bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Common Integration Site, Int7, for the Mouse Mammary Tumor Virus in Mouse Mammary Tumors Identifies a Gene Whose Product Has Furin-Like and Thrombospondin-Like Sequences
Authors: Lowther William , Wiley Korah , Smith Gilbert H. , Callahan Robert 
Published: July 2005

ABSTRACT
A novel common integration site for the mouse mammary tumor virus (MMTV) was identified (designated Int7) in five independently arising mouse mammary tumors. The insertion sites all cluster within a 1-kb region that is 2 to 3 kb 5′ of the transcription initiation site of a gene, 2610028F08RIK, whose gene product contains furin-like and thrombospondin-like sequences. Expression of Int7 is normally very low or silent during various stages of mammary gland development, but MMTV integration at this site results in the activation of high steady-state levels of expression of the gene. These five tumors were also found to have two or three additional viral insertions, which in each case occurred flanking a member of either the Wnt and/or FGF gene family. Reverse transcriptase PCR results demonstrated that each of the viral insertions led to elevated expression of the presumed target flanking genes.
Important Roles for Gamma Interferon and NKG2D in γδ T-Cell-Induced Demyelination in T-Cell Receptor β-Deficient Mice Infected with a Coronavirus
Authors: Dandekar Ajai A. , O'Malley Katherine , Perlman Stanley 
Published: July 2005

ABSTRACTγδ T cells mediate demyelination in athymic (nude) mice infected with the neurotropic coronavirus mouse hepatitis virus strain JHM. Now, we show that these cells also mediate the same process in mice lacking αβ T cells (T-cell receptor β-deficient [TCRβ−/−] mice) and demyelination is gamma interferon (IFN-γ) dependent. Most strikingly, our results also show a major role for NKG2D, expressed on γδ T cells, in the demyelinating process with in vivo blockade of NKG2D interactions resulting in a 60% reduction in demyelination. NKG2D may serve as a primary recognition receptor or as a costimulatory molecule. We show that NKG2D+γδ T cells in the JHM-infected central nervous system express the adaptor molecule DAP12 and an NKG2D isoform (NKG2D short), both required for NKG2D to serve as a primary receptor. These results are consistent with models in which γδ T cells mediate demyelination using the same effector cytokine, IFN-γ, as CD8 T cells and do so without a requirement for signaling through the TCR.
Variant-Specific Tropism of Human Herpesvirus 6 in Human Astrocytes
Authors: Donati Donatella , Martinelli Elena , Cassiani-Ingoni Riccardo , Ahlqvist Jenny , Hou Jean , Major Eugene O. , Jacobson Steve 
Published: July 2005

ABSTRACT
Though first described as a lymphotropic virus, human herpesvirus 6 (HHV-6) is highly neuropathogenic. Two viral variants are known: HHV-6A and HHV-6B. Both variants can infect glial cells and have been differentially associated with central nervous system diseases, suggesting an HHV-6 variant-specific tropism for glial cell subtypes. We have performed infections with both viral variants in human progenitor-derived astrocytes (HPDA) and monitored infected cell cultures for cytopathic effect (CPE), intra- and extracellular viral DNA load, the presence of viral particles by electronic microscopy, mRNA transcription, and viral protein expression. HHV-6A established a productive infection with CPE, visible intracellular virions, and high virus DNA loads. HHV-6B-infected HPDA showed no morphological changes, intracellular viral particles, and decreasing intra- and extracellular viral DNA over time. After long-term passage, HHV-6B-infected HPDA had stable but low levels of intracellular viral DNA load with no detectable viral mRNA. Our results demonstrate that HHV-6A and HHV-6B have differential tropisms and patterns of infection for HPDA in vitro, where HHV-6A results in a productive lytic infection. In contrast, HHV-6B was associated with a nonproductive infection. These findings suggest that HHV-6 variants might be responsible for specific infection patterns in glial cells in vivo. Astrocytes may be an important reservoir for this virus in which differential tropism of HHV-6A and HHV-6B may be associated with different disease outcomes.
Human T-Lymphotropic Virus Type 1 Mitochondrion-Localizing Protein p13
II
Sensitizes Jurkat T Cells to Ras-Mediated Apoptosis
Authors: Hiraragi Hajime , Michael Bindhu , Nair Amrithraj , Silic-Benussi Micol , Ciminale Vincenzo , Lairmore Michael 
Published: July 2005

ABSTRACT

Human T-lymphotropic virus type 1 (HTLV-1) is the etiological agent of adult T-cell leukemia. In addition to typical retroviral structural and enzymatic gene products, HTLV-1 encodes unique regulatory and accessory proteins, including a singly spliced pX open reading frame II (ORF II) product, p13
II
. We have demonstrated that proviral clones of HTLV-1 which are mutated in pX ORF II fail to obtain typical proviral loads and antibody responses in a rabbit animal model. p13
II
localizes to mitochondria and reduces cell growth and tumorigenicity in mice, but its function in human lymphocytes remains undetermined. For this study, we analyzed the functional properties of Jurkat T cells expressing p13
II
, using both transient and stable expression vectors. Our data indicate that p13
II
-expressing Jurkat T cells are sensitive to caspase-dependent, ceramide- and FasL-induced apoptosis. p13
II
-expressing Jurkat T cells also exhibited reduced proliferation when cultured at a high density. Furthermore, preincubation of the p13
II
-expressing cells with a farnesyl transferase inhibitor, which blocks the posttranslational modification of Ras, markedly reduced FasL-induced apoptosis, indicating the participation of the Ras pathway in p13
II
's influence on lymphocyte survival. Our data are the first to demonstrate that p13
II
alters Ras-mediated apoptosis in T lymphocytes, and they reveal a potential mechanism by which HTLV-1 alters lymphocyte proliferation.
Apical Entry and Release of Severe Acute Respiratory Syndrome-Associated Coronavirus in Polarized Calu-3 Lung Epithelial Cells
Authors: Tseng Chien-Te K. , Tseng Jennifer , Perrone Lucy , Worthy Melissa , Popov Vsevolod , Peters Clarence J. 
Published: July 2005

ABSTRACT
Severe acute respiratory syndrome (SARS), caused by a novel coronavirus (CoV) known as SARS-CoV, is a contagious and life-threatening respiratory illness with pneumocytes as its main target. A full understanding of how SARS-CoV would interact with lung epithelial cells will be vital for advancing our knowledge of SARS pathogenesis. However, an in vitro model of SARS-CoV infection using relevant lung epithelial cells is not yet available, making it difficult to dissect the pathogenesis of SARS-CoV in the lungs. Here, we report that SARS-CoV can productively infect human bronchial epithelial Calu-3 cells, causing cytopathic effects, a process reflective of its natural course of infection in the lungs. Indirect immunofluorescence studies revealed a preferential expression of angiotensin-converting enzyme 2 (ACE-2), the functional receptor of SARS-CoV, on the apical surface. Importantly, both ACE-2 and viral antigen appeared to preferentially colocalize at the apical domain of infected cells. In highly polarized Calu-3 cells grown on the membrane inserts, we found that cells exposed to virus through the apical rather than the basolateral surface showed high levels of viral replication. Progeny virus was released into the apical chamber at titers up to 5 logs higher than those recovered from the basolateral chambers of polarized cultures. Taken together, these results indicate that SARS-CoV almost exclusively entered and was released from the apical domain of polarized Calu-3 cells, which might provide important insight into the mechanism of transmission and pathogenesis of SARS-CoV.
Expression of Interleukin-4 by Recombinant Respiratory Syncytial Virus Is Associated with Accelerated Inflammation and a Nonfunctional Cytotoxic T-Lymphocyte Response following Primary Infection but Not following Challenge with Wild-Type Virus
Authors: Bukreyev Alexander , Belyakov Igor M. , Prince Gregory A. , Yim Kevin C. , Harris Katie K. , Berzofsky Jay A. , Collins Peter L. 
Published: July 2005

ABSTRACTThe outcome of a viral infection or of immunization with a vaccine can be influenced by the local cytokine environment. In studies of experimental vaccines against respiratory syncytial virus (RSV), an increased stimulation of Th2 (T helper 2) lymphocytes was associated with increased immunopathology upon subsequent RSV infection. For this study, we investigated the effect of increased local expression of the Th2 cytokine interleukin-4 (IL-4) from the genome of a recombinant RSV following primary infection and after a challenge with wild-type (wt) RSV. Mice infected with RSV/IL-4 exhibited an accelerated pulmonary inflammatory response compared to those infected with wt RSV, although the wt RSV group caught up by day 8. In the first few days postinfection, RSV/IL-4 was associated with a small but significant acceleration in the expansion of pulmonary T lymphocytes specific for an RSV CD8+cytotoxic T-lymphocyte (CTL) epitope presented as a major histocompatibility complex class I tetramer. However, by day 7 the response of tetramer-positive T lymphocytes in the wt RSV group caught up and exceeded that of the RSV/IL-4 group. At all times, the CTL response of the RSV/IL-4 group was deficient in the production of gamma interferon and was nonfunctional for in vitro cell killing. The accelerated inflammatory response coincided with an accelerated accumulation and activation of pulmonary dendritic cells early in infection, but thereafter the dendritic cells were deficient in the expression of B7-1, which governs the acquisition of cytolytic activity by CTL. Following a challenge with wt RSV, there was an increase in Th2 cytokines in the animals that had previously been infected with RSV/IL-4 compared to those previously infected with wt RSV, but the CD8+CTL response and the amount of pulmonary inflammation were not significantly different. Thus, a strong Th2 environment during primary pulmonary immunization with live RSV resulted in early inflammation and a largely nonfunctional primary CTL response but had a minimal effect on the secondary response.
CD4+T-Cell Reconstitution Reduces Cytomegalovirus in the Immunocompromised Brain
Authors: Reuter Jon D. , Wilson Jean H. , Idoko Kimberly E , van den Pol Anthony N. 
Published: July 2005

ABSTRACTCytomegalovirus (CMV) infection is the most common opportunistic infection of the central nervous system in patients with human immunodeficiency virus or AIDS or on immunosuppressive drug therapy. Despite medical management, infection may be refractory to treatment and continues to cause significant morbidity and mortality. We investigated adoptive transfer as an approach to treat and prevent neurotropic CMV infection in an adult immunodeficient mouse model. SCID mice were challenged with intracranial murine CMV (MCMV) and reconstituted with MCMV- or vesicular stomatitis virus (VSV)-sensitized splenocytes, T cells, or T-cell subsets. T cells labeled with vital dye or that constitutively generated green fluorescent protein (GFP) were identified in the brain as early as 3 days following peripheral transfer. Regardless of specificity, activated T cells localized to regions of the brain containing CMV, however, only those specific for CMV were effective at clearing virus. Reconstitution with unsorted MCMV-immune splenocytes, enriched T-cell fractions, or CD4+cells significantly reduced virus levels in the brain within 7 days and also prevented clinical disease, in significant contrast with mice given VSV-immune unsorted splenocytes, MCMV-immune CD8+T cells, and SCID control mice. Results suggest CMV-immune T cells (particularly CD4+) rapidly cross the blood-brain barrier, congregate at sites of specific CMV infection, and functionally eliminate acute CMV within the brain. In addition, when CMV-immune splenocytes were administered prior to a peripheral CMV challenge, CMV entry into the immunocompromised brain was prevented. Systemic adoptive transfer may be a rapid and effective approach to preventing CMV entrance into the brain and for reducing neurotropic infection.
Evidence that Low-Level Viremias during Effective Highly Active Antiretroviral Therapy Result from Two Processes: Expression of Archival Virus and Replication of Virus
Authors: Tobin Nicole H. , Learn Gerald H. , Holte Sarah E. , Wang Yang , Melvin Ann J. , McKernan Jennifer L. , Pawluk Diane M. , Mohan Kathleen M. , Lewis Paul F. , Mullins James I. , Frenkel Lisa M. 
Published: July 2005

ABSTRACT
Episodes of low-level viremia (LLV), with plasma human immunodeficiency virus type 1 (HIV-1) RNA levels ranging from 50 to 400 copies (c)/ml, occur commonly during highly active antiretroviral therapy (HAART). LLV has been associated with virologic failure of HAART in some studies, while in others LLV did not appear to affect the clinical outcome. To understand the processes leading to LLV, genetic analyses were used to determine whether plasma virions emanated from archived or from newly evolved viral genomes. Episodes of LLV (plasma HIV-1 RNA, 50 to 379 [median, 77] c/ml) were detected in 21/37 (57%) HIV-1-infected children with median plasma HIV-1 RNA levels of <50 c/ml during 79 patient years of HAART. Viral sequences were derived by direct sequencing of PCR products from 21 plasma specimens diluted to end point. In phylogenetic analysis, LLV viral sequences grouped with virus from early in the course of infection in 8/11 subjects. Six specimens had multiple identical viral sequences, suggesting origin from clonally expanded infected cells. LLV plasma virus evolved over time, indicating viral replication, in 3/11 subjects. Two of these had frequent LLV, including the selection of drug-resistant mutants. In summary, plasma virus from episodes of LLV during effective HAART appeared to originate from two distinct processes, (i) clonal outgrowth from long-lived HIV-1-infected cells, presumably following activation and proliferation of these cells, and (ii) ongoing viral replication that included the selection of new drug-resistant mutants. These observations provide a plausible explanation for the divergent clinical outcomes previously associated with LLV.
Mechanism of Stimulation of Plus-Strand Synthesis by an RNA Replication Enhancer in a Tombusvirus
Authors: Panavas Tadas , Nagy Peter D. 
Published: July 2005

ABSTRACT

Replication of RNA viruses is regulated by
cis
-acting RNA elements, including promoters, replication silencers, and replication enhancers (REN). To dissect the function of an REN element involved in plus-strand RNA synthesis, we developed an in vitro
trans
-replication assay for tombusviruses, which are small plus-strand RNA viruses. In this assay, two RNA strands were tethered together via short complementary regions with the REN present in the nontemplate RNA, whereas the promoter was located in the template RNA. We found that the template activity of the tombusvirus replicase preparation was stimulated in
trans
by the REN, suggesting that the REN is a functional enhancer when located in the vicinity of the promoter. In addition, this study revealed that the REN has dual function during RNA synthesis. (i) It binds to the viral replicase. (ii) It interacts with the core plus-strand initiation promoter via a long-distance RNA-RNA interaction, which leads to stimulation of initiation of plus-strand RNA synthesis by the replicase in vitro. We also observed that this RNA-RNA interaction increased the in vivo accumulation and competitiveness of defective interfering RNA, a model template. We propose that REN is important for asymmetrical viral RNA replication that leads to more abundant plus-strand RNA progeny than the minus-strand intermediate, a hallmark of replication of plus-strand RNA viruses.
Diversity, Divergence, and Evolution of Cell-Free Human Immunodeficiency Virus Type 1 in Vaginal Secretions and Blood of Chronically Infected Women: Associations with Immune Status
Authors: Sullivan Sharon T. , Mandava Usha , Evans-Strickfaden Tammy , Lennox Jeffrey L. , Ellerbrock Tedd V. , Hart Clyde E. 
Published: July 2005

ABSTRACT

Most human immunodeficiency virus type 1 (HIV-1) infections are believed to be the result of exposure to the virus in genital secretions. However, prevention and therapeutic strategies are usually based on characterizations of HIV-1 in blood. To understand better the dynamics between HIV-1 quasispecies in the genital tract and blood, we performed heteroduplex assays on amplified
env
products from cell-free viral RNA in paired vaginal secretion (VS) and blood plasma (BP) samples of 14 women followed for 1.5 to 3.5 years. Diversity and divergence were less in VS than in BP (
P
= 0.03 and
P
< 0.01, respectively), and divergence at both sites was correlated with blood CD4
+
cell levels (VS,
P
= 0.05; BP,
P
= 0.01). Evolution of quasispecies was observed in 58% of the women; the loss or gain of quasispecies in VS or BP was always accompanied by such changes at the other site. In addition, sustained compartmentalization of quasispecies in VS was found for four women, even as CD4
+
cell levels decreased to low levels (<50 cells/μl). Quasispecies changes over time were associated with fluctuations in CD4
+
cell levels; concordant increases or decreases in VS and BP divergence had greater CD4
+
cell level changes than intervals with discordant changes (
P
= 0.05), and women with evolving quasispecies had greater decreases in CD4
+
cell levels compared to that for women who maintained the same quasispecies (
P
< 0.05). Thus, diversity, divergence, and evolution of cell-free HIV-1 in VS can be different from that in BP, and dynamics between their respective quasispecies are associated with changes in CD4
+
cell levels.
Human Immunodeficiency Virus Reactivation by Phorbol Esters or T-Cell Receptor Ligation Requires both PKCα and PKCθ
Authors: Trushin Sergey A. , Bren Gary D. , Asin Susana , Pennington Kevin N. , Paya Carlos V. , Badley Andrew D. 
Published: July 2005

ABSTRACTLatently human immunodeficiency virus (HIV)-infected memory CD4+T cells represent the major obstacle to eradicating HIV from infected patients. Antigens, T-cell receptor (TCR) ligation, and phorbol esters can reactivate HIV from latency in a protein kinase C (PKC)-dependent manner; however, it is unknown which specific PKC isoforms are required for this effect. We demonstrate that constitutively active (CA) forms of both PKCθ, PKCθA148E, and PKCα, PKCαA25E, induce HIV long terminal repeat (LTR)-dependent transcription in Jurkat and primary human CD4+T cells and that both PKCθA148E and PKCαA25E cause HIV reactivation in J1.1 T cells. Suppression of both PKCα and PKCθ with short hairpinned (sh) RNA inhibited CD3/CD28-induced HIV LTR-dependent transcription and HIV reactivation in J1.1 T cells. Both prostratin and phorbol myristate 13-acetate induced HIV LTR-dependent transcription and HIV reactivation in J1.1 T cells that was blocked by shRNA against either PKCα or PKCθ. Since suppression of PKCα and PKCθ together has no greater inhibitory effect on HIV reactivation than inhibition of PKCα alone, our data confirm that PKCα and PKCθ act in sequence. The requirement for PKCα and PKCθ for prostratin-induced HIV reactivation and the ability of selective PKCα or PKCθ agonists to induce HIV transcription indicate that these PKC isoforms are important targets for therapeutic drug design.
A Peptide Derived from RNA Recognition Motif 2 of Human La Protein Binds to Hepatitis C Virus Internal Ribosome Entry Site, Prevents Ribosomal Assembly, and Inhibits Internal Initiation of Translation
Authors: Pudi Renuka , Ramamurthy Sudhamani S. , Das Saumitra 
Published: July 2005

ABSTRACT
Human La protein is known to interact with hepatitis C virus (HCV) internal ribosome entry site (IRES) and stimulate translation. Previously, we demonstrated that mutations within HCV SL IV lead to reduced binding to La-RNA recognition motif 2 (RRM2) and drastically affect HCV IRES-mediated translation. Also, the binding of La protein to SL IV of HCV IRES was shown to impart conformational alterations within the RNA so as to facilitate the formation of functional initiation complex. Here, we report that a synthetic peptide, LaR2C, derived from the C terminus of La-RRM2 competes with the binding of cellular La protein to the HCV IRES and acts as a dominant negative inhibitor of internal initiation of translation of HCV RNA. The peptide binds to the HCV IRES and inhibits the functional initiation complex formation. An Huh7 cell line constitutively expressing a bicistronic RNA in which both cap-dependent and HCV IRES-mediated translation can be easily assayed has been developed. The addition of purified TAT-LaR2C recombinant polypeptide that allows direct delivery of the peptide into the cells showed reduced expression of HCV IRES activity in this cell line. The study reveals valuable insights into the role of La protein in ribosome assembly at the HCV IRES and also provides the basis for targeting ribosome-HCV IRES interaction to design potent antiviral therapy.
Characterization of Immune Responses Induced by Intramuscular Vaccination with DNA Vaccines Encoding Measles Virus Hemagglutinin and/or Fusion Proteins
Authors: Song Man Ki , Vindurampulle Christofer J. , Capozzo Alejandra V. E. , Ulmer Jeffrey , Polo John M. , Pasetti Marcela F. , Barry Eileen M. , Levine Myron M. 
Published: July 2005

ABSTRACT
Measles virus (MV) hemagglutinin (MV-H) and fusion (MV-F) proteins induce plaque reduction neutralizing (PRN) antibodies and cell-mediated immune responses that protect against clinical measles. DNA vaccines that encode MV-H and MV-F are being investigated as a new generation of measles vaccine to protect infants too young to receive currently licensed attenuated measles vaccines. However, it is unclear whether DNA vaccines encoding both MV-H and MV-F act synergistically to induce stronger immunity than immunization with plasmids encoding MV-H or MV-F alone. To address this question, we generated Sindbis virus-based pSINCP DNA vaccines that encode either MV-H or MV-F alone or bicistronic or fusion system vectors that encode both MV-H and MV-F (to mimic MV infection where both MV-H and MV-F proteins are expressed by the same mammalian cell). Mice immunized with DNA vaccine encoding MV-H alone developed significantly greater PRN titers than mice immunized with bicistronic constructs. Interestingly, the presence of MV-F in the bicistronic constructs stimulated serum MV-specific immunoglobulin G of reduced avidity. By contrast, mice immunized with bicistronic constructs induced equivalent or higher levels of MV-specific gamma interferon responses than mice immunized with DNA vaccine encoding MV-H alone. These data will help guide the design of DNA-based MV vaccines to be used early in life in a heterologous prime-boost strategy.