bluuebunny/crossref_metadata_2025_split huggingface dataset:
Foamy Virus Integration
Authors: Juretzek Thomas , Holm Teresa , Gärtner Kathleen , Kanzler Sylvia , Lindemann Dirk , Herchenröder Ottmar , Picard-Maureau Marcus , Rammling Matthias , Heinkelein Martin , Rethwilm Axel 
Published: February 2004

ABSTRACT
It had been suggested that during integration of spumaretroviruses (foamy viruses) the right (U5) end of the cDNA is processed, while the left (U3) remains uncleaved. We confirmed this hypothesis by sequencing two-long terminal repeat (LTR) circle junctions of unintegrated DNA. Based on an infectious foamy virus molecular clone, a set of constructs harboring mutations at the 5′ end of the U3 region in the 3′ LTR was analyzed for particle export, reverse transcription, and replication. Following transient transfection some mutants were severely impaired in generating infectious virus, while others replicated almost like the wild type. The replication competence of the mutants was unrelated to the cleavability of the newly created U3 end. This became obvious with two mutants both belonging to the high-titer type. One mutant containing a dinucleotide artificially transferred from the right to the left end was trimmed upon integration, while another one with an unrelated dinucleotide in that place was not. The latter construct in particular showed that the canonical TG motif at the beginning of the provirus is not essential for foamy virus integration.
Influence of Long Terminal Repeat and Env on the Virulence Phenotype of Equine Infectious Anemia Virus
Authors: Payne Susan L. , Pei Xiao-fang , Jia Bin , Fagerness Angela , Fuller Frederick J. 
Published: February 2004

ABSTRACT

The molecular clones pSPeiav19 and p19/wenv17 of equine infectious anemia virus (EIAV) differ in
env
and long terminal repeats (LTRs) and produce viruses (EIAV
19
and EIAV
17
, respectively) of dramatically different virulence phenotypes. These constructs were used to generate a series of chimeric clones to test the individual contributions of LTR, surface (SU), and transmembrane (TM)/Rev regions to the disease potential of the highly virulent EIAV
17
. The LTRs of EIAV
19
and EIAV
17
differ by 16 nucleotides in the transcriptional enhancer region. The two viruses differ by 30 amino acids in SU, by 17 amino acids in TM, and by 8 amino acids in Rev. Results from in vivo infections with chimeric clones indicate that both LTR and
env
of EIAV
17
are required for the development of severe acute disease. In the context of the EIAV
17
LTR, SU appears to have a greater impact on virulence than does TM. EIAV
17SU
, containing only the TM/Rev region from the avirulent parent, induced acute disease in two animals, while a similar infectious dose of EIAV
17TM
(which derives SU from the avirulent parent) did not. Neither EIAV
17SU
nor EIAV
17TM
produced lethal disease when administered at infectious doses that were 6- to 30-fold higher than a lethal dose of the parental EIAV
17
. All chimeric clones replicated in primary equine monocyte-derived macrophages, and there was no apparent correlation between macrophage tropism and virulence phenotype.
Vaccinia Virus A36R Membrane Protein Provides a Direct Link between Intracellular Enveloped Virions and the Microtubule Motor Kinesin
Authors: Ward Brian M. , Moss Bernard 
Published: February 2004

ABSTRACT

Previous work demonstrated that intracellular enveloped vaccinia virus virions use microtubules to move from the site of membrane wrapping to the cell periphery. The mechanism and direction of intracellular virion movement predicted that viral proteins directly or indirectly interact with the microtubule motor protein kinesin. The yeast two-hybrid assay was used to test for interactions between the light chain of kinesin and the cytoplasmic tails from five viral envelope proteins. We found that the N-terminal tetratricopeptide repeat region of the kinesin light chain (KLC-TPR) interacted with the cytoplasmic tail of the viral A36R protein. A series of C- and N-terminal truncations of A36R further defined a region from residues 81 to 111 that was sufficient for interaction with KLC-TPR. Interactions were confirmed by using pull-down assays with purified glutathione
S
-transferase (GST)-A36R and
35
S-labeled KLC-TPR. The defined region on A36R for interaction with kinesin overlaps the recently defined region (residues 91 to 111) for interaction with the A33R envelope protein. The yeast three-hybrid system was used to demonstrate that expression of A33R interrupted the interaction between A36R and KLC-TPR, indicating that the binding of A36R is mutually exclusive to either A33R or kinesin. Pull-down assays with purified GST-A36R and
35
S-labeled KLC-TPR in the presence of competing A33R corroborated these findings. Collectively, these results demonstrated that the viral A36R protein interacts directly with the microtubule motor protein kinesin and that the viral protein A33R may regulate this interaction.
Identification of Exogenous Forms of Human-Tropic Porcine Endogenous Retrovirus in Miniature Swine
Authors: Wood James C. , Quinn Gary , Suling Kristen M. , Oldmixon Beth A. , Van Tine Brian A. , Cina Robert , Arn Scott , Huang Christine A. , Scobie Linda , Onions David E. , Sachs David H. , Schuurman Henk-Jan , Fishman Jay A. , Patience Clive 
Published: February 2004

ABSTRACT
The replication of porcine endogenous retrovirus subgroup A (PERV-A) and PERV-B in certain human cell lines indicates that PERV may pose an infectious risk in clinical xenotransplantation. We have previously reported that human-tropic PERVs isolated from infected human cells following cocultivation with miniature swine peripheral blood mononuclear cells (PBMC) are recombinants of PERV-A with PERV-C. Here, we report that these recombinants are exogenous viruses in miniature swine; i.e., they are not present in the germ line DNA. These viruses were invariably present in miniature swine that transmitted PERV to human cells and were also identified in some miniature swine that lacked this ability. These data, together with the demonstration of the absence of both replication-competent PERV-A and recombinant PERV-A/C loci in the genome of miniature swine (L. Scobie, S. Taylor, J. C. Wood, K. M. Suling, G. Quinn, C. Patience, H.-J. Schuurman, and D. E. Onions, J. Virol. 78:2502-2509, 2004), indicate that exogenous PERV is the principal source of human-tropic virus in these animals. Interestingly, strong expression of PERV-C in PBMC correlated with an ability of the PBMC to transmit PERV-A/C recombinants in vitro, indicating that PERV-C may be an important factor affecting the production of human-tropic PERV. In light of these observations, the safety of clinical xenotransplantation from miniature swine will be most enhanced by the utilization of source animals that do not transmit PERV to either human or porcine cells. Such animals were identified within the miniature swine herd and may further enhance the safety of clinical xenotransplantation.
Absence of Replication-Competent Human-Tropic Porcine Endogenous Retroviruses in the Germ Line DNA of Inbred Miniature Swine
Authors: Scobie Linda , Taylor Samantha , Wood James C. , Suling Kristen M. , Quinn Gary , Meikle Sharon , Patience Clive , Schuurman Henk-Jan , Onions David E. 
Published: February 2004

ABSTRACT

The potential transmission of porcine endogenous retroviruses (PERVs) has raised concern in the development of porcine xenotransplantation products. Our previous studies have resulted in the identification of animals within a research herd of inbred miniature swine that lack the capacity to transmit PERV to human cells in vitro. In contrast, other animals were capable of PERV transmission. The PERVs that were transmitted to human cells are recombinants between PERV-A and PERV-C in the post-VRA region of the envelope (B. A. Oldmixon, J. C. Wood, T. A. Ericsson, C. A. Wilson, M. E. White-Scharf, G. Andersson, J. L. Greenstein, H. J. Schuurman, and C. Patience, J. Virol.
76:
3045-3048, 2002); these viruses we term PERV-A/C. This observation prompted us to determine whether these human-tropic replication-competent (HTRC) PERV-A/C recombinants were present in the genomic DNA of these miniature swine. Genomic DNA libraries were generated from one miniature swine that transmitted HTRC PERV as well as from one miniature swine that did not transmit HTRC PERV. HTRC PERV-A/C proviruses were not identified in the germ line DNAs of these pigs by using genomic mapping. Similarly, although PERV-A loci were identified in both libraries that possessed long
env
open reading frames, the Env proteins encoded by these loci were nonfunctional according to pseudotype assays. In the absence of a germ line source for HTRC PERV, further studies are warranted to assess the mechanisms by which HTRC PERV can be generated. Once identified, it may prove possible to generate animals with further reduced potential to produce HTRC PERV.
A Virulence Factor of Myxoma Virus Colocalizes with NF-κB in the Nucleus and Interferes with Inflammation
Authors: Camus-Bouclainville Christelle , Fiette Laurence , Bouchiha Sophie , Pignolet Béatrice , Counor Dorian , Filipe Cédric , Gelfi Jacqueline , Messud-Petit Frédérique 
Published: February 2004

ABSTRACT

NF-κB is one of the most important elements that coordinate stress-induced, immune, and inflammatory responses.
Myxoma virus
, a member of the
Poxviridae
family responsible for rabbit myxomatosis, codes for several factors that help its survival in the host. In this study, we focused on the product of the M150R gene. We show that the protein has nine ankyrin repeats (ANKs), with the eighth having a close similarity with the nuclear localization signal-containing ANK of I-κBα, which regulates NF-κB activity by sequestering it in the cytosol. Because the viral protein is targeted to the nucleus, it was named MNF, for myxoma nuclear factor. This localization was lost when the eighth ANK was removed. In tumor necrosis factor alpha-treated cells, MNF and NF-κB colocalized as dotted spots in the nucleus. In vivo experiments with a knockout virus showed that MNF is a critical virulence factor, with its deletion generating an almost apathogenic virus. Detailed histological examinations revealed an increase in the inflammatory process in the absence of MNF, consistent with the interference of MNF with the NF-κB-induced proinflammatory pathway. Because MNF has homologs in other poxviruses, such as vaccinia, cowpox, and variola viruses, this protein is probably part of a key mechanism that contributes to the immunogenic and pathogenic properties of these viruses.
Inhibition of Human Immunodeficiency Virus Type 1 Replication by RNA Interference Directed against Human Transcription Elongation Factor P-TEFb (CDK9/CyclinT1)
Authors: Chiu Ya-Lin , Cao Hong , Jacque Jean-Marc , Stevenson Mario , Rana Tariq M. 
Published: February 2004

ABSTRACT
The human positive transcription elongation factor P-TEFb is composed of two subunits, cyclin T1 (hCycT1) and CDK9, and is involved in transcriptional regulation of cellular genes as well as human immunodeficiency virus type 1 (HIV-1) mRNA. Replication of HIV-1 requires the Tat protein, which activates elongation of RNA polymerase II at the HIV-1 promoter by interacting with hCycT1. To understand the cellular functions of P-TEFb and to test whether suppression of host proteins such as P-TEFb can modulate HIV infectivity without causing cellular toxicity or lethality, we used RNA interference (RNAi) to specifically knock down P-TEFb expression by degrading hCycT1 or CDK9 mRNA. RNAi-mediated gene silencing of P-TEFb in HeLa cells was not lethal and inhibited Tat transactivation and HIV-1 replication in host cells. We also found that CDK9 protein stability depended on hCycT1 protein levels, suggesting that the formation of P-TEFb CDK-cyclin complexes is required for CDK9 stability. Strikingly, P-TEFb knockdown cells showed normal P-TEFb kinase activity. Our studies suggest the existence of a dynamic equilibrium between active and inactive pools of P-TEFb in the cell and indicate that this equilibrium shifts towards the active kinase form to sustain cell viability when P-TEFb protein levels are reduced. The finding that a P-TEFb knockdown was not lethal and still showed normal P-TEFb kinase activity suggested that there is a critical threshold concentration of activated P-TEFb required for cell viability and HIV replication. These results provide new insights into the regulation of P-TEFb function and suggest the possibility that similar mechanisms for monitoring protein levels to modulate the activity of proteins may exist for the regulation of a variety of other enzymatic pathways.
In Vivo Role of Nectin-1 in Entry of Herpes Simplex Virus Type 1 (HSV-1) and HSV-2 through the Vaginal Mucosa
Authors: Linehan Melissa M. , Richman Susan , Krummenacher Claude , Eisenberg Roselyn J. , Cohen Gary H. , Iwasaki Akiko 
Published: February 2004

ABSTRACT
Herpes simplex virus type 2 (HSV-2) is transmitted through the genital mucosa during sexual encounters. In recent years, HSV-1 has also become commonly associated with primary genital herpes. The mechanism of viral entry of HSV-1 and HSV-2 in the female genital tract is unknown. In order to understand the molecular interactions required for HSV entry into the vaginal epithelium, we examined the expression of herpesvirus entry mediator nectin-1 in the vagina of human and mouse at different stages of their hormonal cycle. Nectin-1 was highly expressed in the epithelium of human vagina throughout the menstrual cycle, whereas the mouse vaginal epithelium expressed nectin-1 only during the stages of the estrous cycle in which mice are susceptible to vaginal HSV infection. Furthermore, the ability of nectin-1 to mediate viral entry following intravaginal inoculation was examined in a mouse model of genital herpes. Vaginal infection with either HSV-1 or HSV-2 was blocked by preincubation of the virus with soluble recombinant nectin-1. Viral entry through the vaginal mucosa was also inhibited by preincubation of HSV-2 with antibody against gD. Together, these results suggest the importance of nectin-1 in mediating viral entry for both HSV-1 and HSV-2 in the genital mucosa in female hosts.
Molecular Phylogenetic Analyses Indicate a Wide and Ancient Radiation of African Hepatitis Delta Virus, Suggesting a
Deltavirus
Genus of at Least Seven Major Clades
Authors: Radjef Nadjia , Gordien Emmanuel , Ivaniushina Valeria , Gault Elyanne , Anaïs Patricia , Drugan Tudor , Trinchet Jean-Claude , Roulot Dominique , Tamby Mathieu , Milinkovitch Michel C. , Dény Paul 
Published: February 2004

ABSTRACT
Hepatitis D virus (HDV) is a satellite of hepatitis B virus (HBV) for transmission and propagation and infects nearly 20 million people worldwide. The HDV genome is a compact circular single-stranded RNA genome with extensive intramolecular complementarity. Despite its different epidemiological and pathological patterns, the variability and geographical distribution of HDV are limited to three genotypes and two subtypes that have been characterized to date. Phylogenetic reconstructions based on the delta antigen gene and full-length genome sequence data show an extensive and probably ancient radiation of African lineages, suggesting that the genetic variability of HDV is much more complex than was previously thought, with evidence of additional clades. These results relate the geographic distribution of HDV more closely to the genetic variability of its helper HBV.
Immunization Strategies To Block the Herpes Simplex Virus Type 1 Immunoglobulin G Fc Receptor
Authors: Lin Xiaoqing , Lubinski John M. , Friedman Harvey M. 
Published: February 2004

ABSTRACTHerpes simplex virus type 1 (HSV-1) glycoprotein gE functions as an immunoglobulin G (IgG) Fc receptor (FcγR) that promotes immune evasion. When an IgG antibody binds by the F(ab′)2domain to an HSV antigen, the Fc domain of some of the same antibody molecules binds to the FcγR, which blocks Fc-mediated functions. gE is a type 1 membrane glycoprotein with a large ectodomain that is expressed on the virion envelope and infected-cell surface. Our goal was to determine if immunizing with gE protein fragments could produce antibodies that bind by the F(ab′)2domain to gE and block the FcγR, as measured by competitively inhibiting nonimmune human IgG binding to the FcγR. Three gE peptides were constructed in baculovirus spanning almost the entire ectodomain and used to immunize mice and rabbits. Two fragments were highly effective at producing antibodies that bind by the F(ab′)2domain and block the FcγR. The most potent of these two antibodies was far more effective at blocking the FcγR than antibodies that are only capable of binding by the Fc domains to the FcγR, including anti-gC, anti-gD, and nonimmune IgG. These results suggest that immunizing with gE fragments has potential for preventing immune evasion by blocking activities mediated by the HSV-1 FcγR.
Modification to the Capsid of the Adenovirus Vector That Enhances Dendritic Cell Infection and Transgene-Specific Cellular Immune Responses
Authors: Worgall Stefan , Busch Annette , Rivara Michael , Bonnyay David , Leopold Philip L. , Merritt Robert , Hackett Neil R. , Rovelink Peter W. , Bruder Joseph T. , Wickham Thomas J. , Kovesdi Imi , Crystal Ronald G. 
Published: February 2004

ABSTRACTAdenovirus (Ad) gene transfer vectors can be used to transfer and express antigens and function as strong adjuvants and thus are useful platforms for the development of genetic vaccines. Based on the hypothesis that Ad vectors with enhanced infectibility of dendritic cells (DC) may be able to evoke enhanced immune responses against antigens encoded by the vector in vivo, the present study analyzes the vaccine potential of an Ad vector expressing β-galactosidase as a model antigen and genetically modified with RGD on the fiber knob [AdZ.F(RGD)] to more selectively infect DC and consequently enhance immunity against the β-galactosidase antigen. Infection of murine DC in vitro with AdZ.F(RGD) showed an eightfold-increased transgene expression following infection compared to AdZ (also expressing β-galactosidase, but with a wild-type capsid). Binding, cellular uptake, and trafficking in DC were also increased with AdZ.F(RGD) compared to AdZ. To determine whether AdZ.F(RGD) could evoke enhanced immune responses to β-galactosidase in vivo, C57BL/6 mice were immunized with AdZ.F(RGD) or AdZ subcutaneously via the footpad. Humoral responses with both vectors were comparable, with similar anti-β-galactosidase antibody levels following vector administration. However, cellular responses to β-galactosidase were significantly enhanced, with the frequency of CD4+as well as the CD8+β-galactosidase-specific gamma interferon response in cells isolated from the draining lymph nodes increased following immunization with AdZ.F(RGD) compared to Ad.Z (P< 0.01). Importantly, this enhanced cellular immune response of the AdZ.F(RGD) vector was sufficient to evoke enhanced inhibition of the growth of preexisting tumors expressing β-galactosidase: BALB/c mice implanted with the CT26 syngeneic β-galactosidase-expressing colon carcinoma cell line and subsequently immunized with AdZ.F(RGD) showed decreased tumor growth and improved survival compared to mice immunized with AdZ. These data demonstrate that addition of an RGD motif to the Ad fiber knob increases the infectibility of DC and leads to enhanced cellular immune responses to the Ad-transferred transgene, suggesting that the RGD capsid modification may be useful in developing Ad-based vaccines.
Extraepitopic Compensatory Substitutions Partially Restore Fitness to Simian Immunodeficiency Virus Variants That Escape from an Immunodominant Cytotoxic-T-Lymphocyte Response
Authors: Friedrich Thomas C. , Frye Christopher A. , Yant Levi J. , O'Connor David H. , Kriewaldt Nancy A. , Benson Meghan , Vojnov Lara , Dodds Elizabeth J. , Cullen Candice , Rudersdorf Richard , Hughes Austin L. , Wilson Nancy , Watkins David I. 
Published: February 2004

ABSTRACT

Selection for escape mutant immunodeficiency viruses by cytotoxic T lymphocytes (CTL) has been well characterized and may be associated with disease progression. CTL epitopes accrue escape mutations at different rates in vivo. Interestingly, certain high-frequency CTL do not select for escape until the chronic phase of infection. Here we show that mutations conferring escape from immunodominant CTL directed against an epitope in the viral Gag protein are strongly associated with extraepitopic mutations in
gag
in vivo. The extraepitopic mutations partially restore in vitro replicative fitness of viruses bearing the escape mutations. Constraints on epitope sequences may therefore play a role in determining the rate of escape from CTL responses in vivo.
Inflammatory Cytokines Inhibit Kaposi's Sarcoma-Associated Herpesvirus Lytic Gene Transcription in In Vitro-Infected Endothelial Cells
Authors: Milligan Steven , Robinson Mairi , O'Donnell Elizabeth , Blackbourn David J. 
Published: February 2004

ABSTRACTThe response of Kaposi's sarcoma (KS)-associated herpesvirus (KSHV) to inflammatory cytokine treatment of experimentally infected endothelial cells was investigated. The cytokines inhibited spontaneous KSHV lytic gene expression but not the level of infection. The data suggest that if inflammatory cytokines present in KS lesions contribute to KSHV pathogenesis, they do so in part by promoting latent KSHV infection of the endothelial cells.
Specific Interaction of Feline Immunodeficiency Virus Surface Glycoprotein with Human DC-SIGN
Authors: de Parseval Aymeric , Su Stephen V. , Elder John H. , Lee Benhur 
Published: February 2004

ABSTRACTDC-SIGN, a specific C-type lectin expressed on dendritic cells, binds and transmits multiple strains of primate immunodeficiency viruses to susceptible cells. Here, we report that human DC-SIGN also captures feline immunodeficiency virus via high-affinity (1 nM), Ca2+-dependent,d-mannose-inhibited binding to the major envelope glycoprotein, gp95.
Human Immunodeficiency Virus Type 1 Escapes from RNA Interference-Mediated Inhibition
Authors: Das Atze T. , Brummelkamp Thijn R. , Westerhout Ellen M. , Vink Monique , Madiredjo Mandy , Bernards René , Berkhout Ben 
Published: February 2004

ABSTRACT
Short-term assays have suggested that RNA interference (RNAi) may be a powerful new method for intracellular immunization against human immunodeficiency virus type 1 (HIV-1) infection. However, RNAi has not yet been shown to protect cells against HIV-1 in long-term virus replication assays. We stably introduced vectors expressing small interfering RNAs (siRNAs) directed against the HIV-1 genome into human T cells by retroviral transduction. We report here that an siRNA directed against the viral Nef gene (siRNA-Nef) confers resistance to HIV-1 replication. This block in replication is not absolute, and HIV-1 escape variants that were no longer inhibited by siRNA-Nef appeared after several weeks of culture. These RNAi-resistant viruses contained nucleotide substitutions or deletions in the Nef gene that modified or deleted the siRNA-Nef target sequence. These results demonstrate that efficient inhibition of HIV-1 replication through RNAi is possible in stably transduced cells. Therefore, RNAi could become a realistic gene therapy approach with which to overcome the devastating effect of HIV-1 on the immune system. However, as is known for antiviral drug therapy against HIV-1, antiviral approaches involving RNAi should be used in a combined fashion to prevent the emergence of resistant viruses.
Cryoelectron Microscopy of Mouse Mammary Tumor Virus
Authors: Briggs John A. G. , Watson Barbara E. , Gowen Brent E. , Fuller Stephen D. 
Published: February 2004

ABSTRACT

Cryoelectron microscopy of
Mouse mammary tumor virus
, a
Betaretrovirus
, provided information about glycoprotein structure and core formation. The virions showed the broad range of diameters typical of retroviruses. Betaretroviruses assemble cytoplasmically, so the broad size range cannot reflect the use of the plasma membrane as a platform for assembly.