pinecone/core-2020-05-10-deduplication huggingface dataset:
Repression of p53 Transcriptional Activity by the HPV E7 Proteins

AbstractThe major transforming protein of human papillomaviruses (HPVs) is encoded by the E7 gene. This protein cooperates with activated oncogenes to transform primary rodent cells and with the viral E6 gene to immortalize primary human keratinocytes. Numerous cellular targets of HPV E7 have now been identified including pRb, p107, cyclin A, TATA box binding protein (TBP), and members of the AP-1 transcription factor family. As with Adenovirus E1a, many of these interactions are important for the ability of E7 to transform cells. Recent studies have demonstrated that Adenovirus E1a can also inhibit the transcriptional activity of the cellular tumor suppressor protein, p53. We have performed a series of analyses to determine whether HPV E7 proteins share this characteristic. We show that HPV E7 proteins derived from both benign and tumor-associated HPV types are able to inhibit p53 transcriptional activity. Mutational analysis of the HPV-16 E7 protein reveals that a key domain involved in mediating this activity is the casein kinase II (CKII) recognition site, which has been shown to modulate E7 binding to TBP. We further show that E7 does not bind to p53 directly, but will do so in the presence of exogenously added TBP and that this binding is increased following CKII phosphorylation. These results suggest that the E7–TBP interaction may be responsible for inhibiting p53 transcriptional activity
Natural Endogenous Reverse Transcription of Simian Immunodeficiency Virus

AbstractIt has been demonstrated that human immunodeficiency virus type 1 (HIV-1) virions are biochemically active particles, within which reverse transcription can take place even in physiological microenvironments. This process has been termed “natural endogenous reverse transcription” (NERT). In this report, we demonstrate that purified virions of simian immunodeficiency virus (SIV) also contain virus-specific DNA, which resulted from partial reverse transcription. Further, viral DNA synthesis could be initiated in SIV virions in the presence of polyamines and deoxyribonucleoside triphosphates (dNTPs), at physiological concentrations. The viral infectivity upon initially quiescent cells was significantly increased, when the levels of intravirion reverse transcripts were modulated. These data suggest that NERT of SIV may play an important role for SIV pathogenesis and transmission. In contrast to HIV-1, these hypotheses may be further directly investigated byin vivomodel systems
Primary Infections with HIV-1 of Women and Their Offspring in Rwanda: Findings of Heterogeneity at Seroconversion, Coinfection, and Recombinants of HIV-1 Subtypes A and C

AbstractVariation in HIV-1 genomic RNA was studied in seroconversion samples from mother–child pairs from a Rwandan cohort. The mothers (n= 8) were heterosexually infected and their children (n= 6) were vertically infected by breast milk. Five of the children seroconverted within the same 3-month period as did their mothers. Highly homogeneous subtype A V3 and p17gagsequence populations were observed in three mother–child pairs, one of the two nontransmitting mothers, and one child (mean nucleotide distances 0 to 0.9%). Heterogeneous populations of subtype A V3 and p17gagsequences were found in one mother and a mother–child pair (1.4 to 2.8% for V3, 1.0 to 1.9% for p17). The second nontransmitting mother was infected with a heterogeneous AV1-V3/Cp17-p24recombinant virus population (3.8% for V3, 2.4% for p17). Finally, in one woman subtype C V3 sequences were observed, in addition to highly homogeneous subtype A V3 and p17gagsequence populations, also found in the child. Coexistence of subtype AV1-V3and CV1-V3envsequences in the mother was confirmed in a follow-up sample. Thegaggene of both the maternal and the child's virus population represented an A/C recombinant sequence (Ap17/Cp24). An infection with subtype CV1-V3/p17-p24was found upon testing of three additional participants of the mother–child cohort, indicating that subtype C is present in Rwanda. In conclusion, heterogeneity, coinfection, and intersubtype recombinants are not uncommon in primary HIV-1 infections in Rwanda
Structure–Function Analysis of Coxsackie B3 Virus Protein 2B

AbstractExpression of poliovirus protein 2B in mammalian cells inhibits protein secretion and increases the susceptibility of the cells to hygromycin B, consistent with the increase in plasma membrane permeability seen during poliovirus infection (J. R. Doedens and K. Kirkegaard,EMBO J.14, 894–907, 1995). We report here that expression of protein 2B of the closely related coxsackie B3 virus (CBV3) leads to the same biochemical alterations. Analysis of several mutant CBV3 2B proteins that contain mutations in a predicted cationic amphipathic α-helix (F. J. M. van Kuppeveld, J. M. D. Galama, J. Zoll, P. J. J. C. van den Hurk, and W. J. G. Melchers,J. Virol.70, 3876–3886, 1996) demonstrated that the integrity of this domain is crucial for both biochemical functions of 2B. Mutations in a second hydrophobic domain (F. J. M. van Kuppeveld, J. M. D. Galama, J. Zoll, and W. J. G. Melchers,J. Virol.69, 7782–7790, 1995), on the other hand, are more disruptive to the ability of CBV3 2B to inhibit protein secretion than to increase membrane permeability. Therefore, inhibition of protein secretion is not merely a consequence of the membrane changes that increase uptake of hygromycin B. The existence of mutations that interfere with virus growth but do not impair the ability of 2B to inhibit protein secretion or increase membrane permeability argues for additional functions of protein 2B
Isolation of a gp20-Complex and Its Role inin VitroAssembly of both Prohead and Core of Bacteriophage T4

AbstractThe product of gene 20 (gp20) in bacteriophage T4 forms the proximal vertex of the head. It has been suggested that gp20-rich fractions derived from the proheads can initiate core assemblyin vitroand that gp20 plays an important role in prohead and core assembly. However, the gp20 isolated from proheads or overproducing cells harboring gene 20 did not workin vitro,owing to a strong tendency to aggregate. Native gp20 was purified from T4-infectedEscherichia coli hdB3-1cells, since it was shown that gp20 might not associate with membrane in this infection. Isolated gp20 is associated with two other proteins in a gp20-complex, composed of a connector and a neck joined to six fibers. The gp20-complex is also produced in T4 infection ofE. coli groEL.Moreover, the complex can efficiently induce prohead and core assembly and is very stable
Receptor Specificity of Influenza A Viruses Correlates with the Agglutination of Erythrocytes from Different Animal Species

AbstractDespite their uniform ability to bind to oligosaccharide-containing terminal sialic acids, influenza A viruses show differences in receptor specificity. To test whether agglutination of erythrocytes from different animal species could be used to assess the receptor specificity of influenza A viruses, we determined the agglutinating activities of a range of virus strains, including those with known receptor specificities, using erythrocytes from seven animal species. All equine and avian viruses, including those known to recognizeN-acetyl andN-glycolyl sialic acid linked to galactose by the α2,3 linkage (NeuAcα2,3Gal and NeuGcα2,3Gal), agglutinated erythrocytes from all of the animal species tested (chickens, ducks, guinea pigs, humans, sheep, horses, and cows). The human viruses, including those known to preferentially recognize NeuAcα2,6Gal, agglutinated all but the horse and cow erythrocytes. Fluorescence-activated cell sorting analysis of erythrocytes using linkage-specific lectins [Sambucus nigraagglutinin for sialic acid (SA)α2,6Gal andMaackia amurensisagglutinin for SAα2,3Gal] showed that both cow and horse erythrocytes contain a large amount of SAα2,3Gal-, but virtually no SA2,6Gal-specific lectin-reactive oligosaccharides on the cell surface, while human and chicken erythrocytes contained both types of oligosaccharides. Considering that the majority (>93%) of sialic acid in horse and cow erythrocytes is of theN-glycolyl type, our results suggest that viruses able to agglutinate these erythrocytes (i.e., avian and equine viruses) recognize NeuGcα2,3Gal. These findings also show that agglutinating assays with erythrocytes from different animal species would be useful in characterizing the receptor specificity of influenza A viruses
Analysis of the 3′ Terminal Sequence Recognized by the Rift Valley Fever Virus Transcription Complex in Its Ambisense S Segment

AbstractA reconstituted transcription system composed of the Rift Valley fever phlebovirus (Bunyaviridae family) proteins L and N expressed via recombinant vaccinia viruses and an S-like model RNA containing the CAT gene in the antisense orientation, has been described previously by Lopezet al.(J. Virol.,1995, 69, 3972–3979). We extended the use of thisin vivosystem to determine the sequence at the 3′ end of the ambisense S segment recognized by the transcription complex. A mutational analysis of the sequences at the 3′ end of the S-like genomic or antigenomic RNA was undertaken. The data indicated that the minimal sequence required for transcription resides in the 13 first 3′ nucleotides of the genomic or antigenomic RNA. In these sequences, two regions appeared crucial: the bases at positions 3 to 8 and the purine at position 13. In addition, the terminal repeat ...GU could be deleted without affecting significantly the template activity of the RNA. These data support the prime and realign mechanism proposed recently for Bunya- and Arenaviruse
In Vivoandin VitroEvidence for an Anti-Rho Activity Induced by the Phage P4 Polarity Suppressor Protein Psu

AbstractThe polarity suppression (Psu) protein of bacteriophage P4 causes suppression of transcriptional polarity inEscherichia coliby overcoming Rho termination factor activity. Two newpsumutants defective in polarity suppression are described. Thepsu5mutation deletes codons 95–98 from about the middle of the gene, and the mutant protein is inactive. Thepsu6mutation changes Phe169 to Val and encodes a temperature-sensitive protein. Constitutive overexpression ofpsu+from a plasmid prevents colony formation, but overexpression of mutant genes (psu5, psu6) does not, suggesting that Psu disturbs essential host function(s). Rho protein synthesis is enhanced several-fold in cells containing wild-type Psu, due to readthrough at therhoattenuator, while the physical stability of Rho is maintained. As a consequence, Psu-producing cells accumulate significantly more Rho than normal cells, reminiscent of termination-defectiverhomutants. The polarity suppression activity induced by Psu is demonstratedin vitroby the efficient readthrough of Rho-dependent terminators λ tR1and TIS2during coupled transcription–translation. Purified Rho protein restores termination at TIS2when added to Psu-containing reactions but NusG does not. The data support the hypothesis that Psu has or elicits an anti-Rho function
Characterization of Proteins Binding to the ZII Element in the Epstein–Barr Virus BZLF1 Promoter: Transactivation by ATF1

AbstractPrevious studies have shown that the ZII element in the BZLF1 promoter (P1) is responsive to TPA and anti-immunoglobulin induction. In this report, we have studied the DNA/protein complexes formed when ZII is used as a binding site. Twelve distinct DNA/protein complexes were seen in mobility shift experiments using Akata cell nuclear extracts and radiolabeled ZII. Eleven of these complexes were also formed when either BJAB or Raji cell nuclear extracts were used in the binding reaction. Six DNA/protein complexes were affected by mutations in the core TGACATCA motif of ZII which abolish responsiveness to TPA, anti-immunoglobulin treatment, and HHV6 transactivation. The relative sizes of the proteins in the DNA/protein complexes were determined by UV crosslinking. Four distinct specific binding proteins affected by core mutations in ZII were identified as ATFa, ATF1, ATF2, and c-jun. Overexpression of ATF1 in cotransfection experiments caused transactivation of the wild-type P1 promoter but had no effect on a promoter containing a mutant ZII element. An ATF1 mutant with a deleted DNA binding domain failed to transactivate P1. Overexpression of c-jun, ATFa, or ATF2 had no effect on the wild-type or mutant P1 promoter. Our results suggest that ATF1 interacts with the ZII element and may be involved in Epstein–Barr virus reactivation
PCR-Directed Formation of Viral Hybridsin Vitro

AbstractWhen constructing viruses that have desired hybrid phenotypes, anticipated difficulties include the nonviability of many, possibly most, of the hybrid genomes that can be constructed by incorporation of DNA fragments. Therefore, many different hybrid genomes may have to be constructed in order to find one that is viable. To perform this combinatorial work in a single experiment, we have used bacteriophage T7-infected cell extracts to transfer DNAin vitro.In an extract, we have incubated T7 DNA, together with DNA obtained by polymerase chain reaction (PCR) amplification of the gene (gene 17) for the tail fiber of the T7-related bacteriophage, T3. Afterin vitropackaging of DNA in the extract, hybrid progeny bacteriophage were detected by probing with a T3-specific oligonucleotide; hybrids are found at a frequency of 0.1%. By determination of the nucleotide sequence of the entire gene 17 of 14 independently isolated hybrids, both right and left ends of the PCR fragment are found to be truncated in all hybrids. For all 14 hybrids, the right end is in the same location; the left end is found at 3 different locations. The nonrandom location of the ends is explained by selection among different inserts for viability; that is, most of the hybrid genomes are nonviable. Some hybrids acquire from T3 the desirable phenotype of nonadherence to agarose gels during agarose gel electrophoresis
Differences in the UV-Crosslinking Patterns of the Poliovirus 5′-Untranslated Region with Cell Proteins from Poliovirus-Susceptible and -Resistant Tissues

AbstractThe restricted tissue tropism observed in poliovirus infection is not governed solely by the expression of the poliovirus receptor (PVR) gene, but might be controlled at stages beyond virus entry, such as translation, replication, or assembly. Translation of poliovirus RNA by a cap-independent mechanism requires interactions of the 5′-untranslated region (5′UTR) with cell proteins. To determine whether the patterns of these interacting proteins differ in HeLa cells and permissive and nonpermissive tissues, UV-crosslinking assays using the poliovirus 5′UTR and tissue extracts from PVR transgenic mice were performed. The results indicate a correlation between the presence of a 97-kDa UV-crosslinked protein and permissivity to poliovirus infection. Acquired poliovirus susceptibility inin vitro-cultured kidney cells also correlates with the presence of a 97-kDa crosslinked band. The interaction of the 97-kDa protein from HeLa cells and mouse brain with the poliovirus 5′UTR is stable and specific. Whether the 97-kDa protein plays a role in poliovirus translation and tissue susceptibility remains to be determined
Poxvirus-Based Japanese Encephalitis Vaccine Candidates Induce JE Virus-Specific CD8+Cytotoxic T Lymphocytes in Mice

AbstractRecombinant Japanese encephalitis (JE) vaccine candidates based on a highly attenuated vaccinia virus (NYVAC-JEV) and a canarypox virus (ALVAC-JEV) were evaluated for their ability to induce specific antibodies and cytotoxic T lymphocytes (CTLs) in mice. Six- to eight-week-old male Balb/c mice that received one or two intraperitoneal inoculations with these JE vaccine candidates at a dose of 1 × 107PFU per mouse produced neutralizing antibody and antibodies to the envelope (E) and nonstructural 1 (NS1) proteins as determined by radioimmunoprecipitation. Immunization with either of these vaccine candidates also induced JE virus-specific T lymphocytes that proliferated in response to stimulation with infectious virus and/or noninfectious viral antigens. Mice maintained detectable levels of neutralizing antibody and JE virus-specific memory T cells for at least 6 months after immunization with NYVAC-JEV and for 4 months after immunization with ALVAC-JEV. Cells induced to proliferate after stimulation with live virus contained specific CD8+CTLs that lysed primary Balb/c mouse kidney cells infected with JE virus and P815 mastocytoma cells infected with a recombinant vaccinia virus expressing the premembrane (prM), E, and NS1 proteins. These CTLs also lysed P815 cells infected with vaccinia recombinants expressing prM and E, and those expressing E and NS1, but did not lyse P815 cells infected with a recombinant virus expressing only NS1, indicating that the CTLs mainly recognized E, but did not recognize NS1. These results demonstrate that both recombinant JE vaccines, NYVAC-JEV and ALVAC-JEV, induce JE virus-specific antibody and CTLs in mice
Molecular Characterization and Baculovirus Expression of the Glycoprotein B of a Seal Herpesvirus (Phocid Herpesvirus-1)

AbstractA glycoprotein B (gB) gene homologue was identified in a 5.4-kbBamHI genomic fragment of the phocid herpesvirus type-1 (PhHV-1) which represents a widespread and important pathogen of pinnipeds. Sequence analysis revealed a gB-specific open-reading frame comprising 881 amino acids. Phylogenetic analysis gave evidence for a close evolutionary relationship between PhHV-1 and members of theVaricellovirusgenus of the α-Herpesvirinaeand canid herpesvirus in particular. In PhHV-1-infected Crandell feline kidney cells gB is expressed as a 113-kDa glycosylated molecule which is proteolytically cleaved into at least two fragments of 67 and 53–59 kDa apparently forming disulfide-linked heterodimers of 140 kDa. Cell surface expression of PhHV-1 gB was confirmed by FACS analysis. Thus, synthesis and processing of the gB protein of PhHV-1 follows a pattern also observed in otherVaricelloviruses.Since the gB protein of herpesviruses, expressed in the baculovirus system, has been shown to be a suitable target for vaccine design, we used this system for expression of PhHV-1 gB. Recombinant (rec) baculovirus-expressed gB was identified as a 105-kDa glycosylated molecule. Proteolytic cleavage into fragments of 62 and 52 kDa was markedly delayed compared to wild-type (wt) gB. Wt and rec gB harbored endoglycosidase H (precursor)- as well as N-glycosidase F-sensitive N-glycans (proteolytic fragments). Baculovirus-expressed gB appeared to be antigenically authentic, since it was recognized in radioimmunoprecipitation and immune peroxidase monolayer assays by PhHV-1-neutralizing seal sera and by gB-specific neutralizing murine monoclonal antibodies. Furthermore, PhHV-1-neutralizing antibodies were induced in mice following immunization with baculovirus-expressed gB, indicating its suitability for incorporation in a candidate vaccine for seals
Analysis of Mutations within the Cytoplasmic Domain of the Moloney Murine Leukemia Virus Transmembrane Protein

AbstractThe role of the cytoplasmic tail of the Moloney murine leukemia virus transmembrane protein in the regulation of syncytia was examined. Three mutations within the cytoplasmic tail were studied. Linker-insertionin7705-12a is within the viral-associated cytoplasmic tail, linker-insertionin7748-12a is within the R peptide, and a third mutation expresses TM lacking the R peptide (Env R−). The Env R−construct was nonviable in Rat1 cells, however, rapidly reverted to a form containing the R peptide when passaged in NIH/3T3 cells.in7705-12a was temperature-sensitive in Rat1 cells, as previously characterized, but was viable at either temperature in NIH/3T3 cells.in7748-12a was comparable with wild-type M-MuLV. The ability of theenvconstructs to form large multinucleated syncytia with NIH/3T3 and XC cells were examined using transient expression assays, eliminating reversion events due to viral passage and reverse transcription. The Env R−constructs formed syncytia with NIH/3T3 cells.in7705-12a displays enhanced proteolytic cleavage of the R peptide. Neither linker-insertion mutationin7705-12a orin7748-12a activated fusion with NIH/3T3, despite the abundance of processed TM within7705-12a. All three mutants were fusion competent with Rat XC cells, even in the absence of any cleavage of the R peptide. These results provide insights regarding steric and the temporal affects of cleavage of the R peptide and the assembly of a fusion competent oligomer
Characterization of a Unique OpMNPV-Specific Early Gene Not Required for Viral Infection in Tissue Culture

Abstractopep-2is anOrgyia pseudotsugatamulticapsid nucleopolyhedrovirus (OpMNPV) early gene in theie1–ie2gene region for which there is no homolog in either the archetype virus,Autographa californicaMNPV, orBombyx moriNPV.opep-2is transcribed immediately upon infection as three mRNAs which initiate from a early gene motif (TATA-N27-CAGT). The expression of multiple transcripts at very early times postinfection has only been previously described for the baculovirus early geneie1,which produces spliced mRNAs. However, distinct fromie1,the multiple mRNAs ofopep-2are due to multiple termination sites and not splicing. Western blot analysis of steady-state levels of OPEP-2 showed that in OpMNPV-infected Ld652Y cells maximum levels are obtained at 8–12 hr postinfection (p.i.) prior to DNA replication. By 48 hr p.i. OPEP-2 is shut off and is undetectable. To aid in elucidating the function of this OpMNPV-specific gene anopep-2deletion mutant was generated and was compared to wild-type virus to determine if its absence affects viral growth in Ld652Y tissue culture cells
Assemblin Homolog of Herpes Simplex Virus Type 1 Retains Proteolytic Activity When Expressed as a Recombinant Two-Chain Enzyme

AbstractThe herpes simplex virus type 1 (HSV) maturational proteinase is synthesized as a precursor that undergoes two autoproteolytic cleavages; one at its (M)aturational site, which eliminates its carboxyl “tail,” and a second at its (R)elease site, which separates the amino proteolytic half of the precursor from its nonproteolytic carboxyl half. In cytomegalovirus (CMV) the proteolytic half of the precursor, called assemblin, undergoes a third cleavage at an (I)nternal site that converts it from a single-chain to a two-chain enzyme that retains activity. The HSV assemblin homolog has no I site and therefore does not form a counterpart two-chain enzyme. In the work reported here we have cloned and expressed HSV sequences that encode mimics of the Anand Acsubunits of two-chain CMV assemblin. We show that when these HSV sequences are coexpressed in eukaryotic cells, the resulting subunits associate spontaneously to form an active two-chain enzyme. We also show that the two-chain HSV enzyme, like the natural one-chain form, retains its marked preference for HSV over CMV substrates, and that intertypic recombinant two-chain assemblin (e.g., HSV An/CMV Ac) does not form because the cross-species subunits do not interact. We conclude from these results that (i) there are not intrinsic structural differences in the HSV assemblin homolog that preclude its functioning as a CMV-like two-chain enzyme, (ii) the substrate selectivity shown by the single-chain HSV enzyme was not noticeably relaxed in the HSV two-chain mimic, and (iii) the interactive domains, through which the Anand Acportions of the single-chain enzymes associate, differ between HSV and CMV