs) that accumulate to various extents during replication in protoplasts and plants. Among the most unusual species are two abundant populations of small 5′-terminal sgRNAs of approximately 800 nucleotides (nt) termed low-molecular-weight tristeza (LMT1 and LMT2) RNAs. Remarkably, CTV replicons with all 10 3′ genes deleted produce only the larger LMT1 RNAs. These 5′-terminal positive-sense sgRNAs do not have corresponding negative strands and were hypothesized to be produced by premature termination during plus-strand genomic RNA synthesis. We characterized a
cis
-acting element that controls the production of the LMT1 RNAs. Since manipulation of this
cis
-acting element in its native position (the L-ProI region of replicase) was not possible because the mutations negatively affect replication, a region (5′TR) surrounding the putative termination sites (nt ∼550 to 1000) was duplicated in the 3′ end of a CTV replicon to allow characterization. The duplicated sequence continued to produce a 5′-terminal plus-strand sgRNA, here much larger (∼11 kb), apparently by termination. Surprisingly, a new 3′-terminal sgRNA was observed from the duplicated 5′TR. A large 3′-terminal sgRNA resulting from the putative promoter activity of the native 5′TR was not observed, possibly because of the down-regulation of a promoter ∼19 kb from the 3′ terminus. However, we were able to observe a sgRNA produced from the native 5′TR of a small defective RNA, which placed the native 5′TR closer to the 3′ terminus, demonstrating sgRNA promoter activity of the native 5′TR. Deletion mutagenesis mapped the promoter and the terminator activities of the 5′TR (in the 3′ position in the CTV replicon) to a 57-nt region, which was folded by the MFOLD computer program into two stem-loops. Mutations in the putative stem-loop structures equally reduced or prevented production of both the 3′- and 5′-terminal sgRNAs. These mutations, when introduced in frame in the native 5′TR, similarly abolished the synthesis of the LMT1 RNAs and presumably the large 3′-terminal sgRNA while having no impact on replication, demonstrating that neither 5′- nor 3′-terminal sgRNA is necessary for replication of the replicon or full-length CTV in protoplasts. Differences between the 5′TR, which produced two plus-strand sgRNAs, and the
cis
-acting elements controlling the 3′ open reading frames, which produced additional minus-strand sgRNAs corresponding to the 3′-terminal mRNAs, suggest that the different sgRNA controller elements had different origins in the modular evolution of closteroviruses.