pinecone/core-2020-05-10-deduplication huggingface dataset:
Epstein–Barr Virus Permissively Infects Human Syncytiotrophoblastsin Vitroand Induces Replication of Human T Cell Leukemia-Lymphoma Virus Type I in Dually Infected Cells

AbstractEpstein–Barr virus (EBV) and human immunodeficiency virus type 1 (HIV-1), as well as human T-cell leukemia-lymphoma virus type I (HTLV-I), may interact in the pathogenesis of human retroviral infections. The placental syncytiotrophoblast layer represents a barrier protecting the fetal compartment from exposure to retroviruses. We studied the interactions of EBV with HIV-1 and HTLV-I in human term syncytiotrophoblast cells to investigate the significance of double infections in transplacental transmission of human retroviruses. We found that syncytiotrophoblast cells could be productively infected with EBV. Dual infection of the cells with EBV and HTLV-I resulted in full replication cycle of otherwise latent HTLV-I. In contrast, the restricted permissiveness of syncytiotrophoblasts for HIV-1 was not influenced by coinfection of the cells with EBV. Infection of syncytiotrophoblast cells with EBV, but not HTLV-I, induced interleukin-2 and interleukin-6 secretion, and augmented secretion occurred on coinfection with both viruses. Coinfection of syncytiotrophoblast cells with EBV and HTLV-I induced tumor necrosis factor-β and transforming growth factor-β1 secretion, but infection with either virus alone did not lead to secretion of these cytokines. Permissive replication cycle of HTLV-I was induced by the EBV immediate-early gene product Zta. Pseudotype formation between EBV and HTLV-I in coinfected syncytiotrophoblast cells was not found. Our data suggest that activation of HTLV-I gene expression by EBV in coinfected syncytiotrophoblast cells may be a mechanism for transplacental transmission of HTLV-I
Efficient Delivery of Circulating Poliovirus to the Central Nervous System Independently of Poliovirus Receptor

AbstractThe transgenic (Tg) mice carrying the human gene for poliovirus receptor (PVR) are susceptible to poliovirus intravenously (IV) inoculated as well as intracerebrally or intraspinally inoculated. Thus, IV-inoculated poliovirus may invade the central nervous system (CNS) through the blood–brain barrier (BBB). To know the contribution of PVR to tissue distribution and BBB permeability of IV-inoculated polioviruses, these dissemination processes were investigated and compared between the Tg mice and non-Tg mice. Distribution profile of IV-inoculated poliovirus in various tissues of the Tg mice is similar to that in non-Tg mice. The data suggest that tissue distribution of the virus occurs independently of the transgene for PVR. The amount of poliovirus delivered to the CNS suggested the existence of a specific delivery system of the virus to the CNS. Virus accumulation in the CNS of the Tg mice was measured up to 7.5 hr after the IV inoculation. The viruses, regardless of whether the virulent or attenuated strain, seem to accumulate at a constant rate of approximately 0.2 μl/min/g tissue. Similar phenomena were observed when the viruses were inoculated into non-Tg mice. The rates of the virus accumulation in the CNS are more than 100 times higher than that of albumin, which is considered not to permeate through the BBB via a specific transport system, and only three times lower than that of monoclonal antibody against transferrin receptor (OX-26), which is a potential candidate as a drug delivery vehicle specific to the CNS. These data suggest that polioviruses permeate through the BBB at a fairly high rate, independently of PVR and virus strains
Construction of Ovine Adenovirus Recombinants by Gene Insertion or Deletion of Related Terminal Region Sequences

AbstractAn ovine adenovirus which may be the prototype for a new group of adenoviruses has been engineered as a gene transfer vector. One recombinant containing a 0.95-kb insertion expressed a sheep parasite antigen from the ovine adenovirus major late promoter and tripartite leader sequences. It was shown that insertions of at least 4.3 kb were tolerated at either one of two sites in the genome without the introduction of a compensating deletion. The unique structure of this viral genome was further emphasized by the discovery that four open reading frames at the right hand end show significant identity to each other but not to other sequences in the databases. Two other unrelated open reading frames were also present. RT-PCR analysis identified two transcripts in this region which were derived from a promoter which was located very close to, or within the ITR sequence. Splicing removed all but the first and last of the ORFs from these RNAs, suggesting that some sequences might be nonessential for replicationin vitro.A ∼2-kb deletion, which removed or truncated the internal reading frames was introduced into the region without affecting virus viability. The carrying capacity of OAV recombinants should therefore be at least 6.3 kb. The relative packaging capacity of OAV (114%) therefore exceeds that of Ad5 (105%), although a comparison of virus particle sizes by electron microscopy showed that OAV was smaller than Ad5. These studies improve the potential utility of OAV as a gene transfer vector
Cell Membrane Vesicles Are a Major Contaminant of Gradient-Enriched Human Immunodeficiency Virus Type-1 Preparations

AbstractDuring preliminary experiments to establish the proportion of virus-coded p24 protein to virus membrane-associated HLA-DR in gradient-enriched HIV-1 preparations, we became aware of a large variability between experiments. In order to determine whether HLA-DR-containing cellular material was contaminating the virus preparations, we carried out enrichment by gradient centrifugation of clarified supernatants from noninfected cells and tested this material for HLA-DR content. We found that, independently of the cell type used, gradient enrichment resulted in the isolation of large quantities of HLA-DR-containing material which banded at a density overlapping that of infectious HIV. Electron microscopy of gradient-enriched preparations from supernatants of virus-infected cells revealed an excess of vesicles with a size range of about 50–500 nm, as opposed to a minor population of virus particles of about 100 nm. Electron micrographs of infected cells showed polarized vesiculation of the cell membrane, and virus budding was frequently colocalized with nonviral membrane vesiculation. Analysis of the cellular molecules present in the fractions containing virus or exclusively cellular material demonstrated that virus and cellular vesicles share several cellular antigens, with the exception of CD43 and CD63, found mainly at the virus surface, and HLA-DQ, which was found only in the cellular vesicles
RNase H Cleavage of tRNAProMediated by M-MuLV and HIV-1 Reverse Transcriptases

AbstractRNA–DNA hybrid model substrates which mimic an intermediate of Moloney murine leukemia virus (M-MuLV) reverse transcription at the stage where the tRNAProis removed were constructed. This substrate was used to assay the ability of M-MuLV reverse transcriptase (RT) to cleave the RNA portion of the substrate. The cleavage specificities of the cognate M-MuLV RT and the heterologous enzyme from the human immunodeficiency virus type-1 (HIV-1) were compared. M-MuLV and HIV-1 RT recognize and cleave the RNA at distinct positions. The site of the initial RNase H cleavagein vitrowas determined using 3′ end nearest neighbor analysis of the initial cleavage product. M-MuLV RT/RNase H removed the model tRNAProbetween the terminal ribo-A and ribo-C, resulting in a terminal ribo-A attached to the viral DNA, whereas HIV-1 RT/RNase H was shown to cleave at the RNA–DNA junction. Analysis of the DNA over time indicated that the ribo-A is subsequently removed by M-MuLV RT.In vivoanalysis from double-LTR circle junctions illustrated that 16 of the 23 clones isolated possessed the predicted junction if complete removal of the tRNA primer were to occur. The predicted junction for complete removal of the tRNA primer was CATT-AATG. One aberrant circle junction was isolated which could result from the use of an alternative primer. In contrast with HIV, no M-MuLV circle junctions were isolated which indicated processing of a single-LTR terminus by integrase. Analysis fromin vivoandin vitrostudies indicate that the M-MuLV tRNAProprimer is completely removed after plus-strand strong-stop synthesis
The Complete DNA Sequence of Lymphocystis Disease Virus

AbstractLymphocystis disease virus (LCDV) is the causative agent of lymphocystis disease, which has been reported to occur in over 100 different fish species worldwide. LCDV is a member of the familyIridoviridaeand the type species of the genus Lymphocystivirus. The virions contain a single linear double-stranded DNA molecule, which is circularly permuted, terminally redundant, and heavily methylated at cytosines in CpG sequences. The complete nucleotide sequence of LCDV-1 (flounder isolate) was determined by automated cycle sequencing and primer walking. The genome of LCDV-1 is 102.653 bp in length and contains 195 open reading frames with coding capacities ranging from 40 to 1199 amino acids. Computer-assisted analyses of the deduced amino acid sequences led to the identification of several putative gene products with significant homologies to entries in protein data banks, such as the two major subunits of the viral DNA-dependent RNA polymerase, DNA polymerase, several protein kinases, two subunits of the ribonucleoside diphosphate reductase, DNA methyltransferase, the viral major capsid protein, insulin-like growth factor, and tumor necrosis factor receptor homolog
Deletion Analysis of Four of Eighteen Late Gene Expression Factor Gene Homologues of the Baculovirus, BmNPV

AbstractNucleotide sequence analysis of the genome of the baculovirusBombyx morinuclear polyhedrosis virus (BmNPV) identified 18 homologues of theAutographa californicaNPV (AcNPV)lefs (late expression factor genes). These BmNPVlefs showed high (73–98%) amino acid sequence identities to AcNPVlefs and were localized to similar positions in the genome. Onelef, p35,was previously characterized in AcNPV and BmNPV deletion experiments. Functional deletion of each of the BmNPVlefhomologues was attempted here by insertion of a β-galactosidase gene cassette into the coding region of eachlef.Four of 18 BmNPVlef(39K, ie-2, lef-7,andp35) deletion mutants were successfully isolated, indicating that the other 14 BmNPVlefs were likely essential for viral replication in cell culture. Further analysis showed that deletion oflef-7, p35,andie-2resulted in lower levels of viral DNA replication, indicating that the BmNPVlef-7, p35,andie-2products have stimulating effects on DNA replication. Deletion of39Kresulted in a significantly lower level of late gene transcription and extremely low (over 102-fold less at 48–80 hr p.i.) production of progeny budded virus in BmN cells. In contrast, the deletion did not affect viral DNA replication, indicating that BmNPV39Kis involved in late gene transcription. Reduced late gene expression presumably affected production and/or release of progeny budded virus particles. This was corroborated by transmission electron microscopy, which showed that virus replication was abnormal in BmN cells infected with a BmNPV mutant lacking39Kand virion production was low. Even though39Kdeletion resulted in a loss of oral infectivity, the39Kdeletion mutant replicated in silkworm larvae when injected into the body cavity, as did theie-2, lef7,andp35deletion mutants. In addition, a BmNPV homologue of the baculovirus very late expression factor gene (vlf-1) found in AcNPV was essential, implying an essential function of the BmNPVvlf-1homologue at a step before the onset of very late gene expression
Viral Persistent Infection Affects both Transcriptional and Posttranscriptional Regulation of Neuron-Specific Molecule GAP43

AbstractRecently, we reported thatin vitroandin vivopersistent infection of neurons by lymphocytic choriomeningitis virus (LCMV) downregulated GAP43 expression, a protein involved in neuronal plasticity associated with learning and memory. Here, we investigated the transcriptional and posttranscriptional events involved. Persistent LCMV infection of PC12 cells (PC12Pi) caused reduced levels of GAP43 steady-state mRNA when compared to uninfected PC12 cells. In addition, an increase in the steady-state levels of GAP43 mRNA observed in PC12 cells in response to nerve growth factor (NGF) was abrogated in PC12Pi cells. Nuclear run-on analysis revealed that the rate of GAP43 transcription was reduced threefold in PC12Pi cells compared to uninfected PC12 cells. Moreover, analysis of the half-life of GAP43 mRNA indicated that NGF-mediated stabilization of GAP43 transcripts was significantly diminished in PC12Pi cells. Treatment of PC12Pi cells with basic fibroblast growth factor, dibutyryl cyclic AMP, and 12-o-tetradecanoyl-phorbol-13-acetate, a potent activator of protein kinase C, did not increase the GAP43 mRNA steady-state level, suggesting that LCMV infection interferes with a step downstream from protein kinases A and C in the NGF signal transduction pathway
Cell Cycle Inhibitory Effects of HIV and SIV Vpr and Vpx in the YeastSchizosaccharomyces pombe

AbstractThe Vpr gene of human immunodeficiency virus type 1 and type 2 (HIV-1, HIV-2) and simian immunodeficiency virus (SIV) encodes a small nuclear protein which is virion-associated and assists nuclear transport of the preintegration complex. Expression of HIV-1 Vpr has been shown to induce differentiation and prevent proliferation of human cells. HIV-1 Vpr has also been shown to arrest cell growth and cause morphological defects in yeast. In contrast, the Vpx gene of HIV-2 and SIV, which shares sequence homology with Vpr, does not seem to inhibit proliferation of human cells. It has been suggested that the cell cycle arrest effect of Vpr and Vpx is species and cell-type dependent. In this study, we have taken advantage of a conditional expression system to characterize the growth inhibitory effects of Vpr and Vpx of HIV-1, HIV-2, and SIV in the fission yeastSchizosaccharomyces pombe.Our results show that both Vpr and/or Vpx of HIV-1, HIV-2, and SIV arrest cell growth inS. pombe,and HIV-1 Vpr is more cytotoxic than HIV-2 or SIV Vpr or Vpx. Flow cytometry analysis indicated that yeast cells cease proliferating with DNA contents indicative of arrest in G1and G2, with some cells showing signs of overreplication of DNA. While the observed cell cycle arrest phenotype was not identical to that observed in mammalian cells, there were similarities of growth arrest phenotype caused by Vpr and Vpx in yeast and mammalian cells. Specifically, the observation that yeast and mammalians cell both arrest in G2with reduced p34/cdc2kinase activity indicates that Vpr and Vpx interact with conserved target(s) in yeast and mammalian cells. The ability to use genetic analysis to elucidate the mechanisms involved makesS. pombean excellent model system in which to study the effects of Vpr and Vpx on cellular function
Recombinant Genomic RNA of Coronavirus MHV-A59 after Coreplication with a DI RNA Containing the MHV-RI Spike Gene

AbstractA strategy for targeted RNA recombination between the spike gene on the genomic RNA of MHV-A59 and a synthetic DI RNA containing the MHV-RI spike gene is described. The MHV-RI spike gene contains several nucleotide differences from the MHV-A59 spike gene that could be used as genetic markers, including a stretch of 156 additional nucleotides starting at nucleotide 1497. The MHV-RI S gene cDNA (from nucleotide 277-termination codon) was inserted in frame into pMIDI, a full-length cDNA clone of an MHV-A59 DI, yielding pDPRIS. Using the vaccinia vTF7.3 system, RNA was transcribed from pDPRIS upon transfection into MHV-A59-infected L cells. DPRIS RNA was shown to be replicated and passaged efficiently. MHV-A59 and the DPRIS DI particle were copassaged several times. Using a highly specific and sensitive RT-PCR, recombinant genomic RNA was detected in intracellular RNA from total lysates of pDPRIS-transfected and MHV-A59-infected cells and among genomic RNA that was agarose gel-purified from these lysates. More significantly, specific PCR products were found in virion RNA from progeny virus. PCR products were absent in control mixes of intracellular RNA from MHV-A59-infected cells andin vitro-transcribed DPRIS RNA. PCR products from intracellular RNA and virion RNA were cloned and 11 independent clones were sequenced. Crossovers between A59 and RI RNA were found upstream of nucleotide 1497 and had occurred between 106 nucleotides from the 5′-border and 73 nucleotides from the 3′-border of sequence homologous between A59 and RI S genes. We conclude that homologous RNA recombination took place between the genomic RNA template and the synthetic DI RNA template at different locations, generating a series of MHV recombinant genomes with chimeric S genes
Five New or Recently Discovered (GBV-A) Virus Species Are Indigenous to New World Monkeys and May Constitute a Separate Genus of theFlaviviridae

AbstractIn previous studies, human hepatitis viruses have been experimentally transmitted to New World monkeys of the genusSaguinus(tamarins). Recently, twoFlaviviridae-like agents (GBV-A and GBV-B) were identified in tamarins that developed hepatitis following inoculation with serum of the 11th tamarin passage of a potentially new human hepatitis agent. However, it was not shown that these viruses originated from the initial inoculum. We here report the discovery of indigenous species-specific viruses related to GBV-A in several species of New World monkeys and suggest that GBV-A virus was fortuitously acquired during passage in tamarins. Sera or plasma from 98 wild-caught New World monkeys representing 10 different species was tested by RT-PCR with conserved degenerate primers to the 5′ noncoding region of the genome. Viral sequences were identified in 33 animals and sequence analysis was performed on the amplicons. In addition, the genomic region corresponding to the putative NS3 RNA helicase of GBV-A was amplified from most positive animals and sequenced. We detected GBV-A-like viruses in 13 (35%) of 37S. mystax,7 (78%) of 9S. nigricollis,3 (25%) of 12S. labiatus,2 (50%) of 4S. oedipus,2 (100%) of 2Callithrix jacchus,and 6 (50%) of 12Aotus trivirgatusmonkeys. Each positive animal was infected with a unique strain of the GBV-A-like viruses. Analysis of the 5′ NC and NS3 helicase sequences revealed that these viruses could be classified into 5 major genetic groups with genetic distances equivalent to or greater than those found among major genetic groups of hepatitis C virus. Species-specific GBV-A-like viruses were found inS. mystax, S. nigricollis, S. oedipus, C. jacchus,andA. trivirgatusspecies. The viruses specific forS. nigricolliswere closely related to GBV-A, suggesting that GBV-A was acquired by passage through this species during the initial transmission studies. The natural history of the GBV-A-like viruses was studied in serial serum samples from 9S. mystaxand 2A. trivirgatusmonkeys. Each animal was chronically infected and the viral strain did not vary during 9–27 months of follow-up. Finally, we demonstrated that fourS. mystaxwere positive upon arrival to the United States from the country of origin. No apparent disease was associated with chronic infection of the GBV-A-like viruses. In conclusion, many New World monkeys are persistently infected with indigenous species-specific viruses that may represent a new genus within the virus familyFlaviviridae
Analyses of Disulfides Present in the Rubella Virus E1 Glycoprotein

AbstractThe surface of Rubella virus contains the glycoproteins E1 and E2. The E1 protein induces neutralizing antibodies and has been implicated in the process of recognition of cellular receptors. To gain information on the structural organization of the E1 protein we have analyzed the disulfide bonds present within this molecule. The reactivity of the protein with radioactively labeled iodoacetic acid indicates that all 20 cysteine residues present in the ectodomain of the E1 protein are involved in disulfide formation. E1 protein was purified by preparative SDS–PAGE under nonreducing conditions from virus particles grown in tissue culture in the presence of [35S]cysteine. The purified protein was digested with a number of proteases followed by reversed phase high-performance liquid chromatography (HPLC). [35S]cysteine-containing peptides were identified and characterized by N-terminal amino acid sequence determination. These analyses identified the following eight disulfide bridges: C(1)–C(2); C(3)–C(15); C(6)–C(7); C(9)–C(10); C(11)–C(12); C(13)–C(14); C(17)–C(18); and C(19)–C(20). The two disulfide bridges formed by the residues C(4), C(5), C(8), and C(16) have not been identified with certainty, but a likely organization can be derived. The data obtained are discussed in the context of a possible structural and functional organization of the E1 protein
Long Terminal Repeat U3 Length Polymorphism of Human Foamy Virus

AbstractSize determination of the long terminal repeat (LTR) of an early (1985) and a more recent (1993) passage of wild-type human foamy virus (HFV) revealed that the virus has undergone substantial deletions in the U3 region upon replication in tissue culture. Two LTR deletion variants (HSRV1 and 2) have been characterized in the past and used to construct molecular clones which are replication competent in cell culture. We now report the molecular cloning, sequencing, and biological characterization of an HFV genome with full-length LTR (pHFV2). Sequence analysis revealed that the deletions in HSRV1 and 2 are nonrandom and probably occurred by misalignment during reverse transcription. The comparative analysis of HFV2 and the variant with the largest U3 deletion, HSRV2, revealed a differential ability to replicate in human cell cultures. While HSRV2 replicated faster in diploid human fibroblasts, cells which have been used extensively for amplification of HFV in the past, replication of HFV2 was faster in a lymphoblastoid cell line. Reporter gene assays indicated that the cell-type specific ability of the LTRs to respond to the viral transcriptional transactivator may be a likely reason for the different growth properties of both viruses and for the occurrence of the HFV U3 deletions. In foamy virus-infected chimpanzees only the full-length type of LTR was observed; however, the HSRV1 deletion variant was detected as the dominating virus in an accidentally HFV-infected human
A Novel Mechanism of Virus–Virus Interactions: Bacteriophage P2 Tin Protein Inhibits Phage T4 DNA Synthesis by Poisoning the T4 Single-Stranded DNA Binding Protein, gp32

AbstractP2 prophages have been known to inhibit DNA replication and growth of T-even phages. We show here that this inhibition is due to poisoning of the T-even single-stranded DNA binding protein gp32 by the product of the nonessential P2tingene. Synthesis of Tin protein from a gene cloned in a multicopy plasmid is necessary and sufficient to completely preventde novoDNA replication and growth of wild-type T2 or T4 phage. We isolated more than 20 independent mutants that render T-even phages resistant to poisoning by the P2 Tin protein. In all of these mutants, which we callasp,Asp codon 163 of gene32is changed to a Gly or Asn codon. The mutant alleles are recessive; i.e., when wild-type andaspmutants coinfect the same host cells, most DNA replication is poisoned by P2 Tin protein. To explain our results, we propose that the P2 Tin protein interacts with T-even gp32 at position 163 and distorts the helical filament of gene32protein on single-stranded DNA. Thereby Tin protein inhibits either assembly or function, or both, of the T4 replisome. The inhibition of late gene expression by P2 Tin protein may be an indirect consequence of inhibition of DNA replication