bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of the DNA-Binding Domain of the Bovine Papillomavirus Replication Initiator E1
Authors: Chen Grace , Stenlund Arne 
Published: December 2019

ABSTRACT

The bovine papillomavirus replication initiator protein E1 is an origin of replication (
ori
)-binding protein absolutely required for viral DNA replication. In the presence of the viral transcription factor E2, E1 binds to the
ori
and initiates DNA replication. To understand how the E1 initiator recognizes the
ori
and how E2 assists in this process, we have expressed and purified a 166-amino-acid fragment which corresponds to the minimal E1 DNA-binding domain (DBD). DNA binding studies using this protein demonstrate that the E1 DBD can bind to the palindromic E1 binding site in several forms but that binding of two monomers, each recognizing one half-site of the E1 palindrome, is the predominant form. This is reminiscent of the binding of the T-antigen DBD to the SV40
ori
, and interestingly, the arrangement of E1 binding sites shows striking similarities to the arrangement of T-antigen binding sites in the SV40
ori
even though the recognition sequences are unrelated. The E1 DBD is capable of interacting cooperatively with E2; however, the E2 DBD and not the E2 activation domain mediates this interaction. Furthermore, the E2 DBD stimulates binding of two monomers of the E1 DBD to the
ori
by binding cooperatively with one E1 monomer. Finally, we show that our results concerning the DNA-binding properties of the E1 DBD can be extended to full-length E1.
Role of Actin Microfilaments in Black Creek Canal Virus Morphogenesis
Authors: Ravkov Eugene V. , Nichol Stuart T. , Peters Clarence J. , Compans Richard W. 
Published: December 2019

ABSTRACT
We have investigated the involvement of cytoskeletal proteins in the morphogenesis of Black Creek Canal virus (BCCV), a New World hantavirus. Immunofluorescent staining of BCCV-infected cells revealed a filamentous pattern of virus antigen, the appearance of which was sensitive to treatment with cytochalasin D, an actin microfilament-depolymerizing drug. Double immunofluorescence staining of BCCV-infected Vero cells with anti-BCCV nucleocapsid (N) monoclonal antibody and phalloidin revealed a colocalization of the BCCV N protein with actin microfilaments. A similar, though less prominent, filamentous pattern was observed in BHK21 cells transiently expressing the BCCV N protein alone but not in cells expressing the BCCV G1 and G2 glycoproteins. Moreover, the association of the N protein with actin microfilaments was confirmed by coimmunoprecipitation with β-actin-specific antibody. Treatment of the BCCV-infected Vero cells at 3 days postinfection with cytochalasin D decreased the yield of released BCCV by 94% relative to the yield from untreated cells. Pretreatment of Vero cells with cytochalasin D prior to and during BCCV adsorption and entry had no effect on the outcome of virus production. These results indicate that actin filaments may play an important role in hantavirus assembly and/or release.
Priming with Secreted Glycoprotein G of Respiratory Syncytial Virus (RSV) Augments Interleukin-5 Production and Tissue Eosinophilia after RSV Challenge
Authors: Johnson Teresa R. , Johnson Joyce E. , Roberts Sharon R. , Wertz Gail W. , Parker Robert A. , Graham Barney S. 
Published: December 2019

ABSTRACTThe respiratory syncytial virus (RSV) G glycoprotein promotes differentiation of type 2 CD4+T lymphocytes and induces an eosinophilic response in lungs of RSV-infected mice. A unique feature of G is that a second initiation codon in the transmembrane region of the glycoprotein results in secretion of soluble protein from infected cells. Recombinant vaccinia viruses that express wild-type G (vvWT G), only secreted G (vvM48), or only membrane-anchored G (vvM48I) were used to define the influence of G priming on immunopathogenesis. Mice immunized with vvM48 had more severe illness following RSV challenge than did mice primed with vvWT G or vvM48I. Coadministration of purified G during priming with the construct expressing membrane-anchored G shifted immune responses following RSV challenge to a more Th2-like response. This was characterized by increased interleukin-5 in lung supernatants and an increase in G-specific immunoglobulin G1 antibodies. Eosinophils were present in the infiltrate of all mice primed with G-containing vectors but were greatest in mice primed with regimens including secreted G. These data suggest the form of G protein available for initial antigen processing and presentation is an important factor in promoting Th2-like immune responses, including the induction of lung eosinophilia. The ability of RSV to secrete G protein may therefore represent a viral strategy for immunomodulation and be a key determinant of disease pathogenesis.
Cytotoxic T-Lymphocyte Target Proteins and Their Major Histocompatibility Complex Class I Restriction in Response to Adenovirus Vectors Delivered to Mouse Liver
Authors: Jooss Karin , Ertl Hildegund C. J. , Wilson James M. 
Published: December 2019

ABSTRACTThe activation of cytotoxic T lymphocytes (CTLs) to cells infected with adenovirus vectors contributes to problems of inflammation and transient gene expression that attend their use in gene therapy. The goal of this study was to identify in a murine model of liver gene therapy the proteins that provide targets to CTLs and to characterize the major histocompatibility complex (MHC) class I restricting elements. Mice of different MHC haplotypes were infected with an E1-deleted adenovirus expressing human alkaline phosphatase (ALP) or β-galactosidase as a reporter protein, and splenocytes were harvested for in vitro CTL assays to aid in the characterization of CTL epitopes. A library of vaccinia viruses was created to express individual viral open reading frames, as well as the ALP andlacZtransgenes. The MHC haplotype had a dramatic impact on the distribution of CTL targets: in C57BL/6 mice, the hexon protein presented by both H-2Kband H2Dbwas dominant, and in C3H mice, H-2Dk-restricted presentation of ALP was dominant. Adoptive transfer of CTLs specific for various adenovirus proteins or transgene products into either Rag-I or C3H-scid mice infected previously with an E1-deleted adenovirus verified the in vivo relevance of the adenovirus-specific CTL targets identified in vitro. The results of these experiments illustrate the impact of lr gene control on the response to gene therapy with adenovirus vectors and suggest that the efficacy of therapy with adenovirus vectors may exhibit considerable heterogeneity when applied in human populations.
Ubiquitin Is Covalently Attached to the p6
Gag
Proteins of Human Immunodeficiency Virus Type 1 and Simian Immunodeficiency Virus and to the p12
Gag
Protein of Moloney Murine Leukemia Virus
Authors: Ott David E. , Coren Lori V. , Copeland Terry D. , Kane Bradley P. , Johnson Donald G. , Sowder Raymond C. , Yoshinaka Yoshiyuki , Oroszlan Stephen , Arthur Larry O. , Henderson Louis E. 
Published: December 2019

ABSTRACT

Host proteins are incorporated into retroviral virions during assembly and budding. We have examined three retroviruses, human immunodeficiency virus type 1 (HIV-1), simian immunodeficiency virus (SIV), and Moloney murine leukemia virus (Mo-MuLV), for the presence of ubiquitin inside each of these virions. After a protease treatment to remove exterior viral as well as contaminating cellular proteins, the proteins remaining inside the virion were analyzed. The results presented here show that all three virions incorporate ubiquitin molecules at approximately 10% of the level of Gag found in virions. In addition to free ubiquitin, covalent ubiquitin-Gag complexes were detected, isolated, and characterized from all three viruses. Our immunoblot and protein sequencing results on treated virions showed that approximately 2% of either HIV-1 or SIV p6
Gag
was covalently attached to a single ubiquitin molecule inside the respective virions and that approximately 2 to 5% of the p12
Gag
in Mo-MuLV virions was monoubiquitinated. These results show that ubiquitination of Gag is conserved among these retroviruses and occurs in the p6
Gag
portion of the Gag polyprotein, a region that is likely to be involved in assembly and budding.
Adenovirus Type 5 E4 Open Reading Frame 4 Protein Induces Apoptosis in Transformed Cells
Authors: Shtrichman Ronit , Kleinberger Tamar 
Published: December 2019

ABSTRACT

Adenovirus type 5 E4 open reading frame 4 (E4orf4) protein has been previously shown to counteract transactivation of the
junB
and c-
fos
genes by cyclic AMP plus E1A protein and to interact with protein phosphatase 2A (PP2A). Here, we show that the wild-type E4orf4 protein induces apoptosis in the E1A-expressing 293 cells, in NIH 3T3 cells transformed with v-Ras, and in the lung carcinoma cell line H1299. The induction of apoptosis is not accompanied by enhanced levels of p53 in 293 cells and occurs in the absence of p53 in H1299 cells, indicating involvement of a p53-independent pathway. A mutant E4orf4 protein that had lost the ability to induce apoptosis also lost its ability to bind PP2A. We suggest that E4orf4 antagonizes continuous signals to proliferate, like those given by E1A or v-Ras, and that the conflicting signals lead to the induction of cell death.
Viral Coat Protein Peptides with Limited Sequence Homology Bind Similar Domains of Alfalfa Mosaic Virus and Tobacco Streak Virus RNAs
Authors: Swanson Maud M. , Ansel-McKinney Patricia , Houser-Scott Felicia , Yusibov Vidadi , Loesch-Fries L. Sue , Gehrke Lee 
Published: December 2019

ABSTRACT
An unusual and distinguishing feature of alfalfa mosaic virus (AMV) and ilarviruses such as tobacco streak virus (TSV) is that the viral coat protein is required to activate the early stages of viral RNA replication, a phenomenon known as genome activation. AMV-TSV coat protein homology is limited; however, they are functionally interchangeable in activating virus replication. For example, TSV coat protein will activate AMV RNA replication and vice versa. Although AMV and TSV coat proteins have little obvious amino acid homology, we recently reported that they share an N-terminal RNA binding consensus sequence (Ansel-McKinney et al., EMBO J. 15:5077–5084, 1996). Here, we biochemically compare the binding of chemically synthesized peptides that include the consensus RNA binding sequence and lysine-rich (AMV) or arginine-rich (TSV) environment to 3′-terminal TSV and AMV RNA fragments. The arginine-rich TSV coat protein peptide binds viral RNA with lower affinity than the lysine-rich AMV coat protein peptides; however, the ribose moieties protected from hydroxyl radical attack by the two different peptides are localized in the same area of the predicted RNA structures. When included in an infectious inoculum, both AMV and TSV 3′-terminal RNA fragments inhibited AMV RNA replication, while variant RNAs unable to bind coat protein did not affect replication significantly. The data suggest that RNA binding and genome activation functions may reside in the consensus RNA binding sequence that is apparently unique to AMV and ilarvirus coat proteins.
Synergistic Neutralization of Simian-Human Immunodeficiency Virus SHIV-vpu+by Triple and Quadruple Combinations of Human Monoclonal Antibodies and High-Titer Anti-Human Immunodeficiency Virus Type 1 Immunoglobulins
Authors: Li An , Katinger Hermann , Posner Marshall R. , Cavacini Lisa , Zolla-Pazner Susan , Gorny Miroslaw K. , Sodroski Joseph , Chou Ting-Chao , Baba Timothy W. , Ruprecht Ruth M. 
Published: December 2019

ABSTRACTWe have tested triple and quadruple combinations of human monoclonal antibodies (MAbs), which are directed against various epitopes on human immunodeficiency virus type 1 (HIV-1) envelope glycoproteins, and a high-titer anti-HIV-1 human immunoglobulin (HIVIG) preparation for their abilities to neutralize a chimeric simian-human immunodeficiency virus (SHIV-vpu+). This virus encodes the HIV-1 strain IIIBenv,tat,rev, andvpugenes. The quantitative nature of the Chou-Talalay method (Adv. Enzyme Regul. 22:27–55, 1984) allows ranking of various combinations under identical experimental conditions. Of all triple combinations tested, the most potent neutralization was seen with MAbs 694/98D plus 2F5 plus 2G12 (directed against domains on V3, gp41, and gp120, respectively) as measured by the total MAb concentration required to reach 90% neutralization (90% effective concentration [EC90], 2.0 μg/ml). All triple combinations involving MAbs and/or HIVIG that were tested yielded synergy with combination index values of <1; the dose reduction indices (DRIs) ranged from 3.1 to 26.2 at 90% neutralization. When four MAbs (the previous three plus MAb F105, directed against the CD4 binding site) were combined, higher neutralization potency (EC90, 1.8 μg/ml) and a higher degree of synergy compared to any triple combination were seen. The mean DRIs of the quadruple combination were approximately twice that of the most synergistic triple combination. We conclude that human MAbs targeting different HIV-1 envelope glycoprotein epitopes exhibit strong synergy when used in combination, a fact that could be exploited clinically for passive immunoprophylaxis against HIV-1.
Persistence and Expression of the Herpes Simplex Virus Genome in the Absence of Immediate-Early Proteins
Authors: Samaniego Lorna A. , Neiderhiser Lisa , DeLuca Neal A. 
Published: December 2019

ABSTRACT

The immediate-early (IE) proteins of herpes simplex virus (HSV) function on input genomes and affect many aspects of host cell metabolism to ensure the efficient expression and regulation of the remainder of the genome and, subsequently, the production of progeny virions. Due to the many and varied effects of IE proteins on host cell metabolism, their expression is not conducive to normal cell function and viability. This presents a major impediment to the use of HSV as a vector system. In this study, we describe a series of ICP4 mutants that are defective in different subsets of the remaining IE genes. One mutant,
d
109, does not express any of the IE proteins and carries a green fluorescent protein (GFP) transgene under the control of the human cytomegalovirus IE promoter (HCMVIEp).
d
109 was nontoxic to Vero and human embryonic lung (HEL) cells at all multiplicities of infection tested and was capable of establishing persistent infections in both of these cell types. Paradoxically, the genetic manipulations that were required to eliminate toxicity and allow the genome to persist in cells for long periods of time also dramatically lowered the level of transgene expression. Efficient expression of the HCMVIEp-GFP transgene in the absence of ICP4 was dependent on the ICP0 protein. In
d
109-infected cells, the level of transgene expression was very low in most cells but abundant in a small subpopulation of cells. However, expression of the transgene could be induced in cells containing quiescent
d
109 genomes weeks after the initial infection, demonstrating the functionality of the persisting genomes.
Role of the β-Chemokine Receptors CCR3 and CCR5 in Human Immunodeficiency Virus Type 1 Infection of Monocytes and Microglia
Authors: Ghorpade Anuja , Xia Meng Qi , Hyman Bradley T. , Persidsky Yuri , Nukuna Adeline , Bock Paul , Che Myhanh , Limoges Jenae , Gendelman Howard E. , Mackay Charles R. 
Published: December 2019

ABSTRACTHuman immunodeficiency virus type 1 (HIV-1) infection in mononuclear phagocyte lineage cells (monocytes, macrophages, and microglia) is a critical component in the pathogenesis of viral infection. Viral replication in macrophages serves as a reservoir, a site of dissemination, and an instigator for neurological sequelae during HIV-1 disease. Recent studies demonstrated that chemokine receptors are necessary coreceptors for HIV-1 entry which determine viral tropism for different cell types. To investigate the relative contribution of the β-chemokine receptors CCR3 and CCR5 to viral infection of mononuclear phagocytes we utilized a panel of macrophage-tropic HIV-1 strains (from blood and brain tissue) to infect highly purified populations of monocytes and microglia. Antibodies to CD4 (OKT4A) abrogated HIV-1 infection. The β chemokines and antibodies to CCR3 failed to affect viral infection of both macrophage cell types. Antibodies to CCR5 (3A9) prevented monocyte infection but only slowed HIV replication in microglia. Thus, CCR5, not CCR3, is an essential receptor for HIV-1 infection of monocytes. Microglia express both CCR5 and CCR3, but antibodies to them fail to inhibit viral entry, suggesting the presence of other chemokine receptors for infection of these cells. These studies demonstrate the importance of mononuclear phagocyte heterogeneity in establishing HIV-1 infection and persistence.
Rotavirus 2/6 Viruslike Particles Administered Intranasally with Cholera Toxin,
Escherichia coli
Heat-Labile Toxin (LT), and LT-R192G Induce Protection from Rotavirus Challenge
Authors: O’Neal Christine M. , Clements John D. , Estes Mary K. , Conner Margaret E. 
Published: December 2019

ABSTRACT

We have shown that rotavirus 2/6 viruslike particles composed of proteins VP2 and VP6 (2/6-VLPs) administered to mice intranasally with cholera toxin (CT) induced protection from rotavirus challenge, as measured by virus shedding. Since it is unclear if CT will be approved for human use, we evaluated the adjuvanticity of
Escherichia coli
heat-labile toxin (LT) and LT-R192G. Mice were inoculated intranasally with 10 μg of 2/6-VLPs combined with CT, LT, or LT-R192G. All three adjuvants induced equivalent geometric mean titers of rotavirus-specific serum antibody and intestinal immunoglobulin G (IgG). Mice inoculated with 2/6-VLPs with LT produced significantly higher titers of intestinal IgA than mice given CT as the adjuvant. All mice inoculated with 2/6-VLPs mixed with LT and LT-R192G were totally protected (100%) from rotavirus challenge, while mice inoculated with 2/6-VLPs mixed with CT showed a mean 91% protection from challenge. The availability of a safe, effective mucosal adjuvant such as LT-R192G will increase the practicality of administering recombinant vaccines mucosally.
Virological and Molecular Demonstration of Human Immunodeficiency Virus Type 2 Vertical Transmission
Authors: Cavaco-Silva Patricia , Taveira Nuno C. , Rosado Lino , Lourenço Maria H. , Moniz-Pereira José , Douglas Nigel W. , Daniels Rod S. , Santos-Ferreira Maria O. 
Published: December 2019

ABSTRACT

To demonstrate that human immunodeficiency virus type 2 (HIV-2) mother-to-child transmission exists, HIV-2 isolates were obtained from both an asymptomatic mother (HIV-2 strain ARM), and her child (HIV-2 strain SAR), who had a diagnosis of AIDS. To determine their biological phenotype, primary isolates were used to infect various primary mononuclear cells and cell lines. HIV-2 ARM replicates in primary cells and Jurkat-
tat
, while HIV-2 SAR infects these cells plus SupT1, which led us to classify HIV-2 ARM as a slow/low virus and HIV-2 SAR as having an intermediate (slow/low-3) phenotype. Molecular analysis of the
env
region corresponding to gp125 was performed. Viral DNA was cloned, sequenced, and used to construct phylogenetic trees. The DNA sequence analysis demonstrated an overall nucleotide diversity of 7.6%. The results present evidence that the child’s strain is more virulent than the mother’s strain, which is in agreement with the immunodeficiency of the child. The phylogenetic trees that were constructed demonstrate that the two isolates cluster together, being closer to each other than to any other isolate described until now.
The Entire Nucleotide Sequence of Friend-Related and Paralysis-Inducing PVC-441 Murine Leukemia Virus (MuLV) and Its Comparison with Those of PVC-211 MuLV and Friend MuLV
Authors: Tanaka Atsushi , Oka Kiyomasa , Tanaka Keiji , Jinno Atsushi , Ruscetti Sandra K. , Kai Kazushige 
Published: December 2019

ABSTRACT

PVC-441 murine leukemia virus (MuLV) is a member of the PVC group of Friend MuLV (F-MuLV)-derived neuropathogenic retroviruses. In order to determine the molecular basis for the difference in neuropathogenicity between PVC-441 and the previously characterized PVC-211 MuLVs, the entire nucleotide sequence of PVC-441 MuLV was determined and compared with those of PVC-211 and F-MuLV. The results suggest that PVC-441 and PVC-211 MuLVs were formed as a result of random mutations of F-MuLV and developed differently. The distinct pathogenicities of PVC-441 and PVC-211 MuLVs were maintained in the viruses regenerated from their molecular clones, and the sequences responsible for the pathological differences observed can be localized to the
env
gene. The amino acid sequence of PVC-441 deduced from its nucleotide sequence revealed a number of differences from PVC-211, the most striking of which was a difference at position 129 of the SU proteins in the two viruses. Host range studies with a brain capillary endothelial cell line (RTEC-6) and Chinese hamster ovary cells (CHO-K1) revealed that PVC-441, like PVC-211, could infect these cells but its efficiency of infection was lower than that of PVC-211. These results may account for the difference in neuropathogenicity between PVC-441 and PVC-211.
The U3 Promoter and the
nef
Gene of Simian Immunodeficiency Virus (SIV) smmPBj1.9 Do Not Confer Acute Pathogenicity upon SIVagm
Authors: Wagener Stefan , Dittmar Matthias T. , Beer Brigitte , König Renate , Plesker Roland , Norley Stephen , Kurth Reinhard , Cichutek Klaus 
Published: December 2019

ABSTRACT

Two chimeric proviruses comprising the U3 promoter and the
nef
gene of simian immunodeficiency virus (SIV) smmPBj1.9 in addition to other genomic regions of SIVagm3mc from African green monkeys (
Cercopithecus aethiops
) were constructed. The derived chimeric viruses (SIVagm3mc/SIVsmmPBj1.9) were both able to replicate in nonstimulated peripheral blood leukocytes from pig-tailed macaques (
Macaca nemestrina
), a biological property often correlated with acute pathogenicity. However, only one of the chimeric viruses was acutely pathogenic, inducing a rapid depletion of the peripheral CD4
+
T cells in two infected pig-tailed macaques within 10 days after infection in a manner similar to infection with SIVsmmPBj1.9 itself. The other chimeric virus actively replicated during the first 8 weeks after experimental infection of two pig-tailed macaques but induced neither acute disease nor CD4
+
T-cell depletion for 113 weeks after infection. Thus, the U3 promoter and the
nef
gene of SIVsmmPBj1.9 alone appear to be insufficient to confer acute pathogenicity to SIVagm3mc.
Cleavage of Human Immunodeficiency Virus Type 1 Proteinase from the N-Terminally Adjacent p6* Protein Is Essential for Efficient Gag Polyprotein Processing and Viral Infectivity
Authors: Tessmer Uwe , Kräusslich Hans-Georg 
Published: December 2019

ABSTRACT
Maturation of infectious human immunodeficiency virus (HIV) particles requires proteolytic cleavage of the structural polyproteins by the viral proteinase (PR), which is itself encoded as part of the Gag-Pol polyprotein. Expression of truncated PR-containing sequences in heterologous systems has mostly led to the autocatalytic release of an 11-kDa species of PR which is capable of processing all known cleavage sites on the viral precursor proteins. Relatively little is known about cleavages within the nascent virus particle, on the other hand, and controversial results concerning the active PR species inside the virion and the relative activities of extended PR species have been reported. Here, we report that HIV type 1 (HIV-1) particles of four different strains obtained from different cell lines contain an 11-kDa PR, with no extended PR proteins detectable. Furthermore, mutation of the N-terminal PR cleavage site leading to production of an N-terminally extended 17-kDa PR species caused a severe defect in Gag polyprotein processing and a complete loss of viral infectivity. We conclude that N-terminal release of PR from the HIV-1 polyprotein is essential for viral replication and suggest that extended versions of PR may have a transient function in the proteolytic cascade.