bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparative Study of Regulation of RTA-Responsive Genes in Kaposi's Sarcoma-Associated Herpesvirus/Human Herpesvirus 8
Authors: Song Moon Jung , Deng Hongyu , Sun Ren 
Published: August 2003

ABSTRACT
Replication and transcription activator (RTA) (also referred to as ORF50), an immediate-early gene product of Kaposi's sarcoma-associated herpesvirus (KSHV)/(human herpesvirus 8), plays a critical role in balancing the viral life cycle between latency and lytic replication. RTA has been shown to act as a strong transcription activator for several downstream genes of KSHV. Direct binding of RTA to DNA is thought to be one of the important mechanisms for transactivation of target genes, while indirect mechanisms are also implicated in RTA transactivation of certain selected genes. This study demonstrated direct binding of the DNA-binding domain of RTA (Rdbd) to a Kaposin (Kpsn) promoter sequence, which is highly homologous to the RTA-responsive element (RRE) of the PAN promoter. We undertook a comparative study of the RREs of PAN RNA, ORF57, vIL-6, and Kpsn to understand how RTA regulates gene expression during lytic replication. Comparing RNA abundance and transcription initiation rates of these RTA target genes in virus-infected cells suggested that the transcription initiation rate of the promoters is a major determinant of viral gene expression, rather than stability of the transcripts. RTA-mediated transactivation of reporters containing each RRE showed that their promoter strengths in a transient-transfection system were comparable to their transcription rates during reactivation. Moreover, our electrophoretic mobility shift assays of each RRE demonstrated that the highly purified Rdbd protein directly bound to the RREs. Based on these results, we conclude that direct binding of RTA to these target sequences contributes to their gene expression to various extents during the lytic life cycle of KSHV.
Identification of Novel Immunodominant CD4+Th1-Type T-Cell Peptide Epitopes from Herpes Simplex Virus Glycoprotein D That Confer Protective Immunity
Authors: BenMohamed Lbachir , Bertrand Georges , McNamara Cory D. , Gras-Masse Helene , Hammer Juergen , Wechsler Steven L. , Nesburn Anthony B. 
Published: August 2003

ABSTRACTThe molecular characterization of the epitope repertoire on herpes simplex virus (HSV) antigens would greatly expand our knowledge of HSV immunity and improve immune interventions against herpesvirus infections. HSV glycoprotein D (gD) is an immunodominant viral coat protein and is considered an excellent vaccine candidate antigen. By using the TEPITOPE prediction algorithm, we have identified and characterized a total of 12 regions within the HSV type 1 (HSV-1) gD bearing potential CD4+T-cell epitopes, each 27 to 34 amino acids in length. Immunogenicity studies of the corresponding medium-sized peptides confirmed all previously known gD epitopes and additionally revealed four new immunodominant regions (gD49-82, gD146-179, gD228-257, and gD332-358), each containing naturally processed epitopes. These epitopes elicited potent T-cell responses in mice of diverse major histocompatibility complex backgrounds. Each of the four new immunodominant peptide epitopes generated strong CD4+Th1 T cells that were biologically active against HSV-1-infected bone marrow-derived dendritic cells. Importantly, immunization of H-2dmice with the four newly identified CD4+Th1 peptide epitopes but not with four CD4+Th2 peptide epitopes induced a robust protective immunity against lethal ocular HSV-1 challenge. These peptide epitopes may prove to be important components of an effective immunoprophylactic strategy against herpes.
The Mason-Pfizer Monkey Virus PPPY and PSAP Motifs Both Contribute to Virus Release
Authors: Gottwein Eva , Bodem Jochen , Müller Barbara , Schmechel Ariane , Zentgraf Hanswalter , Kräusslich Hans-Georg 
Published: August 2003

ABSTRACT
Late (L) domains are required for the efficient release of several groups of enveloped viruses. Three amino acid motifs have been shown to provide L-domain function, namely, PPXY, PT/SAP, or YPDL. The retrovirus Mason-Pfizer monkey virus (MPMV) carries closely spaced PPPY and PSAP motifs. Mutation of the PPPY motif results in a complete loss of virus release. Here, we show that the PSAP motif acts as an additional L domain and promotes the efficient release of MPMV but requires an intact PPPY motif to perform its function. Examination of HeLaP4 cells expressing PSAP mutant virus by electron microscopy revealed mostly late budding structures and chains of viruses accumulating at the cell surface with little free virus. In the case of the PPPY mutant virus, budding appeared to be mostly arrested at an earlier stage before induction of membrane curvature. The cellular protein TSG101, which interacts with the human immunodeficiency virus type 1 (HIV-1) PTAP L domain, was packaged into MPMV in a PSAP-dependent manner. Since TSG101 is crucial for HIV-1 release, this result suggests that the Gag-TSG101 interaction is responsible for the virus release function of the MPMV PSAP motif. Nedd4, which has been shown to interact with viral PPPY motifs, was also detected in MPMV particles, albeit at much lower levels. Consistent with a role of VPS4A in the budding of both PPPY and PTAP motif-containing viruses, the overexpression of ATPase-defective GFP-VPS4A fusion proteins blocked both wild-type and PSAP mutant virus release.
Monkey Rotavirus Binding to α2β1 Integrin Requires the α2 I Domain and Is Facilitated by the Homologous β1 Subunit
Authors: Londrigan Sarah L. , Graham Kate L. , Takada Yoshikazu , Halasz Peter , Coulson Barbara S. 
Published: August 2003

ABSTRACT
Rotaviruses utilize integrins during virus-cell interactions that lead to infection. Cell binding and infection by simian rotavirus SA11 were inhibited by antibodies (Abs) to the inserted (I) domain of the α2 integrin subunit. To determine directly which integrins or other proteins bind rotaviruses, cell surface proteins precipitated by rotaviruses were compared with those precipitated by anti-α2β1 Abs. Two proteins precipitated by SA11 and rhesus rotavirus RRV from MA104 and Caco-2 cells migrated indistinguishably from α2β1 integrin, and SA11 precipitated β1 from α2β1-transfected CHO cells. These viruses specifically precipitated two MA104 cell proteins only, but an additional 160- to 165-kDa protein was precipitated by SA11 from Caco-2 cells. The role of the α2 I domain in rotavirus binding, infection, and growth was examined using CHO cell lines expressing wild-type or mutated human α2 or α2β1. Infectious SA11 and RRV, but not human rotavirus Wa, specifically bound CHO cell-expressed human α2β1 and, to a lesser extent, human α2 combined with hamster β1. Binding was inhibited by anti-α2 I domain monoclonal Abs (MAbs), but not by non-I domain MAbs to α2, and required the presence of the α2 I domain. Amino acid residues 151, 221, and 254 in the metal ion-dependent adhesion site of the α2 I domain that are necessary for type I collagen binding to α2β1 were not essential for rotavirus binding. Rotavirus-α2β1 binding led to increased virus infection and RRV growth. SA11 and RRV require the α2 I domain for binding to α2β1, and their binding to this integrin is distinguishable from that of collagen.
Complementation of a Deletion in the Rubella Virus P150 Nonstructural Protein by the Viral Capsid Protein
Authors: Tzeng Wen-Pin , Frey Teryl K. 
Published: August 2003

ABSTRACT

Rubella virus (RUB) replicons with an in-frame deletion of 507 nucleotides between two
Not
I sites in the P150 nonstructural protein (Δ
Not
I) do not replicate (as detected by expression of a reporter gene encoded by the replicon) but can be amplified by wild-type helper virus (Tzeng et al., Virology
289:
63-73, 2001). Surprisingly, virus with Δ
Not
I was viable, and it was hypothesized that this was due to complementation of the
Not
I deletion by one of the virion structural protein genes. Introduction of the capsid (C) protein gene into Δ
Not
I-containing replicons as an in-frame fusion with a reporter gene or cotransfection with both Δ
Not
I replicons and RUB replicon or plasmid constructs containing the C gene resulted in replication of the Δ
Not
I replicon, confirming the hypothesis that the C gene was the structural protein gene responsible for complementation and demonstrating that complementation could occur either in
cis
or in
trans
. Approximately the 5′ one-third of the C gene was necessary for complementation. Mutations that prevented translation of the C protein while minimally disturbing the C gene sequence abrogated complementation, while synonymous codon mutations that changed the C gene sequence without affecting the amino acid sequence at the 5′ end of the C gene had no effect on complementation, indicating that the C protein, not the C gene RNA, was the moiety responsible for complementation. Complementation occurred at a basic step in the virus replication cycle, because Δ
Not
I replicons failed to accumulate detectable virus-specific RNA.
Pre-S1 Antigen-Dependent Infection of
Tupaia
Hepatocyte Cultures with Human Hepatitis B Virus
Authors: Glebe Dieter , Aliakbari Mehriar , Krass Peter , Knoop Eva V. , Valerius Klaus P. , Gerlich Wolfram H. 
Published: August 2003

ABSTRACT

The susceptibility of the tree shrew
Tupaia belangeri
to human hepatitis B virus (HBV) has been demonstrated both in vivo and in vitro. In this study, we show that purified HBV infects primary
T. belangeri
hepatocyte cultures in a very specific manner, as detected by HBV covalently closed circular DNA, mRNA, HBV e antigen, and HBsAg production. A monoclonal antibody (MAb), MA18/7, directed against the pre-S1 domain of the large HBs protein, which has been shown to neutralize infectivity of HBV for primary human hepatocytes, also blocked infection of primary
Tupaia
hepatocytes. MAbs against the pre-S2 domain of HBs inhibited infection only partially, whereas an S MAb and polyvalent anti-HBs antibodies neutralized infection completely. Thus, both pre-S1 and S antigens are necessary for infection in the tupaia. Using subviral particles, >70% of primary
Tupaia
hepatocytes are capable of specific binding of pre-S1-rich HBsAg, showing localization in distinct membrane areas. The data show that the early steps of HBV infection in
Tupaia
hepatocyte cultures are comparable to those in the human system.
Newcastle Disease Virus V Protein Is a Determinant of Host Range Restriction
Authors: Park Man-Seong , García-Sastre Adolfo , Cros Jerome F. , Basler Christopher F. , Palese Peter 
Published: August 2003

ABSTRACT
It has been demonstrated that the V protein of Newcastle disease virus (NDV) functions as an alpha/beta interferon (IFN-α/β) antagonist (M. S. Park, M. L. Shaw, J. Muñoz-Jordan, J. F. Cros, T. Nakaya, N. Bouvier, P. Palese, A. García-Sastre, and C. F. Basler, J. Virol. 77:1501-1511, 2003). We now show that the NDV V protein plays an important role in host range restriction. In order to study V functions in vivo, recombinant NDV (rNDV) mutants, defective in the expression of the V protein, were generated. These rNDV mutants grow poorly in both embryonated chicken eggs and chicken embryo fibroblasts (CEFs) compared to the wild-type (wt) rNDV. However, insertion of the NS1 gene of influenza virus A/PR8/34 into the NDV V(−) genome [rNDV V(−)/NS1] restores impaired growth to wt levels in embryonated chicken eggs and CEFs. These data indicate that for viruses infecting avian cells, the NDV V protein and the influenza NS1 protein are functionally interchangeable, even though there are no sequence similarities between the two proteins. Interestingly, in human cells, the titer of wt rNDV is 10 times lower than that of rNDV V(−)/NS1. Correspondingly, the level of IFN secreted by human cells infected with wt rNDV is much higher than that secreted by cells infected with the NS1-expressing rNDV. This suggests that the IFN antagonist activity of the NDV V protein is species specific. Finally, the NDV V protein plays an important role in preventing apoptosis in a species-specific manner. The rNDV defective in V induces apoptotic cell death more rapidly in CEFs than does wt rNDV. Taken together, these data suggest that the host range of NDV is limited by the ability of its V protein to efficiently prevent innate host defenses, such as the IFN response and apoptosis.
Latent Herpes Simplex Virus Infection of Sensory Neurons Alters Neuronal Gene Expression
Authors: Kramer Martha F. , Cook W. James , Roth Frederick P. , Zhu Jia , Holman Holly , Knipe David M. , Coen Donald M. 
Published: August 2003

ABSTRACTThe persistence of herpes simplex virus (HSV) and the diseases that it causes in the human population can be attributed to the maintenance of a latent infection within neurons in sensory ganglia. Little is known about the effects of latent infection on the host neuron. We have addressed the question of whether latent HSV infection affects neuronal gene expression by using microarray transcript profiling of host gene expression in ganglia from latently infected versus mock-infected mouse trigeminal ganglia.33P-labeled cDNA probes from pooled ganglia harvested at 30 days postinfection or post-mock infection were hybridized to nylon arrays printed with 2,556 mouse genes. Signal intensities were acquired by phosphorimager. Mean intensities (n= 4 replicates in each of three independent experiments) of signals from mock-infected versus latently infected ganglia were compared by using a variant of Student'sttest. We identified significant changes in the expression of mouse neuronal genes, including several with roles in gene expression, such as the Clk2 gene, and neurotransmission, such as genes encoding potassium voltage-gated channels and a muscarinic acetylcholine receptor. We confirmed the neuronal localization of some of these transcripts by using in situ hybridization. To validate the microarray results, we performed real-time reverse transcriptase PCR analyses for a selection of the genes. These studies demonstrate that latent HSV infection can alter neuronal gene expression and might provide a new mechanism for how persistent viral infection can cause chronic disease.
Specific Association of Glycoprotein B with Lipid Rafts during Herpes Simplex Virus Entry
Authors: Bender Florent C. , Whitbeck J. Charles , Ponce de Leon Manuel , Lou Huan , Eisenberg Roselyn J. , Cohen Gary H. 
Published: August 2003

ABSTRACTHerpes simplex virus (HSV) entry requires the interaction of glycoprotein D (gD) with a cellular receptor such as herpesvirus entry mediator (HVEM or HveA) or nectin-1 (HveC). However, the fusion mechanism is still not understood. Since cholesterol-enriched cell membrane lipid rafts are involved in the entry of other enveloped viruses such as human immunodeficiency virus and Ebola virus, we tested whether HSV entry proceeds similarly. Vero cells and cells expressing either HVEM or nectin-1 were treated with cholesterol-sequestering drugs such as methyl-β-cyclodextrin or nystatin and then exposed to virus. In all cases, virus entry was inhibited in a dose-dependent manner, and the inhibitory effect was fully reversible by replenishment of cholesterol. To examine the association of HVEM and nectin-1 with lipid rafts, we analyzed whether they partitioned into nonionic detergent-insoluble glycolipid-enriched membranes (DIG). There was no constitutive association of either receptor with DIG. Binding of soluble gD or virus to cells did not result in association of nectin-1 with the raft-containing fractions. However, during infection, a fraction of gB but not gC, gD, or gH associated with DIG. Similarly, when cells were incubated with truncated soluble glycoproteins, soluble gB but not gC was found associated with DIG. Together, these data favor a model in which HSV uses gB to rapidly mobilize lipid rafts that may serve as a platform for entry and cell signaling. It also suggests that gB may interact with a cellular molecule associated with lipid rafts.
Structural and Phylogenetic Analysis of Adenovirus Hexons by Use of High-Resolution X-Ray Crystallographic, Molecular Modeling, and Sequence-Based Methods
Authors: Rux John J. , Kuser Paula R. , Burnett Roger M. 
Published: August 2003

ABSTRACTA major impediment to the use of adenovirus as a gene therapy vector and for vaccine applications is the host immune response to adenovirus hexon—the major protein component of the icosahedral capsid. A solution may lie in novel vectors with modified or chimeric hexons designed to evade the immune response. To facilitate this approach, we have distinguished the portion of hexon that all serotypes have in common from the hypervariable regions that are responsible for capsid diversity and type-specific immunogenicity. The common hexon core—conserved because it forms the viral capsid—sets boundaries to the regions where modifications can be made to produce nonnative hexons. The core has been defined from the large and diverse set of known hexon sequences by an accurate alignment based on the newly refined crystal structures of human adenovirus types 2 (Ad2) and Ad5 hexon. Comparison of the two hexon models, which are the most accurate so far, reveals that over 90% of the residues in each have three-dimensional positions that closely match. Structures for more distant hexons were predicted by building molecular models of human Ad4, chimpanzee adenovirus (AdC68), and fowl adenovirus 1 (FAV1 or CELO). The five structures were then used to guide the alignment of the 40 full-length (>900 residues) hexon sequences in public databases. Distance- and parsimony-based phylogenetic trees are consistent and reveal evolutionary relationships between adenovirus types that parallel those of their animal hosts. The combination of crystallography, molecular modeling, and phylogenetic analysis defines a conserved molecular core that can serve as the armature for the directed design of novel hexons.
Phylogenetic and Evolutionary Relationships among Torovirus Field Variants: Evidence for Multiple Intertypic Recombination Events
Authors: Smits S. L. , Lavazza A. , Matiz K. , Horzinek M. C. , Koopmans M. P. , de Groot R. J. 
Published: August 2003

ABSTRACT

Toroviruses (family
Coronaviridae
, order
Nidovirales
) are enveloped, positive-stranded RNA viruses that have been implicated in enteric disease in cattle and possibly in humans. Despite their potential veterinary and clinical relevance, little is known about torovirus epidemiology and molecular genetics. Here, we present the first study into the diversity among toroviruses currently present in European swine and cattle herds. Comparative sequence analysis was performed focusing on the genes for the structural proteins S, M, HE, and N, with fecal specimens serving as sources of viral RNA. Sequence data published for animal and human torovirus variants were included. Four genotypes, displaying 30 to 40% divergence, were readily distinguished, exemplified by bovine torovirus (BToV) Breda, porcine torovirus (PToV) Markelo, equine torovirus Berne, and the putative human torovirus. The ungulate toroviruses apparently display host species preference. In phylogenetic analyses, all PToV variants clustered, while the recent European BToVs mostly resembled the New World BToV variant Breda, identified 19 years ago. However, we found ample evidence for recurring intertypic recombination. All newly characterized BToV variants seem to have arisen from a genetic exchange, during which the 3′ end of the HE gene, the N gene, and the 3′ nontranslated region of a Breda virus-like parent had been swapped for those of PToV. Moreover, some PToV and BToV variants carried chimeric HE genes, which apparently resulted from recombination events involving hitherto unknown toroviruses. From these observations, the existence of two additional torovirus genotypes can be inferred. Toroviruses may be even more promiscuous than their closest relatives, the coronaviruses and arteriviruses.
Epidemiology, Genetic Diversity, and Evolution of Endemic Feline Immunodeficiency Virus in a Population of Wild Cougars
Authors: Biek Roman , Rodrigo Allen G. , Holley David , Drummond Alexei , Anderson Charles R. , Ross Howard A. , Poss Mary 
Published: August 2003

ABSTRACT

Within the large body of research on retroviruses, the distribution and evolution of endemic retroviruses in natural host populations have so far received little attention. In this study, the epidemiology, genetic diversity, and molecular evolution of feline immunodeficiency virus specific to cougars (FIVpco) was examined using blood samples collected over several years from a free-ranging cougar population in the western United States. The virus prevalence was 58% in this population (
n
= 52) and increased significantly with host age. Based on phylogenetic analysis of fragments of envelope (
env
) and polymerase (
pol
) genes, two genetically distinct lineages of FIVpco were found to cooccur in the population but not in the same individuals. Within each of the virus lineages, geographically nearby isolates formed monophyletic clusters of closely related viruses. Sequence diversity for
env
within a host rarely exceeded 1%, and the evolution of this gene was dominated by purifying selection. For both
pol
and
env
, our data indicate mean rates of molecular evolution of 1 to 3% per 10 years. These results support the premise that FIVpco is well adapted to its cougar host and provide a basis for comparing lentivirus evolution in endemic and epidemic infections in natural hosts.