bluuebunny/crossref_metadata_2025_split huggingface dataset:
A GP64-Null Baculovirus Pseudotyped with Vesicular Stomatitis Virus G Protein
Authors: Mangor J. T. , Monsma S. A. , Johnson M. C. , Blissard G. W. 
Published: July 2002

ABSTRACT

The
Autographa californica
multiple nucleopolyhedrovirus (Ac
M
NPV) GP64 protein is an essential virion protein that is involved in both receptor binding and membrane fusion during viral entry. Genetic studies have shown that GP64-null viruses are unable to move from cell to cell and this results from a defect in the assembly and production of budded virions (BV). To further examine requirements for virion budding, we asked whether a GP64-null baculovirus, vAc
64−
, could be pseudotyped by introducing a heterologous viral envelope protein (vesicular stomatitis virus G protein [VSV-G]) into its membrane and whether the resulting virus was infectious. To address this question, we generated a stably transfected insect Sf9 cell line (Sf9
VSV-G
) that inducibly expresses the VSV-G protein upon infection with Ac
M
NPV Sf9
VSV-G
and Sf9 cells were infected with vAc
64−
, and cells were monitored for infection and for movement of infection from cell to cell. vAc
64−
formed plaques on Sf9
VSV-G
cells but not on Sf9 cells, and plaques formed on Sf9
VSV-G
cells were observed only after prolonged intervals. Passage and amplification of vAc
64−
on Sf9
VSV-G
cells resulted in pseudotyped virus particles that contained the VSV-G protein. Cell-to-cell propagation of vAc
64−
in the G-expressing cells was delayed in comparison to wild-type (wt) Ac
M
NPV, and growth curves showed that pseudotyped vAc
64−
was generated at titers of approximately 10
6
to 10
7
infectious units (IU)/ml, compared with titers of approximately 10
8
IU/ml for wt Ac
M
NPV. Propagation and amplification of pseudotyped vAc
64−
virions in Sf9
VSV-G
cells suggests that the VSV-G protein may either possess the signals necessary for baculovirus BV assembly and budding at the cell surface or may otherwise facilitate production of infectious baculovirus virions. The functional complementation of GP64-null viruses by VSV-G protein was further demonstrated by identification of a vAc
64−
-derived virus that had acquired the G gene through recombination with Sf9
VSV-G
cellular DNA. GP64-null viruses expressing the VSV-G gene were capable of productive infection, replication, and propagation in Sf9 cells.
Antiviral Response in Cells Containing Stat1 with Heterologous Transactivation Domains
Authors: Shen Yuhong , Darnell James E. 
Published: July 2002

ABSTRACTThe STATs (signal transducers and activators of transcription), latent cytoplasmic transcription factors, are activated by binding of extracellular polypeptides to cell surface receptors. Dimerization, accumulation in the nucleus, and transcriptional inductions of specific genes then occur. The COOH terminus of the STATs acts as a transcriptional activation domain (TAD). Stat1, one of seven mammalian STAT genes, forms a homodimer after activation by gamma interferon and induces transcription of a number of genes. These induced genes in turn produce the antiviral state. In the present experiments we used a Stat1-deficient cell line complemented with Stat1 or various fusion constructs in which the wild-type Stat1 TAD was replaced by other TADs to test the possibility that a specific activating domain was necessary for the induction of the antiviral response. We found that a wide variety of TADs with different activation potential appended to the Stat1 COOH terminus could substitute for the wild-type protein in inducing the antiviral state.
Evolutionary Relationships among Parvoviruses: Virus-Host Coevolution among Autonomous Primate Parvoviruses and Links between Adeno-Associated and Avian Parvoviruses
Authors: Lukashov Vladimir V. , Goudsmit Jaap 
Published: July 2002

ABSTRACT

The current classification of parvoviruses is based on virus host range and helper virus dependence, while little data on evolutionary relationships among viruses are available. We identified and analyzed 472 sequences of parvoviruses, among which there were (virtually) full-length genomes of all 41 viruses currently recognized as individual species within the family
Parvoviridae
. Our phylogenetic analysis of full-length genomes as well as open reading frames distinguished three evolutionary groups of parvoviruses from vertebrates: (i) the human helper-dependent adeno-associated virus (AAV) serotypes 1 to 6 and the autonomous avian parvoviruses; (ii) the bovine, chipmunk, and autonomous primate parvoviruses, including human viruses B19 and V9; and (iii) the parvoviruses from rodents (except for chipmunks), carnivores, and pigs. Each of these three evolutionary groups could be further subdivided, reflecting both virus-host coevolution and multiple cross-species transmissions in the evolutionary history of parvoviruses. No parvoviruses from invertebrates clustered with vertebrate parvoviruses. Our analysis provided evidence for negative selection among parvoviruses, the independent evolution of their genes, and recombination among parvoviruses from rodents. The topology of the phylogenetic tree of autonomous human and simian parvoviruses matched exactly the topology of the primate family tree, as based on the analysis of primate mitochondrial DNA. Viruses belonging to the AAV group were not evolutionarily linked to other primate parvoviruses but were linked to the parvoviruses of birds. The two lineages of human parvoviruses may have resulted from independent ancient zoonotic infections. Our results provide an argument for reclassification of
Parvovirinae
based on evolutionary relationships among viruses.
Linkage between STAT Regulation and Epstein-Barr Virus Gene Expression in Tumors
Authors: Chen Honglin , Lee Jae Myun , Zong Yongsheng , Borowitz Michael , Ng Mun Hon , Ambinder Richard F. , Hayward S. Diane 
Published: July 2002

ABSTRACTEpstein-Barr virus (EBV) latency gene expression in lymphoblastoid cell lines is regulated by EBNA2. However, the factors regulating viral expression in EBV-associated tumors that do not express EBNA2 are poorly understood. In EBV-associated tumors, EBNA1 and frequently LMP1 are synthesized. We found that an alternative latent membrane protein 1 (LMP1) promoter, L1-TR, located within the terminal repeats is active in both nasopharyngeal carcinoma and Hodgkin's disease tissues. Examination of the L1-TR and the standard ED-L1 LMP1 promoters in electrophoretic mobility shift assays revealed that both promoters contain functional STAT binding sites. Further, both LMP1 promoters responded in reporter assays to activation of JAK-STAT signaling. Cotransfection of JAK1 or v-Src or treatment of cells with the cytokine interleukin-6 upregulated expression from ED-L1 and L1-TR reporter plasmids. Cotransfection of a dominant negative STAT3β revealed that STAT3 is likely to be the biologically relevant STAT for EBNA1 Qp and LMP1 L1-TR promoter regulation. In contrast, LMP1 expression from ED-L1 was not abrogated by STAT3β, indicating that the two LMP1 promoters are regulated by different STAT family members. Taken together with the previous demonstration of JAK-STAT activation of Qp driven EBNA1 expression, this places two of the EBV genes most commonly expressed in tumors under the control of the same signal transduction pathway. Immunohistochemical analyses of nasopharyngeal carcinoma tumors revealed that STAT3, STAT5, and STAT1 are constitutively activated in these tumors while STAT3 is constitutively activated in the malignant cells of Hodgkin's disease. We hypothesize that chronic or aberrant STAT activation may be both a necessary and predisposing event for EBV-driven tumorigenesis in immunocompetent individuals.
Roles of Macrophages in Measles Virus Infection of Genetically Modified Mice
Authors: Roscic-Mrkic Branka , Schwendener Reto A. , Odermatt Bernhard , Zuniga Armando , Pavlovic Jovan , Billeter Martin A. , Cattaneo Roberto 
Published: July 2002

ABSTRACTKnowledge of the mechanisms of virus dissemination in acute measles is cursory, but cells of the monocyte/macrophage (MM) lineage appear to be early targets. We characterized the dissemination of the Edmonston B vaccine strain of measles virus (MV-Ed) in peripheral blood mononuclear cells (PBMC) of two mouse strains expressing the human MV-Ed receptor CD46 with human-like tissue specificity and efficiency. In one strain the alpha/beta interferon receptor is defective, allowing for efficient MV-Ed systemic spread. In both mouse strains the PBMC most efficiently infected were F4/80-positive MMs, regardless of the inoculation route used. Circulating B lymphocytes and CD4-positive T lymphocytes were infected at lower levels, but no infected CD8-positive T lymphocytes were detected. To elucidate the roles of MMs in infection, we depleted these cells by clodronate liposome treatment in vivo. MV-Ed infection of splenic MM-depleted mice caused strong activation and infection of splenic dendritic cells (DC), followed by enhanced virus replication in the spleen. Similarly, depletion of lung macrophages resulted in strong activation and infection of lung DC. Thus, in MV infections of genetically modified mice, blood monocytes and tissue macrophages provide functions beneficial for both the virus and the host: they support virus replication early after infection, but they also contribute to protecting other immune cells from infection. Human MM may have similar roles in acute measles.
RGD Tripeptide of Bluetongue Virus VP7 Protein Is Responsible for Core Attachment to
Culicoides
Cells
Authors: Tan Boon-Huan , Nason Emma , Staeuber Norbert , Jiang Wenrong , Monastryrskaya Katherine , Roy Polly 
Published: July 2002

ABSTRACT

Bluetongue virus (BTV) is an arthropod-borne virus transmitted by
Culicoides
species to vertebrate hosts. The double-capsid virion is infectious for
Culicoides
vector and mammalian cells, while the inner core is infectious for only
Culicoides
-derived cells. The recently determined crystal structure of the BTV core has revealed an accessible RGD motif between amino acids 168 to 170 of the outer core protein VP7, whose structure and position would be consistent with a role in cell entry. To delineate the biological role of the RGD sequence within VP7, we have introduced point mutations in the RGD tripeptide and generated three recombinant baculoviruses, each expressing a mutant derivative of VP7 (VP7-AGD, VP7-ADL, and VP7-AGQ). Each expressed mutant protein was purified, and the oligomeric nature and secondary structure of each was compared with those of the wild-type (wt) VP7 molecule. Each mutant VP7 protein was used to generate empty core-like particles (CLPs) and were shown to be biochemically and morphologically identical to those of wt CLPs. However, when mutant CLPs were used in an in vitro cell binding assay, each showed reduced binding to
Culicoides
cells compared to wt CLPs. Twelve monoclonal antibodies (MAbs) was generated using purified VP7 or CLPs as a source of antigen and were utilized for epitope mapping with available chimeric VP7 molecules and the RGD mutants. Several MAbs bound to the RGD motif on the core, as shown by immunogold labeling and cryoelectron microscopy. RGD-specific MAb H1.5, but not those directed to other regions of the core, inhibited the binding activity of CLPs to the
Culicoides
cell surface. Together, these data indicate that the RGD motif present on BTV VP7 is responsible for
Culicoides
cell binding activity.
Binding of LFA-1 (CD11a) to Intercellular Adhesion Molecule 3 (ICAM-3; CD50) and ICAM-2 (CD102) Triggers Transmigration of Human Immunodeficiency Virus Type 1-Infected Monocytes through Mucosal Epithelial Cells
Authors: Carreno Marie-Paule , Chomont Nicolas , Kazatchkine Michel D. , Irinopoulou Theano , Krief Corrine , Mohamed Ali-Si , Andreoletti Laurent , Matta Mathieu , Belec Laurent 
Published: July 2002

ABSTRACTTransmigration of human immunodeficiency virus (HIV)-infected mononuclear cells through the genital mucosa is one of the possible mechanisms of sexual transmission of HIV. Here, we investigated the transmigration of cell-associated R5-tropic HIV type 1 (HIV-1) through a tight monolayer of human epithelial cells in vitro. We show that this process is dependent on an initial interaction between αLβ2 integrin CD11a/CD18 on infected monocytic cells and intercellular adhesion molecule 2 (ICAM-2; CD102) and ICAM-3 (CD50) on the apical membrane of epithelial cells. The CD50 and CD102 ligands were overexpressed on epithelial cells when the cells were activated by proinflammatory cytokines in the cellular microenvironment. An accumulation of proviral DNA was found in the transmigrated cells, clearly reflecting the preferential transepithelial migration of HIV-1-infected cells under proinflammatory conditions. Our observations provide new insights supporting the hypothesis that HIV-infected mononuclear cells contained in genital secretions from infected individuals may cross the epithelial genital mucosa of an exposed receptive sexual partner, particularly under inflammatory conditions of damaged genital tissue. Understanding the fundamental aspects of the initial HIV entry process during sexual transmission remains a critical step for preventing human infection and developing further vaccinal strategies and virucidal agents.
Molecular Epidemiology of Human Immunodeficiency Virus Type 1 Transmission in a Heterosexual Cohort of Discordant Couples in Zambia
Authors: Trask Stanley A. , Derdeyn Cynthia A. , Fideli Ulgen , Chen Yalu , Meleth Sreelatha , Kasolo Francis , Musonda Rosemary , Hunter Eric , Gao Feng , Allen Susan , Hahn Beatrice H. 
Published: July 2002

ABSTRACT

Most human immunodeficiency virus type 1 (HIV-1) transmissions in sub-Saharan Africa are believed to occur between married adults who are discordant for their HIV-1 infection status; however, no studies to date have investigated the molecular epidemiology of such transmission events. Here we report the genetic characterization of HIV-1 strains from 149 transmission pairs that were identified prospectively in a cohort of discordant couples in Lusaka, Zambia. Subgenomic
gag
, gp120, gp41, and/or long terminal repeat regions were amplified by PCR analysis of uncultured blood samples from both partners and sequenced without interim cloning. Pairwise genetic distances were calculated for the regions analyzed and compared to those of subtype-specific reference sequences as well as local controls. Sequence relationships were also examined by phylogenetic tree analysis. By these approaches, epidemiological linkage was established for the majority of transmission pairs. Viruses from 129 of the 149 couples (87%) were very closely related and clustered together in phylogenetic trees in a statistically highly significant manner. In contrast, viruses from 20 of the 149 couples (13%) were only distantly related in two independent genomic regions, thus ruling out transmission between the two partners. The great majority (95%) of transmitted viruses were of subtype C origin, although representatives of subtypes A, D, G, and J were also identified. There was no evidence for extensive transmission networks within the cohort, although two phylogenetic subclusters of viruses infecting two couples each were identified. Taken together, these data indicate that molecular epidemiological analyses of presumed transmission pairs are both feasible and required to determine behavioral, virological, and immunological correlates of heterosexual transmission in sub-Saharan Africa with a high level of accuracy.
Retrograde Transport of Transmissible Mink Encephalopathy within Descending Motor Tracts
Authors: Bartz Jason C. , Kincaid Anthony E. , Bessen Richard A. 
Published: July 2002

ABSTRACTThe spread of the abnormal conformation of the prion protein, PrPSc, within the spinal cord is central to the pathogenesis of transmissible prion diseases, but the mechanism of transport has not been determined. For this report, the route of transport of the HY strain of transmissible mink encephalopathy (TME), a prion disease of mink, in the central nervous system following unilateral inoculation into the sciatic nerves of Syrian hamsters was investigated. PrPScwas detected at 3 weeks postinfection in the lumbar spinal cord and ascended to the brain at a rate of approximately 3.3 mm per day. At 6 weeks postinfection, PrPScwas detected in the lateral vestibular nucleus and the interposed nucleus of the cerebellum ipsilateral to the site of sciatic nerve inoculation and in the red nucleus contralateral to HY TME inoculation. At 9 weeks postinfection, PrPScwas detected in the contralateral hind limb motor cortex and reticular thalamic nucleus. These patterns of PrPScbrain deposition at various times postinfection were consistent with that of HY TME spread from the sciatic nerve to the lumbar spinal cord followed by transsynaptic spread and retrograde transport to the brain and brain stem along descending spinal tracts (i.e., lateral vestibulospinal, rubrospinal, and corticospinal). The absence of PrPScfrom the spleen suggested that the lymphoreticular system does not play a role in neuroinvasion following sciatic nerve infection. The rapid disease onset following sciatic nerve infection demonstrated that HY TME can spread by retrograde transport along specific descending motor pathways of the spinal cord and, as a result, can initially target brain regions that control vestibular and motor functions. The early clinical symptoms of HY TME infection such as head tremor and ataxia were consistent with neuronal damage to these brain areas.
Intracutaneous DNA Vaccination with the E8 Gene of Cottontail Rabbit Papillomavirus Induces Protective Immunity against Virus Challenge in Rabbits
Authors: Hu Jiafen , Han Ricai , Cladel Nancy M. , Pickel Martin D. , Christensen Neil D. 
Published: July 2002

ABSTRACT

The cottontail rabbit papillomavirus (CRPV)-rabbit model has been used in several studies for testing prophylactic and therapeutic papillomavirus vaccines. Earlier observations had shown that the CRPV nonstructural genes E1, E2, and E6 induced strong to partial protective immunity against CRPV infection. In this study, we found that CRPV E8 immunization eliminated virus-induced papillomas in EIII/JC inbred rabbits (100%) and provided partial protection (55%) against virus challenge in outbred New Zealand White rabbits. CRPV-E8 is a small open reading frame, coding for a 50-amino-acid protein, that is colinear with the CRPV E6 gene and has features similar to those of the bovine papillomavirus and human papillomavirus E5 genes. Papillomas that grew on E8-vaccinated outbred rabbits were significantly smaller than those on vector-vaccinated rabbits (
P
< 0.01;
t
test). Delayed-type hypersensitivity skin tests showed that some of the E8-vaccinated rabbits had positive responses to E8-specific peptides.
A Mutation in the Latency-Related Gene of Bovine Herpesvirus 1 Disrupts the Latency Reactivation Cycle in Calves
Authors: Inman Melissa , Lovato Luciane , Doster Alan , Jones Clinton 
Published: July 2002

ABSTRACT

Bovine herpesvirus 1 (BHV-1) is an important pathogen of cattle, and infection is usually initiated via the ocular or nasal cavity. Following acute infection, the primary site for BHV-1 latency is the sensory neuron. Reactivation from latency occurs sporadically, resulting in virus shedding and transmission to uninfected cattle. The only abundant viral transcript expressed during latency is the latency-related (LR) RNA, suggesting that it mediates some aspect of latency. An LR mutant was constructed by inserting three stop codons near the beginning of the LR-RNA, suggesting that expression of LR proteins would be altered. The LR mutant grew with wild-type (wt) efficiency in bovine kidney cells (MDBK). When calves were infected with the LR mutant, a dramatic decrease (3 to 4 logs) in ocular, but not nasal, viral shedding occurred during acute infection relative to the wt or the LR-rescued virus (M. Inman, L. Lovato, A. Doster, and C. Jones, J. Virol.
75:
8507-8515, 2001). In this study, we examined the latency reactivation cycle in calves infected with the LR mutant and compared these results to those from calves infected with wt BHV-1 or the LR-rescued virus. During acute infection, lower levels of infectious virus were detected in trigeminal ganglion homogenates from calves infected with the LR mutant. As judged by in situ hybridization, BHV-1-positive neurons were detected in trigeminal ganglia of calves infected with the wt but not the LR mutant. Although LR-RNA was detected by reverse transcription-PCR in calves latently infected with the LR mutant, a semiquantitative PCR analysis revealed that lower levels of viral DNA were present in trigeminal ganglia of calves infected with the LR mutant. Dexamethasone treatment of calves latently infected with wt BHV-1 or the LR-rescued virus, but not the LR mutant, consistently induced reactivation from latency, as judged by shedding of infectious virus from the nose or eyes and increases in BHV-1-specific antibodies. In summary, this study demonstrates that wt expression of LR gene products plays an important role in the latency reactivation cycle of BHV-1 in cattle.
Sequence Variation in a Newly Identified HLA-B35-Restricted Epitope in the Influenza A Virus Nucleoprotein Associated with Escape from Cytotoxic T Lymphocytes
Authors: Boon A. C. M. , de Mutsert G. , Graus Y. M. F. , Fouchier R. A. M. , Sintnicolaas K. , Osterhaus A. D. M. E. , Rimmelzwaan G. F. 
Published: July 2002

ABSTRACTHere, we describe a new HLA-B*3501-restricted cytotoxic T lymphocyte (CTL) epitope in the influenza A virus (H3N2) nucleoprotein, which was found to exhibit a high degree of variation at nonanchor residues. The influenza virus variants emerged in chronological order, and CTLs directed against old variants failed to recognize more recent strains of influenza A virus, indicating an escape from CTL immunity.
Contribution of Peaks of Virus Load to Simian Immunodeficiency Virus Pathogenesis
Authors: Regoes Roland R. , Staprans Silvija I. , Feinberg Mark B. , Bonhoeffer Sebastian 
Published: July 2002

ABSTRACTThe mechanisms causing AIDS and subsequently death in human immunodeficiency virus type 1 infection are not yet fully understood. Nonetheless, correlates of accelerated progression to disease based on immunological and virological markers have been identified. The best correlate identified to date is the baseline virus load or the so-called viral set point. By focusing on a virus load measurement from a restricted time range, however, we ignore valuable information contained in the long-term profile of the virus load. Here, we investigate the relationship between virus load and survival with the aid of a statistical model. The model takes into consideration the virus load at every stage of the disease. In particular, we aim to determine the effect of peaks of virus load on disease progression. We fit our model to unique sequential viral load data of 12 simian immunodeficiency virus mac251-infected rhesus macaques which contain frequent measurements throughout the entire course of the infection until the development of simian AIDS. Our model enables us to predict the survival times of the animals more accurately than an equivalent model which considers the viral set point only. Furthermore, we find that peaks of the virus load contribute less to disease progression than phases of low virus load with the same amount of viral turnover. Our analysis implies that the total viral turnover is not the best correlate of survival. As a consequence, the direct cytopathic effects of virus replication may, by themselves, have less of an impact on disease progression than previously thought.
A Study of Mesomorphous Properties of O-(2-Hydroxypropyl)cellulose Derivatives
Authors: Sroková Iva , Čík Gabriel , Hodul Pavel 
Published: July 2002

O-(2-Hydroxypropyl)cellulose has been used for synthesis of O-decyl-O-(2-hydroxypropyl)cellulose (DHPC; DS = 2.2) and O-stearoyl-O-(2-hydroxypropyl)cellulose (SHPC; DS = 2.1). Both compounds show mesomorphous properties of liquid polymeric crystals. DHPC in the form of highly viscous liquid has a lyotropic character. SHPC as solid has thermotropic properties with two phase transitions in the interval of 40 - 70 °C.