pinecone/core-2020-05-10-deduplication huggingface dataset:
The Role of the AcMNPV25KGene, “FP25,” in Baculoviruspolhandp10Expression

AbstractA previous study showed that anAutographa californicamulticapsid nuclear polyhedrosis virus (AcMNPV)25Kmutant produced less polyhedrin protein than wild-type (Jarviset al., J. Virol.66, 6903–6911, 1992). In this study, the role of the25Kgene product (AcMNPV ORF 61) in baculovirus gene expression was further investigated. Five different viral25Kmutants expressed lower levels of polyhedrin protein and less CAT activity under the control of thepolhpromoter compared to wild-type.PolhRNA was equally stable in wild-type and mutant virus-infected cells while the rate ofpolhtranscription was significantly reduced in mutant-infected cells. In comparison, steady-state levels ofp10RNA were not reduced in25Kmutant-infected cells, indicating that the reduction inpolhRNA did not reflect a general effect on very late gene transcription. Expression ofie-1,which also appears to influencepolhexpression (Choi and Guarino,Virology209, 90–98, 1995), was not influenced by25Kmutation. These results show that the 25K protein is important for maintaining optimal levels ofpolhtranscription by a mechanism that does not involve maintainingie-1expression
The Influence of AUG Codons in the Hepatitis C Virus 5′ Nontranslated Region on Translation and Mapping of the Translation Initiation Window

AbstractThe initiation of translation of hepatitis C virus (HCV) is cap-independent and mediated by an internal ribosome entry site (IRES) that is located in the 5′ nontranslated region (5′ NTR) of the viral genome. This 5′ NTR is relatively long and folds into a complex structure involving multiple hairpins and a pseudoknot. Within the sequence encompassing the IRES there are several AUG triplets. Some of these AUG codons are conserved between HCV genotypes and the related pestiviruses. In this study the 5 AUG codons (positions 13, 32, 85, 96, and 215) that are present in the 5′ NTR of the HCV H-strain have been mutagenized to determine their influence on HCV cap-independent translation. The effect of these mutations on the expression of a chloramphenicol acetyl transferase (CAT) gene was tested in vaccinia virus vTF7-3 infected Hep2 cells transfected with plasmids for the expression of a monocistronic HCV 5′ NTR-CAT mRNA. Mutating the AUG codons at positions 13, 32, and 215 does not have a significant effect on CAT expression, inactivating the AUG codons at either position 85 or position 96 severely impaired IRES function. To determine whether ribosomes scan the RNA to select the initiation site, AUG codons were inserted up- and downstream of the authentic HCV polyprotein translation initiation codon (position 342). Analysis of these mutants has revealed that the ribosome is unable to use an AUG codon that is placed either 7 nucleotides upstream or 8 nucleotides downstream of the inactivated AUG at position 342. These results indicate that when scanning is involved in the recognition of the translation initiating AUG, it is limited to a narrow region between nucleotides 335 and 350
Characterization of a Novel Baboon Virus Closely Resembling Human T-Cell Leukemia Virus

AbstractWe report the isolation of a virus from a baboon imported from Kenya and the analysis of the nucleotide sequence of theenvgene. Comparison of the complete nucleotide sequence of theenvgene of different HTLV-1 strains and the baboon T-cell leukemia virus (designated BTLV) indicated similarities ranging from 92.5 to 97.4%. In contrast, only 89.1% similarity was observed between the BTLVenvsequence and that of simian T-cell leukemia virus (PtM3). The sequences corresponding to the glycosylation sites, endoproteolytic processing site, and major immunological determinants were strictly conserved between BTLV and HTLV-1. To characterize the expressed protein we used a vaccinia expression system, which indicated that a protein of 62 kDa is encoded by the envelope gene. The protein acquired mostly high mannose modifications and was localized predominantly in the endoplasmic reticulum. A fraction of the protein was expressed at the cell surface, where it could induce membrane fusion of target cells. The existence of HTLV-1-like viruses in baboons indicates the potential risk of transmission of such virus from these nonhuman primates to humans, thus highlighting the need for specific screening for such viruses during xenotransplantation
Characterization of a Hemagglutinin-Specific Inhibitor of Influenza A Virus

AbstractA novel inhibitor of influenza virus growth in tissue culture was identified and characterized. This compound (BMY-27709) has an IC50of 3–8 μMfor A/WSN/33 virus growth in a multicycle replication assay and is active against all H1 and H2 subtype viruses tested. However, BMY-27709 was found to be inactive against H3 subtype viruses, as well as influenza B/Lee/40 virus. BMY-27709 was also found to act against H1 and H2 viruses early in infection, suggesting that the target for inhibition is the hemagglutinin protein. This was confirmed through the use of reassortant viruses and the isolation of a virus resistant to BMY-27709. The resistant virus isolated contained a phenylalanine to serine change at amino acid 110 of the HA2 subunit. That this single mutation was responsible for the acquisition of resistance to BMY-27709 was proven through reverse genetics, as transfectant virus containing only this change was shown to be resistant to BMY-27709, while the control virus without this mutation remained sensitive. BMY-27709 is able to inhibit virus-induced red blood cell hemolysis, suggesting that it blocks the membrane fusion function of hemagglutinin. These experiments further illustrate that the hemagglutinin protein of influenza virus is a viable target for the discovery and development of small molecule inhibitors of virus growth
Characterization of the Protein Product Encoded by a Splicing Variant of the Marek's Disease VirusEco-Q Gene (Meq)

AbstractIn the present study, we report the characterization of a 212-amino-acid polypeptide encoded by a splicing variant of the Marek's disease virusEco-Q gene (Meq). This protein, referred to as Meq-sp, contains the N-terminal 100 amino acids of Meq, which include part of Meq's DNA binding/dimerization domain, but lacks the transactivation domain of Meq. Thus, Meq-sp was examined for its ability to bind to DNA and act as a transactivator. Results indicated that while Meq and Meq-sp could both bind to the AP-1 binding site, the 110 C-terminal amino acid residues of Meq-sp lacked the ability to function as a transactivator when fused to the GAL4 (1-147) DNA binding motif. To investigate whether Meq-sp can interact with Meq or with c-jun, protein–protein and protein–DNA interactionsin vitrowere examined. Results showed that Meq-sp can associate with both Meq and c-jun and bind to the AP-1 site with a higher affinity as a heterodimer with c-jun. These results suggest that Meq-sp could compete with Meq for heterodimer formation with c-jun and dimer binding to DNA and possibly act as a transdominant negative regulator of Meq activityin vivo
Human Endogenous Retrovirus HC2 Is a New Member of the S71 Retroviral Subgroup with a Full-LengthpolGene

AbstractWe have isolated and characterized a new human endogenous provirus, which is closely related to the human retrovirus S71, but unlike S71 has a full-lengthpolgene. Two degenerate oligonucleotide primers based on highly conserved motifs within the active sites of two retroviral proteins (the protease and reverse transcriptase) were designed and used for PCR. An amplified product of 847 bp in length, which showed significant homology to protease and reverse transcriptase of several retroviruses, was used for high stringency hybridization with a human genomic library. The MuLV-related endogenous retrovirus sequence, designated HC2, was isolated and completely sequenced. HC2 is a provirus with completegagandpolgenes and a 3′ LTR; the 5′ LTR andenvgene are missing. Thegagandpolgenes appear complete, since they contain sequences homologous to the matrix protein, capsid protein, and nucleocapsid protein of gag and to the protease, reverse transcriptase, tether, RNase H, and integrase of pol. Phylogenetic analysis suggests that although HC2 and S71 are MuLV-related retroviruses, their characters are quite distinct, being placed outside of a clade containing most of the previously characterized MuLV-related retroviruses such as GaLV, FeLV, BaEV, and SSV/SSAV
Growth of Molluscum Contagiosum Virus in a Human Foreskin Xenograft Model

AbstractMolluscum contagiosum virus (MCV) is a common pathogen causing a troublesome skin condition in many immunocompetent individuals and a widespread, disfiguring affliction in many patients with AIDS. We have successfully infected human foreskin fragments with a patient-derived isolate of MCV. This was demonstrated by exposing the foreskin pieces to a patient lesion extract and implanting the tissue under the renal capsule of athymic mice. Light and electron microscopic examination of infected implants showed the presence of cytoplasmic inclusions containing typical poxvirus particles within 2–3 weeks of implantation. Replication of MCV was established by demonstrating that viable virus was required to produce the cytopathologic effects, and viral DNA replication was demonstrated by incorporation of bromodeoxyuridine into cytoplasmic inclusions. Four additional patient extracts (representing both described MCV types) were also used to successfully infect foreskin implants. A limited number of attempts to pass virus from one infected implant to another were not successful. This system is the most rapid and reproducible for growing MCV that has been reported to date
Identification of HTLV-1-Specific CTL Directed against Synthetic and Naturally Processed Peptides in HLA-B*3501 Transgenic Mice

AbstractPrevious studies of CTL responses to influenza peptides in HLA single transgenic mice resulted in the identification of at most one immunodominant epitope. Since HLA-B*3501 is known to present multiple HIV-1-specific T cell epitopes we tested the cellular immune response of HLA-B*3501 transgenic mice to synthetic HTLV-1 peptides mixed with the lipohexapeptideN-palmitoyl-S-[2,3-bis(palmitoyloxy)propyl]cysteinyl-seryl-lysyl-lysyl-lysyl-lysine, which is a biocompatible, Th-epitope-independent adjuvant. Eleven of 37 tested HLA-B*3501 binding peptides mounted a CTL response after threein vitrostimulations. The HLA-B*3501 affinity of peptides correlated with their ability to induce CTL in HLA-B*3501 transgenic mice. Seven peptides derived from env-gp46 (VPSPSSTPLL, VPSSSSTPL, YPSLALAPH, and YPSLALAPA), pol (QAFPQCTIL), gag-p19 (YPGRVNEIL), and tax (GAFLTNVPY) proteins induced peptide-specific CTL. Bulk CTL generated by four peptides derived from env-gp46 (SPPSTPLLY, VPSPSSTPLLY, and VPSPSSTPLL) and pol (QAFPQCTILQY) killed peptide-pulsed and recombinant vaccinia-infected target cells. The latter peptides therefore present T-cell epitopes and are vaccine candidates for our transgenic mouse model
Definition of the RRE Binding and Activation Domains of the Caprine Arthritis Encephalitis Virus Rev Protein

AbstractCaprine arthritis encephalitis virus (CAEV) is a lentivirus which is closely related by nucleotide sequence and biological properties to visna virus and is more distantly related to the human AIDS virus, HIV-1. Previous studies indicated that the CAEV Rev protein (Rev-C) functions as atrans-activator of mRNA cytoplasmic transport and expression. The function of Rev-C is mediated through an RNA element (RRE-C) present between nucleotides (nt) 7906 and 8110 in the CAEVenvgene. In this study, RNA/protein immunoprecipitation experiments were used to demonstrate that Rev-C binds directly to the 204-nt RRE-Cin vitro.Competition assays illustrate that this interaction is specific for the positive sense RRE-C RNA. Glutaraldehyde crosslinking studies demonstrate that the wildtype Rev-C protein can also form multimeric complexesin vitro.Deletions or amino acid alterations within the basic domain of Rev-C reduce affinity for the RRE and disrupt assembly of Rev-C multimersin vitro,indicating that this domain is involved in RRE binding and Rev multimer formation. Mutations within the leucine-rich domain of Rev-C do not greatly effect RRE-C binding or self-assembly. However, previous results demonstrate that some leucine-rich domain mutants are unable totrans-activate. These data are consistent with the hypothesis that the leucine domain is the effector domain of Rev-C
The Strain-Specificcis-Acting Element of Beet Curly Top Geminivirus DNA Replication Maps to the Directly Repeated Motif of theOri

AbstractStrains of beet curly top geminivirus (BCTV) possess distinctcis- andtrans-acting replication specificity elements which are not separately interchangeable among strains. Analysis of the replication competency of chimeric BCTV genomes, in which portions of the origin of DNA replication (ori) were derived from heterologous BCTV strains, have permitted identification of an essentialcis-acting element governing strain-specific replication in a subgroup II geminivirus. Our studies indicate that thecis-acting element responsible for strain-specific replication properties resides within the directly repeated motif of the BCTVori.Transient replication assays conducted in leaf disks and complementation experiments conducted in whole plants indicated that thetrans-acting replication specificity element, residing within the amino-terminal region of the C1 Rep protein, may recognize and replicate a chimeric BCTV genome containing a heterologousoriso long as all or portions of the core element of the directly repeated motif are derived from the same strain as the Rep protein. As Rep protein binding to the core element of the directly repeated motif has been demonstrated by others to be essential for replication of subgroup III geminiviruses, our results support the hypothesis that replication specificity of subgroup II viruses is governed by processes similar to that of subgroup III viruses. However, a secondcis-acting element of theori,which appears to contribute to subgroup III virus replication specificity, does not seem to be required for replication specificity among the subgroup II viruses examined. Nonetheless, a potential role for a secondcis-acting element in the BCTVoricontributing to maximal replication cannot be excluded
Inducible Gene Expression of the Human Immunodeficiency Virus LTR in a Replication-Incompetent Herpes Simplex Virus Vector

AbstractAlthough replication-incompetent herpes simplex virus (HSV) vectors have the capability to express foreign genes, successful development of these vectors for gene delivery would require that expression of the foreign gene be regulated. To investigate the feasibility of obtaining inducible expression of a foreign gene in such a vector, a replication-incompetent HSV vector, vd120/LTRβ, was developed that used the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) to express theEscherichia coli lacZgene. Examination oflacZexpression from the HIV-1 LTR in vd120/LTRβ-infected cells indicated that the LTR was active as a promoter under both replicating and nonreplicating conditions, although expression oflacZunder nonreplicating conditions was approximately 4-fold lower. In addition, the LTR expressedlacZin a manner distinct from that of well-characterized HSV-1 promoters of each temporal class. The effect of the HIV-1 regulatory protein Tat on expression from the LTR in vd120/LTRβ was examined by infection of two different HeLa-derived cell lines that constitutively expressed Tat, HL2/3, and HLtat. Compared to infection of HeLa cells,lacZexpression from vd120/LTRβ-infected HL2/3 and HLtat cells increased from 4- to 24-fold, depending on the multiplicity of vector infection. Sustained expression oflacZfrom the LTR in vd120/LTRβ-infected cells was not observed even in the continuous presence of Tat, although vector could be recovered for up to 5 days after infection. However, the amount of recoverable vector decreased during this time, suggesting that cellular cytotoxicity may account for some of the decrease in Tat-mediated expression from the LTR
Preparations of Duck Hepatitis B Virions Contain Multiple DNA Polymerase Activities

AbstractThe hepadnaviral DNA genome is synthesized by a viral-encoded reverse transcriptase, but the nature of this protein(s)in vivoremains obscure. We have previously described studies in which activity gel assays identified multiple DNA polymerase (DNAp) activities associated with highly purified duck hepatitis B virus (DHBV) core particles. We now report that virions isolated from viremic sera are associated with DNA-dependent DNAp activities which are nearly identical to major DNAp activities detected with highly purified DHBV core particles. These results suggest that the virion-associated polymerases are the same as those which are detected with core particles and are likely to represent DHBVpolgene products involved in replication of the genome
Construction of a Chimeric Theiler's Murine Encephalomyelitis Virus Containing the Leader Gene of Foot-and-Mouth Disease Virus

AbstractThe foot-and-mouth disease virus (FMDV) leader coding region (Lb) was cloned into a full-length cDNA of the DA strain of Theiler's murine encephalomyelitis virus (TMEV) replacing the complete L coding region of TMEV. This construct, pDAFSSC1-Lb, was engineered to contain cleavage sites, at the 3′ end of the Lb coding region, for both the FMDV Lb and the TMEV 3C proteases. Transcripts derived from this construct were translated in a cell-free system. Analysis of the translation products showed efficient synthesis and processing of TMEV structural and nonstructural proteins as well as a major band that comigrated with FMDV Lb and was reactive with Lb antiserum. A small plaque virus was recovered from BHK-21 cells transfected with RNA derived from pDAFSSC1-Lb. RT-PCR of RNA isolated from DAFSSC1-Lb virus demonstrated a product corresponding in size and sequence to FMDV Lb. DAFSSC1-Lb virus grew slower than parental virus, DAFSSC1, and to a lower titer. The pattern of viral proteins synthesized in DAFSSC1-Lb virus-infected cells was very similar to the pattern in DAFSSC1 virus-infected cells except that significant amounts of FMDV Lb were produced. In addition, extracts from DAFSSC1-Lb-virus-infected cells cleaved an exogenous source of the translation initiation factor, p220, while DAFSSC1-virus-infected extracts did not. Chimeric viruses that contain coding regions from different picornaviral genera may be valuable tools in investigating the function of particular viral proteins and in studying disease pathogenesis
Phosphorylation of the Herpes Simplex Virus Type 1 Tegument Protein VP22

AbstractThe herpes simplex virus type 1 tegument protein VP22 is known to be highly phosphorylated during infection. Here we show that two electrophoretic forms of VP22 can be identified in infected cell extracts and that this heterogeneity is accounted for by phosphorylation. Furthermore, the nonphosphorylated form of VP22 appears to be specifically incorporated into virions. We also show that the phosphorylated form of VP22 is the only form detected during transient transfection and as such that VP22 can act as a substrate for a cellular kinase. Phospho-amino acid and phospho-peptide analyses ofin vivolabeled VP22 were utilized to demonstrate that the phosphorylation profiles of VP22 synthesized during transfection and infection are the same. In both cases VP22 was modified solely on serine residues located in the N-terminal 120 residues of the protein. Moreover,in vitrophosphorylation was utilized to show that the constitutive cellular kinase, casein kinase II, which has four serine consensus recognition sites at the N-terminus of VP22, phosphorylates VP22 in the same manner as observedin vivo.This kinase also phosphorylates VP22 at the N-terminus in intact capsid–tegument structures. Casein kinase II is therefore likely to be the major kinase of VP22 during infection
RNA Polymerase Activity Catalyzed by a Potyvirus-Encoded RNA-Dependent RNA Polymerase

AbstractWe have expressed the putative RNA-dependent RNA polymerase encoded by the potyvirus tobacco vein mottling virus (TVMV) inEscherichia colias a glutathioneS-transferase fusion protein. As prepared, the fusion protein possessed the poly(U) polymerase activity that is a hallmark of other picornavirus-encoded polymerases. In addition, this protein was able to utilize full-length TVMV RNA as a template for RNA synthesis. A fusion protein containing a mutation in the highly conserved GDD motif of the polymerase (GDD → ADD) possessed 7% of the activity of the wild type. Our results confirm that the presumed polymerase encoded by TVMV is in fact an RNA-dependent RNA polymerase and that the GDD motif so widely seen in viral polymerases has an important function in the TVMV protein
In VivoRepair of 3′-End Deletions in a TCV Satellite RNA May Involve Two Abortive Synthesis and Priming Events

AbstractRNA viruses that do not have the stabilizing features of poly(A) tails or amino acids covalently linked to their 3′ ends must develop other means for protecting or repairing their genomes from damage caused by cellular RNases. We previously found that deletions in the single-stranded tails of a satellite RNA (sat-RNA D) associated with turnip crinkle virus are repairedin vivo(C. D. Carpenter and A.E. Simon, 1996,J. Virol.70, 478–486). We now extend this analysis to show that sat-RNA D transcripts with 3′-end deletions of 5 bases give rise to wild-type sat-RNA, while deletions of 6 to 11 bases result in sat-RNA with additional deletions to the −14 position joined to internal TCV genomic RNA (or other) sequence followed by replacement of the terminal C1−2UGC1−3motif. In addition, we have determined that the selection of internal TCV sequence used in the repair of sat-RNA D 3′ ends is not random and generation of these short TCV segments likely involves primer-mediated synthesis of abortive products facilitated by base-pairing between internal regions of TCV genomic RNA and oligoribonucleotides generated by abortive cycling from the 3′ end of the TCV genome
Structural and Functional Correlates between HIV-1 and SIV Nef Isolates

AbstractThenefgenes of HIV-1 and SIV encode 27–34 kDa myristoylated proteins which have been shown to induce cell surface CD4 downregulation and bind to a cellular protein kinase. To identify regions of Nef important for function, structure–function correlates of HIVSF2nef(Nef) and SIVmm239opennef(SNef) were sought by constructing Nef/SNef hybrids. Metabolic labeling with35[S]methionine/cysteine demonstrated similar amounts of35[S] incorporation into all but one hybrid, SNeftll, in which the C-terminus of SNef was replaced by that of Nef. The weak protein expression of SNeftll was attributable to its short half-life of approximately 45 min. Nef, SNef, and SHSNef, a hybrid containing the internal sequences of Nef and the N- and C-terminal sequences from SNef, downregulated CD4 in human CEM cells. Only Nef and SHSNef downregulated CD4 in mouse AKR1-G1 cells. Nef, SNef, and SHSNef also effectively bound phosphoproteins of MW = 62,000 and 78,000 in CEM cells. Two additional hybrids, in which the Nef sequences of SHSNef were replaced with additional SNef sequences, were essentially ineffective in both assays. Thus, in two different assays of Nef function, swapping the SIV and HIV internalnefsequences were shown to be greatly deleterious to Nef function while SHSNef remained functional