pinecone/core-2020-05-10-deduplication huggingface dataset:
Bacteriophage P4 Capsid-Size Determination and Its Relationship to P2 Helper Interference

AbstractThesid(sizedetermination) gene product of phage P4 is known to be involved in capsid-size determination. Moreover, the capsid-size determination function interferes with the lytic development of its helper P2, presumably because the helper genome is too large to be packaged into P4-size capsids. In order to study P4-specified helper interference, we cloned thesidgene for expression during phage infection. Even though gpSid restores the capsid-size determination function of asiddefective P4 mutant, we find that gpSid alone is not sufficient to establish full interference of helper P2 phage production. Complete helper interference requires some P4 function in addition to gpSid. Complementation tests show that none of the known P4 genes display this property. We propose that P4 encodes a yet-unidentified function that in concert with gpSid establishes full P2 helper interference at the level of capsid-size determination
Persistence of Vesicular Stomatitis Virus New Jersey RNA in Convalescent Hamsters

AbstractPersistence of vesicular stomatitis virus New Jersey (VSV-NJ) was studied in experimentally infected hamsters (Mesocricetus auratus). We used reverse transcription and nested polymerase chain reaction (RT-NPCR) to probe tissues of hamsters inoculated with VSV-NJ Hazelhurst. Viral genomic RNA was detected in the brain, cerebellum, spleen, liver, kidney, and lung 2 months after infection, but only in the central nervous system at 10 and 12 months. Viral messenger RNA was detected in the brain of one hamster at 2 months after infection. Replicative intermediate was detected in the spinal cord of one hamster at 12 months. These results suggest that VSV-RNA persists in animals for long periods following infection, disease, and convalescence. However, infectious virus was not recovered from tissues by conventional serial passages of tissue extracts in Vero cells or by cocultivation
Rod-Like Shape of Vesicular Stomatitis Virus Matrix Protein

AbstractThe shape of purified matrix protein (M) of vesicular stomatitis virus was determined using biophysical techniques like analytical centrifugation, dynamic light scattering, and small-angle neutron scattering. The data obtained are consistent with a rod-like model for M protein with a length of about 100 ± 10 Å and a radius of 9 ± 1 Å. These dimensions are in agreement with the substructure of M protein aggregates and with the fine morphology of the axial channel material found inside the viral nucleocapsid coil. This morphological information was combined with CD measurements and secondary structure predictions on four vesiculovirus M proteins leading to a proposal for the structure of M protein
Novel NTP Binding Property of Rice Dwarf Phytoreovirus Minor Core Protein P5

AbstractRice dwarf phytoreovirus (RDV) mRNA synthesized from purified virion has a cap structure, m7GpppAm—, which suggests the presence of guanylyltransferase activity in the virion. We attempted to identify the enzyme involved in the cap formation by using a nucleoside triphosphate binding assay. Incubation of virion with [α-32P]GTP resulted in labeling of an 89-kDa protein that had not previously been identified in purified virus preparations. Interestingly this protein also covalently bound UTP and ATP, which is not a property of the known guanylyltransferases. RDV particles catalyzed GTP-PPi, dGTP-PPi, ATP-PPi, and UTP-PPiexchange reactions. In SDS–polyacrylamide gel electrophoresis, the 89-kDa protein comigrated with the S5-coded protein, P5, which had been expressed by a baculovirus vector. Moreover, the labeled 89-kDa protein was precipitated by an antiserum against this recombinant RDV P5. Careful reinvestigation of purified virus particles by SDS–polyacrylamide gel electrophoresis and Western blotting analyses showed that they contained a small amount of P5 (<0.5% of the total protein) within the core. These results may suggest that the minor core protein of RDV, which is coded by S5, is a candidate guanylyltransferase, although the biological significance of its ATP and UTP binding activities remains largely unknown
Restriction of HIV-1 (Subtype B) Replication at the Entry Step in Rhesus Macaque Cells

AbstractHuman immunodeficiency virus type 1 (HIV-1) is restricted for replication in rhesus macaque cells and does not establish infection in this species. The block to productive infection of macaque peripheral blood mononuclear cells (PBMC) in culture was investigated. A chimeric virus SHIV containing HIV-1tat, rev,andenvand all other genes from a simian immunodeficiency virus clone pathogenic in macaques (i.e., SIVmac239) replicated efficiently in macaque PBMC. Thus, the attachment step, involving interaction of the HIV-1envglycoprotein with the cell surface CD4 receptor, is not blocked. Analysis of uptake of HIV-1 particles in these cells revealed a small reduction in virion entry; however, viral DNA synthesis, measured by PCR amplification, was greatly reduced. Taken together, these results indicate that the block to HIV-1 (subtype B) replication in rhesus macaque cells involves release of the virion core into the cytoplasm and/or a step immediately prior to initiation of reverse transcription. Further studies are required to characterize this block through identification of species-specific cellular proteins that interact with HIV-1 proteins in the early phase of viral replication
Recruitment during Infectious Mononucleosis of CD3+CD4+CD8+Virus-Specific Cytotoxic T Cells Which Recognise Epstein–Barr Virus Lytic Antigen BHRF1

AbstractEpstein–Barr virus (EBV) is the aetiological agent of infectious mononucleosis (IM) which is a common sequel to primary EBV infection. Thereafter, the virus is maintained as a lifetime latent infection. Although the proteins expressed during the latent EBV infection provide a rich source of immunogenic epitopes, very little is known about cytotoxic T lymphocyte (CTL) control of primary EBV infection. The present report is based on an analysis of CTL clones derived from a patient suffering from acute IM. An intriguing feature of six CTL clones that displayed an HLA-restricted pattern of cell lysis was their initial coexpression of the T cell markers CD3, CD4, and CD8. Detailed analysis of one of these clones, which was restricted through the class II MHC antigen DR2, revealed reactivity with an epitope within the EBV lytic cycle early antigen, BHRF1, which corresponds to the C-terminal region of the protein (AGLTLSLLVICSYLFISRG) (residues 171–189). There have been no previously published reports describing a CTL response during acute IM directed against an EBV lytic antigen. Interestingly, the coexpression of CD4 and CD8 by these CTLs during acute IM suggests that CD3+CD4+CD8+cortical thymocytic precursor cells are recruited in order to overcome the EBV infection
Transforming Activity of the E6 Gene of HPV-11gt in NIH 3T3 and REF 52 Cells: Correlation with the Level of E6 Transcription

AbstractAmong human papillomavirus (HPV) types, clinical association with benign vs malignant lesions correlates with the ability of the corresponding oncogenes to transform cellsin vitro.However, even though HPV-11 is considered a low-risk type, we have reported previously that the E5a oncogene of HPV-11gt is capable of transforming NIH 3T3 cells in culture. In this study, we found that HPV-11gt E5a and E6 oncogenes have the ability to transform NIH 3T3 and the rat embryo fibroblast line REF 52. Cells were transfected independently with expression plasmids containing the HPV-11gt E5a or E6 oncogenes or both plasmids simultaneously to examine potential interactions. Cells containing these plasmids were phenotypically transformed and had an accelerated doubling time, loss of contact inhibition of growth, and loss of anchorage dependence for cell division. Independent cell lines containing the HPV-11gt E6 gene exhibited variable levels of phenotypic transformation that correlated with the HPV-11gt E6 gene content. The degree of phenotypic transformation could be increased by elevating the level of transcription of the E6 gene, indicating that there is a dose response effect for transformation in this system. These results suggest that increased expression of E6 may be an important factor in malignant progression of naturally occurring tumors
Mutation of Vaccinia Virus Gene G2R Causes Suppression of Gene A18R ts Mutants: Implications for Control of Transcription

AbstractThis report provides genetic evidence that two vaccinia virus genes, A18R and G2R, both of which affect the fidelity of viral transcriptionin vivo,interact with each other or act on a common biochemical pathway. Previous experiments with the antipoxviral drug isatin-β-thiosemicarbazone suggest that lethal mutation of gene G2R would compensate for mutations in gene A18R. We therefore tested the hypothesis that gene G2R is an extragenic suppressor of A18R mutations. First, we constructed a recombinant which contains both a G2R deletion mutation and an A18R temperature-sensitive mutation and found that this recombinant was viable. Second, we isolated both cold-sensitive and temperature-insensitive phenotypic revertants of A18R temperature-sensitive mutants and found in both cases that the revertants contained G2R mutations. In the case of the cold-sensitive revertants, we were able to prove that the cold-sensitive phenotype mapped to the G2R gene. Combined with the biochemical data on A18R and G2R, these results imply that the A18R and G2R genes interact with each other either directly or indirectly in a fashion which affects the fidelity of intermediate and late viral transcription
Amino Acid Tandem Repeats within a Late Viral Gene Define the Central Variable Region of African Swine Fever Virus

AbstractThe central variable region (CVR) of the African swine fever virus (ASFV) genome is contained within the 9-RL open reading frame (ORF). ORF 9-RL of the ASFV isolate Malawi Lil-20/1 predicts a protein of 614 amino acids with amino- and carboxy-terminal hydrophobic regions and a centrally located hydrophilic region. The CVR of the genome, located centrally within this ORF, is 372 bp and contains a 132-bp direct repeat. The translated CVR within ORF 9-RL contains 31 tandem tetramers, predominantly NADT, NANT, NVDT, and, in a few cases, CAST, GAST, or CADT.In vitrotranslation of 9-RL yielded a 94-kDa protein that was strongly reactive with convalescent pig serum while monospecific 9-RL antiserum identified a late viral protein of 94 kDa in ASFV-infected macrophages. The protein, detected by immunofluorescence staining with 9-RL antiserum, was distributed homogeneously throughout the cytoplasm of infected Vero cells. 9-RL protein size varied among different viral isolates and among cell-culture-adapted viruses. Protein size increased proportionately with the degree of cell culture adaptation and was directly correlated with the size of the CVR present within the ORF (300–500 bp). Analysis of the number and composition of tandem tetramers present within the CVR of a given ASFV isolate may prove useful for identifying and/or grouping ASFV isolates
N-Linked Glycosylation of Hepatitis B Surface Antigens Is Involved but Not Essential in the Assembly of Hepatitis Delta Virus

AbstractHepatitis delta virus (HDV) is a defective virus requiring the hepatitis B virus (HBV) to provide hepatitis B surface antigens as the envelope protein. The hepatitis B surface antigens are posttranslationally modified by N-linked glycosylation, and its significance in HDV assembly was investigated with a cotransfection system using human hepatoma cell line Huh-7. After the N-linked glycosylation of HBsAg was blocked by tunicamycin treatment, the packaging of HDV in the culture system could be suppressed to a level as low as 5–10% of the untreated control. The extent of inhibition correlated with the increased concentrations of tunicamycin. In contrast, the loss of HBsAg glycosylation did not affect the efficiency of assembly of HBV particles. When the N-linked glycosylation site of small HBsAg at amino acid 146 was mutated from asparagine to glutamine, the mutant HBsAg packaged only a modest amount of HDV particles. The quantity and kinetics of formation of HDV particles in culture system were reduced by the depletion of HBsAg glycosylation. Therefore HDV, similar to influenza and vesicular stomatitis viruses, depends on glycosylation of the envelope proteins as a signal for envelope protein maturation and for virion formation
Membrane Association of Influenza Virus Matrix Protein Does Not Require Specific Hydrophobic Domains or the Viral Glycoproteins

AbstractThe matrix protein of influenza virus is a major structural component of the virion which is generally believed to bridge between the membrane envelope and the ribonucleocapsid core. To investigate the interaction of M1 with cellular membranes in the absence of other influenza proteins, we examined its distribution by subcellular fractionation after expression in HeLa cells. Approximately 81 to 88% of M1 protein, expressed without other viral proteins, was soluble, whereas the remaining 12 to 19% was tightly associated with membranes. Conditions known to release peripherally associated membrane proteins did not detach M1 proteins from isolated membranes, suggesting that the fraction of M1 bound to membranes behaves as an integral protein. Coexpression of M1 with hemagglutinin or neuraminidase did not alter the extent of membrane association of M1 protein, indicating that there is no strong interaction between M1 and the cytoplasmic tails of the viral glycoproteins. Additional attempts were made to identify membrane binding domains in M1 protein. Mutants constructed with mutations in the four hydrophobic regions thought to be responsible for membrane association still exhibited the same levels of membrane association as that observed with wild-type matrix protein. Therefore, specific hydrophobic domains are apparently not required for membrane binding
Retroviral Infection of Syrian Hamster BHK Cells Depends on Age and Susceptibility toward Sialidase

AbstractInfection with recombinant retroviruses is a standard method to efficiently manipulate murine or human cells genetically. Due to differences in glycosylation of the hamster homologue to the murine ecotropic receptor and the absence of an amphotropic receptor, murine retroviruses are unable to infect hamster cells. Here we describe an isolated cell clone of the Baby Hamster Kidney cell line, BHK-21, that can be successfully infected with ecotropic murine retroviruses. This finding prompted us to investigate the possibility of changing the infectability of other cell strains by manipulating the receptors of these cell linesin vitro.We found that treatment of other BHK cell clones with sialidase fromC. Perfringensmakes these cell clones also permissive to murine ecotropic retroviruses. Long term cultivation of three tested cell clones increased this susceptibility. Although the resulting infectants show a higher rate of infectability, they still require the manipulation with sialidase for this superinfection to be efficient
The Product of Maize Streak Virus ORF V1 Is Associated with Secondary Plasmodesmata and Is First Detected with the Onset of Viral Lesions

AbstractWe have used a polyclonal antiserum derived from a bacterially expressed viral fusion protein to investigate the expression and subcellular localisation of the maize streak virus V1 product (PV1). Western blot analysis of agroinfected tissue showed that PV1 was detectable from 10 days postinoculation, coinciding with the first appearance of chlorotic viral lesions. The viral protein was only detectable in cell wall fractions of plant protein extracts. PV1 migrated with an apparent size of 14 kDa on SDS–PAGE, larger than the 10.9 kDa predicted from the amino acid sequence and therefore suggestive of posttranslational modification. Immunogold labelling located PV1 to the cell walls within lesion tissue and demonstrated a close association between the viral protein and secondary plasmodesmata. These results are consistent with the V1 product of MSV playing a role in the cell-to-cell movement of the virus in infected plants
Overexpression of the Herpes Simplex Virus Type 1 Tegument Protein VP22 Increases Its Incorporation into Virus Particles

AbstractThe tegument of herpes simplex virus type 1 (HSV-1) virus particles is a complex assemblage of virus proteins whose relative proportions within virions are essentially constant for a particular strain of virus. To examine the processes controlling incorporation into the tegument, we constructed a HSV-1 recombinant that expresses two copies of gene UL49, which encodes the major tegument protein VP22. One copy specifies the unmodified form of VP22 under the control of the native promoter while the second expresses an epitope-tagged version of the protein via the human cytomegalovirus immediate early promoter. In cells infected with the recombinant virus, the overall levels of VP22 synthesized were about fivefold higher than those for wild-type virus, due to the high levels of expression of tagged protein. Analysis of virus particles revealed that the amount of VP22 in the tegument was approximately two- to threefold higher in recombinant virions and L-particles than in particles produced by wild-type virus. These results provide the first evidence that, for certain proteins, the level of polypeptide synthesis can act as a controlling factor for the amount of protein incorporated into tegument
Host Range Restriction of Parainfluenza Virus Growth Occurs at the Level of Virus Genome Replication

AbstractTo illuminate the molecular basis for host range restriction of parainfluenza virus replication, we have examined the types of virus macromolecules produced during abortive infection of nonpermissive MDBK cells with human parainfluenza virus type 1 (hPIV1). While these cells do not support production of hPIV1 virus, they can be infected by hPIV1 as evidenced by accumulation of intracellular viral NP and HN proteins. HPIV1 is also able to drive transcription of a synthetic analog of Sendai virus (SV) genome RNA transfected into virus-infected MDBK cells. In contrast to transcription, hPIV1 genome replication does not occur in MDBK cells. Intracellular full-length genome RNA was detected only in trace amounts 2 days after infection, and was undetectable 4 days after infection. Full-length antigenome (+) sense RNA was not detectable. Nucleocapsid complexes failed to accumulate in the cytoplasm of nonpermissive cells, and no detectable nucleocapsids were released into the medium as virus particles. The data indicate that defective vRNA synthesis and/or nucleocapsid formation is responsible for the inability of hPIV1 to grow in MDBK cells. Our data also show that hPIV1 is capable of providing all helper functions for packaging SV synthetic genome analogs into infectious particles, but these SV-specific RNAs encapsidated with hPIV1 proteins are in turn not replicated by SV proteins. These results suggest that functional protein–protein interactions between parainfluenza virus strains have more stringent requirements than do protein–RNA interactions
A Conserved Region of Unknown Function Participates in the Recognition of E2F Family Members by the Adenovirus E4 ORF 6/7 Protein

AbstractE2F DNA-binding activityin vivois due to heterodimer formation between members of the E2F and DP transcription factor families. The ability of these heterodimers to serve as transcriptional regulators is modulated by complex formation with additional proteins such as the products of the retinoblastoma gene and the adenovirus E4 ORF 6/7. Each of the E2F family members cloned to date contains a highly conserved region of unknown function, termed the marked box, which lies between their DNA binding and transactivation domains. Mutational analysis showed that the marked box contributed to the recognition of E2F family members by the E4 ORF 6/7 proteinin vitroandin vivo
Protein–Protein Interactions between Epstein–Barr Virus Nuclear Antigen-LP and Cellular Gene Products: Binding of 70-Kilodalton Heat Shock Proteins

AbstractThe EBNA-LP protein encoded by the open reading frame in the leader exons of the Epstein–Barr nuclear antigen messages is essential for efficient immortalization of B lymphocytes. Protein–protein interaction studies using affinity precipitation of proteins from [35S]methionine-labeled cell lysates and bacterially expressed maltose binding protein EBNA-LP fusions were performed. A cellular 68/72-kDa doublet protein was detected. This banding pattern was shown to be identical to that obtained in affinity precipitations with fusions of glutathione–S-transferase and Sp1 (a basal transcription factor). For both EBNA-LP and Sp1 the specific interacting cellular proteins have been identified as heat shock proteins (HSP) 72/73. Affinity precipitation of HSP 72/73 with deletion mutants of EBNA-LP maps the interaction domain on EBNA-LP to exon Y2 which is required for immortalization. Immunoprecipitation of EBNA-LP from EBV-positive lymphoblastoid cell lines coprecipitated the HSP 72/73 proteins, indicating that the interaction occursin vivoas well asin vitro.The association of HSPs with a widening range of nuclear proteins involved in gene expression and proliferation control now includes Sp1 and EBNA-LP and suggests that there is a central role for molecular chaperones in these processes
The “Putative” Leucine Zipper Region of Murine Leukemia Virus Transmembrane Protein (P15e) Is Essential for Viral Infectivity

AbstractIn order to determine the role of the putative leucine zipper region of murine leukemia virus (MLV) transmembrane protein p15E, nine mutations in this region were introduced by site-directed mutagenesis. None of these mutations affected the expression or transport of the envelope protein or incorporation into virions. The mutants were analyzed for their ability to infect NIH3T3 cells and to induce cell fusion in a rat XC cell fusion assay. Mutations removing the charge of the hydrophilic residues reduced infectivity in NIH3T3 cells but had either no effect or a minor effect on envelope-induced XC cell fusion. Six mutations of hydrophobic residues of the putative leucine zipper region were constructed; four completely abolished the ability to infect NIH3T3 cells and these mutant envelopes were also unable to induce cell fusion in the XC cell fusion assay. These data demonstrate the absolute requirement for the putative leucine zipper region for both fusion and infection of MLV
Proteolytically Active 2A Proteinase of Human Rhinovirus 2 Is Toxic forSaccharomyces cerevisiaebut Does Not Cleave the Homologues of eIF-4γin Vivoorin Vitro

AbstractDuring the replication of rhino- and enteroviruses, the translation initiation factor eIF-4γ is specifically cleaved by the virally encoded 2A proteinase. This cleavage has been proposed to lead to the inability of the host cell to translate its own capped mRNA and to stimulate internal initiation of protein synthesis from the viral mRNA. However, a direct causal relationship between these effects and 2A proteinase-mediated cleavage of eIF-4γ has remained difficult to prove, mainly because of the toxicity of the 2A proteinase in mammalian expression systems. As an alternative approach, we placed the cDNA sequences for the human rhinovirus 2 2A proteinase and two mutants defective in proteolytic activity under the control of an inducible yeastGal1-10promoter and stably integrated them into the yeast genome. Induction of the wild-type enzyme led to changes in cellular morphology, an inhibition of cell division activity, and finally to cell death. As the yeast homologues of mammalian eIF-4γ, p150 and p130, were shown to be refractory to cleavage by human rhinovirus 2A proteinase bothin vivoandin vitroand the rate of protein synthesis was unaffected, the toxicity of the 2A proteinase toward budding yeast must be due to its interaction with at least one other cellular protein essential for viability