bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Ectodomain of a Novel Member of the Immunoglobulin Subfamily Related to the Poliovirus Receptor Has the Attributes of a Bona Fide Receptor for Herpes Simplex Virus Types 1 and 2 in Human Cells
Authors: Cocchi Francesca , Menotti Laura , Mirandola Prisco , Lopez Marc , Campadelli-Fiume Gabriella 
Published: December 2019

ABSTRACT
We report on the functional cloning of a hitherto unknown member of the immunoglobulin (Ig) superfamily selected for its ability to confer susceptibility to herpes simplex virus (HSV) infection on a highly resistant cell line (J1.1-2 cells), derived by exposure of BHKtk− cells to a recombinant HSV-1 expressing tumor necrosis factor alpha (TNF-α). The sequence of herpesvirus Ig-like receptor (HIgR) predicts a transmembrane protein with an ectodomain consisting of three cysteine-bracketed domains, one V-like and two C-like. HIgR shares its ectodomain with and appears to be an alternative splice variant of the previously described protein PRR-1 (poliovirus receptor-related protein). Both HIgR and PRR-1 conferred on J1.1-2 cells susceptibility to HSV-1, HSV-2, and bovine herpesvirus 1. The viral ligand of HIgR and PRR-1 is glycoprotein D, a constituent of the virion envelope long known to mediate viral entry into cells through interaction with cellular receptor molecules. Recently, PRR-1, renamed HveC (herpesvirus entry mediator C), and the related PRR-2, renamed HveB, were reported to mediate the entry of HSV-1, HSV-2, and bovine herpesvirus 1, and the homologous poliovirus receptor was reported to mediate the entry of pseudorabies virus (R. J. Geraghty, C. Krummenacher, G. H. Cohen, R. J. Eisenberg, and P. G. Spear, Science 280:1618–1620, 1998; M. S. Warner, R. J. Geraghty, W. M. Martinez, R. I. Montgomery, J. C. Whitbeck, R. Xu, R. J. Eisenberg, G. H. Cohen, and P. G. Spear, Virology 246:179–189, 1998). Here we further show that HIgR or PRR-1 proteins detected by using a monoclonal antibody to PRR-1 are widely distributed among human cell lines susceptible to HSV infection and commonly used for HSV studies. The monoclonal antibody neutralized virion infectivity in cells transfected with HIgR or PRR-1 cDNA, as well as in the human cell lines, indicating a direct interaction of virions with the receptor molecule, and preliminarily mapping this function to the ectodomain of HIgR and PRR-1. Northern blot analysis showed that HIgR or PRR-1 mRNAs were expressed in human tissues, with the highest expression being detected in nervous system samples. HIgR adds a novel member to the cluster of Ig superfamily members able to mediate the entry of alphaherpesviruses into cells. The wide distribution of HIgR or PRR-1 proteins among human cell lines susceptible to HSV infection, coupled with the neutralizing activity of the antibody in the same cells, provides direct demonstration of the actual use of this cluster of molecules as HSV-1 and HSV-2 entry receptors in human cell lines. The high level of expression in samples from nervous system makes the use of these proteins in human tissues very likely. This cluster of molecules may therefore be considered to constitute bona fide receptors for HSV-1 and HSV-2.
Transcription Mapping of the Kaposi’s Sarcoma-Associated Herpesvirus (Human Herpesvirus 8) Genome in a Body Cavity-Based Lymphoma Cell Line (BC-1)
Authors: Sarid Ronit , Flore Ornella , Bohenzky Roy A. , Chang Yuan , Moore Patrick S. 
Published: December 2019

ABSTRACT
Kaposi’s sarcoma-associated herpesvirus (KSHV) gene transcription in the BC-1 cell line (KSHV and Epstein-Barr virus coinfected) was examined by using Northern analysis with DNA probes extending across the viral genome except for a 3-kb unclonable rightmost region. Three broad classes of viral gene transcription have been identified. Class I genes, such as those encoding the v-cyclin, latency-associated nuclear antigen, and v-FLIP, are constitutively transcribed under standard growth conditions, are unaffected by tetradecanoylphorbol acetate (TPA) induction, and presumably represent latent viral transcripts. Class II genes are primarily clustered in nonconserved regions of the genome and include small polyadenylated RNAs (T0.7 and T1.1) as well as most of the virus-encoded cytokines and signal transduction genes. Class II genes are transcribed without TPA treatment but are induced to higher transcription levels by TPA treatment. Class III genes are primarily structural and replication genes that are transcribed only following TPA treatment and are presumably responsible for lytic virion production. These results indicate that BC-1 cells have detectable transcription of a number of KSHV genes, particularly nonconserved genes involved in cellular signal transduction and regulation, during noninduced (latent) virus culture.
A Nonessential African Swine Fever Virus Gene
UK
Is a Significant Virulence Determinant in Domestic Swine
Authors: Zsak L. , Caler E. , Lu Z. , Kutish G. F. , Neilan J. G. , Rock D. L. 
Published: December 2019

ABSTRACT

Sequence analysis of the right variable genomic region of the pathogenic African swine fever virus (ASFV) isolate E70 revealed a novel gene,
UK
, that is immediately upstream from the previously described ASFV virulence-associated gene
NL-S
(L. Zsak, Z. Lu, G. F. Kutish, J. G. Neilan, and D. L. Rock, J. Virol. 70:8865–8871, 1996).
UK
, transcriptionally oriented toward the right end of the genome, predicts a protein of 96 amino acids with a molecular mass of 10.7 kDa. Searches of genetic databases did not find significant similarity between
UK
and other known genes. Sequence analysis of the
UK
genes from several pathogenic ASFVs from Europe, the Caribbean, and Africa demonstrated that this gene was highly conserved among diverse pathogenic isolates, including those from both tick and pig sources. Polyclonal antibodies raised against the UK protein specifically precipitated a 15-kDa protein from ASFV-infected macrophage cell cultures as early as 2 h postinfection. A recombinant
UK
gene deletion mutant, ΔUK, and its revertant, UK-R, were constructed from the E70 isolate to study gene function. Although deletion of
UK
did not affect the growth characteristics of the virus in macrophage cell cultures, ΔUK exhibited reduced virulence in infected pigs. While mortality among parental E70- or UK-R-infected animals was 100%, all ΔUK-infected pigs survived infection. Fever responses were comparable in E70-, UK-R-, and ΔUK-infected groups; however, ΔUK-infected animals exhibited significant, 100- to 1,000-fold, reductions in viremia titers. These data indicate that the highly conserved
UK
gene of ASFV, while being nonessential for growth in macrophages in vitro, is an important viral virulence determinant for domestic pigs.
The Pokeweed Antiviral Protein Specifically Inhibits Ty
1
-Directed +1 Ribosomal Frameshifting and Retrotransposition in
Saccharomyces cerevisiae
Authors: Tumer Nilgun E. , Parikh Bijal A. , Li Ping , Dinman Jonathan D. 
Published: December 2019

ABSTRACT

Programmed ribosomal frameshifting is a molecular mechanism that is used by many RNA viruses to produce Gag-Pol fusion proteins. The efficiency of these frameshift events determines the ratio of viral Gag to Gag-Pol proteins available for viral particle morphogenesis, and changes in ribosomal frameshift efficiencies can severely inhibit virus propagation. Since ribosomal frameshifting occurs during the elongation phase of protein translation, it is reasonable to hypothesize that agents that affect the different steps in this process may also have an impact on programmed ribosomal frameshifting. We examined the molecular mechanisms governing programmed ribosomal frameshifting by using two viruses of the yeast
Saccharomyces cerevisiae
. Here, we present evidence that pokeweed antiviral protein (PAP), a single-chain ribosomal inhibitory protein that depurinates an adenine residue in the α-sarcin loop of 25S rRNA and inhibits translocation, specifically inhibits Ty
1
-directed +1 ribosomal frameshifting in intact yeast cells and in an in vitro assay system. Using an in vivo assay for Ty
1
retrotransposition, we show that PAP specifically inhibits Ty
1
retrotransposition, suggesting that Ty
1
viral particle morphogenesis is inhibited in infected cells. PAP does not affect programmed −1 ribosomal frameshift efficiencies, nor does it have a noticeable impact on the ability of cells to maintain the M
1
-dependent killer virus phenotype, suggesting that −1 ribosomal frameshifting does not occur after the peptidyltransferase reaction. These results provide the first evidence that PAP has viral RNA-specific effects in vivo which may be responsible for the mechanism of its antiviral activity.
Resistance to Virus Infection Conferred by the Interferon-Induced Promyelocytic Leukemia Protein
Authors: Chelbi-Alix Mounira K. , Quignon Frédérique , Pelicano Luis , Koken Marcel H. M. , de Thé Hugues 
Published: December 2019

ABSTRACTThe interferon (IFN)-induced promyelocytic leukemia (PML) protein is specifically associated with nuclear bodies (NBs) whose functions are yet unknown. Two of the NB-associated proteins, PML and Sp100, are induced by IFN. Here we show that overexpression of PML and not Sp100 induces resistance to infections by vesicular stomatitis virus (VSV) (a rhabdovirus) and influenza A virus (an orthomyxovirus) but not by encephalomyocarditis virus (a picornavirus). Inhibition of viral multiplication was dependent on both the level of PML expression and the multiplicity of infection and reached 100-fold. PML was shown to interfere with VSV mRNA and protein synthesis. Compared to the IFN mediator MxA protein, PML had less powerful antiviral activity. While nuclear body localization of PML did not seem to be required for the antiviral effect, deletion of the PML coiled-coil domain completely abolished it. Taken together, these results suggest that PML can contribute to the antiviral state induced in IFN-treated cells.
Differential Requirements for Conserved E2 Binding Sites in the Life Cycle of Oncogenic Human Papillomavirus Type 31
Authors: Stubenrauch Frank , Lim Hock B. , Laimins Laimonis A. 
Published: December 2019

ABSTRACT
Human papillomavirus (HPV) E2 proteins regulate viral replication by binding to sites in the upstream regulatory region (URR) and by complex formation with the E1 origin recognition protein. In the genital HPV types, the distribution and location of four E2 binding sites (BS1 to BS4) which flank a single E1 binding site are highly conserved. We have examined the roles of these four E2 sites in the viral life cycle of HPV type 31 (HPV31) by using recently developed methods for the biosynthesis of papillomaviruses from transfected DNA templates (M. G. Frattini et al., Proc. Natl. Acad. Sci. USA 93:3062–3067, 1996). In transient assays, no single site was found to be necessary for replication, and mutation of the early promoter-proximal site (BS4) led to a fourfold increase in replication. Cotransfection of the HPV31 wild-type (HPV-wt) and mutant genomes with expression vectors revealed that E1 stimulated replication of HPV31-wt as well as the HPV31-BS1, -BS2, and -BS3 mutants. In contrast, increased expression of E2 decreased replication of these genomes. Replication of the HPV31-BS4 mutant genome was not further increased by cotransfection of E1 expression vectors but was stimulated by E2 coexpression. In stably transfected normal human keratinocytes, mutation of either BS1, BS3, or BS4 resulted in integration of viral genomes into host chromosomes. In contrast, mutation of BS2 had no effect on stable maintenance of episomes or copy number. Following growth of stably transfected lines in organotypic raft cultures, the differentiation-dependent induction of late gene expression and amplification of viral DNA of the BS2 mutant was found to be similar to that of HPV31-wt. We were unable to find a role for BS2 in our assays for viral functions. We conclude that at least three of the four E2 binding sites in the URRs of HPVs are essential for the productive viral life cycle. The specific arrangement of E2 binding sites within the URR appears to be more important for viral replication than merely the number of sites.
The Major Site of Phosphorylation within the Rous Sarcoma Virus MA Protein Is Not Required for Replication
Authors: Nelle Timothy D. , Verderame Michael F. , Leis Jonathan , Wills John W. 
Published: December 2019

ABSTRACT

About one-third of the MA protein in Rous sarcoma virus (RSV) is phosphorylated. Previous analyses of this fraction have suggested that serine residues 68 and 106 are the major sites of phosphorylation. As a follow-up to that study, we have characterized mutants which have these putative phosphorylation sites changed to alanine, either separately or together. None of the substitutions (S68A, S106A, or S68/106A) had an effect on the budding efficiency or infectivity of the virus. Upon examination of the
32
P-labeled viral proteins, we found that the S68A substitution did not affect phosphorylation in vivo at all. In contrast, the S106A substitution prevented all detectable phosphorylation of MA, suggesting that there is only one major site of phosphorylation in MA. We also found that the RSV MA protein is phosphorylated on tyrosine, but the amount was low and detectable only with large numbers of virions and an antibody specific for phosphotyrosine.
Relative Importance of Rotavirus-Specific Effector and Memory B Cells in Protection against Challenge
Authors: Moser Charlotte A. , Cookinham Sarah , Coffin Susan E. , Clark H. Fred , Offit Paul A. 
Published: December 2019

ABSTRACTAdult BALB/c mice were orally inoculated with murine (strain EDIM), simian (strain RRV), or bovine (strain WC3) rotavirus. Six or 16 weeks after inoculation, mice were challenged with EDIM. At the time of challenge and in the days immediately following challenge, production of rotavirus-specific immunoglobulin A (IgA), IgG, and IgM by small intestinal lamina propria lymphocytes (LPL) was determined by fragment culture, and quantities of virus-specific antibodies at the intestinal mucosal surface were determined by intestinal lavage. Mice immunized with EDIM were completely protected against EDIM challenge both 6 and 16 weeks after immunization. Protection was associated with production of high levels of IgA by LPL and detection of virus-specific IgA at the intestinal mucosal surface. In addition, animals immunized and later challenged with EDIM did not develop a boost in antibody responses, suggesting that they were also not reinfected. We also found that in mice immunized with nonmurine rotaviruses, (i) quantities of virus-specific IgA generated following challenge were greater 16 weeks than 6 weeks after immunization, (ii) immunization enhanced the magnitude but did not hasten the onset of production of high quantities of virus-specific IgA by LPL after challenge, and (iii) immunization induced partial protection against challenge; however, protection was not associated with either production of virus-specific antibodies by LPL or detection of virus-specific antibodies at the intestinal mucosal surface.
Human Papillomavirus Oncoproteins E6 and E7 Independently Abrogate the Mitotic Spindle Checkpoint
Authors: Thomas Jennifer T. , Laimins Laimonis A. 
Published: December 2019

ABSTRACT

The E6 and E7 genes of the high-risk human papillomavirus (HPV) types encode oncoproteins, and both act by interfering with the activity of cellular tumor suppressor proteins. E7 proteins act by associating with members of the retinoblastoma family, while E6 increases the turnover of p53. p53 has been implicated as a regulator of both the G
1
/S cell cycle checkpoint and the mitotic spindle checkpoint. When fibroblasts from p53 knockout mice are treated with the spindle inhibitor nocodazole, a rereplication of DNA occurs without transit through mitosis. We investigated whether E6 or E7 could induce a similar loss of mitotic checkpoint activity in human keratinocytes. Recombinant retroviruses expressing high-risk E6 alone, E7 alone, and E6 in combination with E7 were used to infect normal human foreskin keratinocytes (HFKs). Established cell lines were treated with nocodazole, stained with propidium iodide, and analyzed for DNA content by flow cytometry. Cells infected with high-risk E6 were found to continue to replicate DNA and accumulated an octaploid (8N) population. Surprisingly, expression of E7 alone was also able to bypass this checkpoint. Cells expressing E7 alone exhibited increased levels of p53, while those expressing E6 had significantly reduced levels. The p53 present in the E7 cells was active, as increased levels of p21 were observed. This suggested that E7 bypassed the mitotic checkpoint by a p53-independent mechanism. The levels of MDM2, a cellular oncoprotein also implicated in control of the mitotic checkpoint, were significantly elevated in the E7 cells compared to the normal HFKs. In E6-expressing cells, the levels of MDM2 were undetectable. It is possible that abrogation of Rb function by E7 or increased expression of MDM2 contributes to the loss of mitotic spindle checkpoint control in the E7 cells. These findings suggest mechanisms by which both HPV oncoproteins contribute to genomic instability at the mitotic checkpoint.
Regulation of Human Immunodeficiency Virus Replication by 2′,5′-Oligoadenylate-Dependent RNase L
Authors: Maitra Ratan K. , Silverman Robert H. 
Published: December 2019

ABSTRACTActivation of RNase L by 2′,5′-linked oligoadenylates (2-5A) is one of the antiviral pathways of interferon action. To determine the involvement of the 2-5A system in the control of human immunodeficiency virus type 1 (HIV-1) replication, a segment of the HIV-1nefgene was replaced with human RNase L cDNA. HIV-1 provirus containing sense orientation RNase L cDNA caused increased expression of RNase L and 500- to 1,000-fold inhibition of virus replication in Jurkat cells for a period of about 2 weeks. Subsequently, a partial deletion of the RNase L cDNA which coincided with increases in virus production occurred. The anti-HIV activity of RNase L correlated with decreases in HIV-1 RNA and with an acceleration in cell death accompanied by DNA fragmentation. Replication of HIV-1 encoding RNase L was also transiently suppressed in peripheral blood lymphocytes (PBL). In contrast, recombinant HIV containing reverse orientation RNase L cDNA caused decreased levels of RNase L, increases in HIV yields, and reductions in the anti-HIV effect of alpha interferon in PBL and in Jurkat cells. To obtain constitutive and continuous expression of RNase L cDNA, Jurkat cells were cotransfected with HIV-1 proviral DNA and with plasmid containing a cytomegalovirus promoter driving expression of RNase L cDNA. The RNase L plasmid suppressed HIV-1 replication by eightfold, while an antisense RNase L construct enhanced virus production by twofold. These findings demonstrate that RNase L can severely impair HIV replication and suggest involvement of the 2-5A system in the anti-HIV effect of alpha interferon.
Inhibition of p53 Transactivation Function by the Human T-Cell Lymphotropic Virus Type 1 Tax Protein
Authors: Pise-Masison Cynthia A. , Choi Kyeong-Sook , Radonovich Michael , Dittmer Jürgen , Kim Seong-Jin , Brady John N. 
Published: December 2019

ABSTRACT
Human T-cell lymphotropic virus type 1 (HTLV-1) is the etiologic agent for adult T-cell leukemia. HTLV-1 transforms lymphocytes, and there is increasing evidence that the virus-encoded protein, Tax, plays a primary role in viral transformation. We have shown that wild-type p53 in HTLV-1-transformed cells is stabilized. This study was initiated to directly analyze whether the p53 in HTLV-1-transformed cell lines was transcriptionally active and to identify the viral gene product responsible for stabilization and inactivation. Transfection experiments using a p53-responsive reporter plasmid and γ-irradiation studies demonstrate that the wild-type p53 in HTLV-1-transformed cell lines is not fully active. Further, we demonstrate that the HTLV-1-transforming protein, Tax, stabilizes and inactivates p53 function. Cotransfection of Tax with p53 results in a greater than 10-fold reduction in p53 transcription activity. Using Gal4-p53 fusion proteins, we demonstrate that Tax inhibition of p53 transactivation function is independent of sequence-specific DNA binding. Moreover, Tax inhibits p53 function by interfering with the activity of the N-terminal activation domain (amino acids 1 to 52). We conclude that Tax is involved in the inactivation of p53 function and stabilization of p53 in HTLV-1-infected cells. The functional interference of p53 function by Tax may be important for transformation and leukemogenesis.
Use of Differential Display Reverse Transcription-PCR To Reveal Cellular Changes during Stimuli That Result in Herpes Simplex Virus Type 1 Reactivation from Latency: Upregulation of Immediate-Early Cellular Response Genes TIS7, Interferon, and Interferon Regulatory Factor-1
Authors: Tal-Singer Ruth , Podrzucki Wawrzyniec , Lasner Todd M. , Skokotas Aikaterini , Leary Jeffry J. , Fraser Nigel W. , Berger Shelley L. 
Published: December 2019

ABSTRACTThe detailed mechanism which governs the choice between herpes simplex virus (HSV) latency and reactivation remains to be elucidated. It is probable that altered expression of cellular factors in sensory neurons leads to induction of HSV gene expression resulting in reactivation. As an approach to identify novel cellular genes which are activated or repressed by stimuli that reactivate HSV from latency and hence may play a role in viral reactivation, RNA from explanted trigeminal ganglia (TG) was analyzed by differential display reverse transcription-PCR (DDRT-PCR). Nearly 50 cDNAs whose mRNA level was modified by the stress of explantation were isolated and sequenced. We present a listing of a spectrum of altered RNAs, including both known and unknown sequences. Five of those differentially displayed transcripts were identified as interferon-related murine TIS7 mRNA. These results were confirmed in both infected and uninfected ganglia by quantitative RNase protection assay and immunostaining. Alpha and beta interferons and interferon regulatory factor-1 (IRF-1) were also induced by explantation. In addition, we have identified sequences that correspond to IRF-1 consensus binding sites in both HSV type 1 origins of replication. Our findings suggest that physiological pathways that include these cellular factors may be involved in modulating HSV reactivation.