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  1. Article ; Online: Distinctive features of the respiratory syncytial virus priming loop compared to other non-segmented negative strand RNA viruses.

    Cressey, Tessa N / Shareef, Afzaal M / Kleiner, Victoria A / Noton, Sarah L / Byrne, Patrick O / McLellan, Jason S / Mühlberger, Elke / Fearns, Rachel

    PLoS pathogens

    2022  Volume 18, Issue 6, Page(s) e1010451

    Abstract: De novo initiation by viral RNA-dependent RNA polymerases often requires a polymerase priming residue, located within a priming loop, to stabilize the initiating NTPs. Polymerase structures from three different non-segmented negative strand RNA virus ( ... ...

    Abstract De novo initiation by viral RNA-dependent RNA polymerases often requires a polymerase priming residue, located within a priming loop, to stabilize the initiating NTPs. Polymerase structures from three different non-segmented negative strand RNA virus (nsNSV) families revealed putative priming loops in different conformations, and an aromatic priming residue has been identified in the rhabdovirus polymerase. In a previous study of the respiratory syncytial virus (RSV) polymerase, we found that Tyr1276, the L protein aromatic amino acid residue that most closely aligns with the rhabdovirus priming residue, is not required for RNA synthesis but two nearby residues, Pro1261 and Trp1262, were required. In this study, we examined the roles of Pro1261 and Trp1262 in RNA synthesis initiation. Biochemical studies showed that substitution of Pro1261 inhibited RNA synthesis initiation without inhibiting back-priming, indicating a defect in initiation. Biochemical and minigenome experiments showed that the initiation defect incurred by a P1261A substitution could be rescued by factors that would be expected to increase the stability of the initiation complex, specifically increased NTP concentration, manganese, and a more efficient promoter sequence. These findings indicate that Pro1261 of the RSV L protein plays a role in initiation, most likely in stabilizing the initiation complex. However, we found that substitution of the corresponding proline residue in a filovirus polymerase had no effect on RNA synthesis initiation or elongation. These results indicate that despite similarities between the nsNSV polymerases, there are differences in the features required for RNA synthesis initiation.
    MeSH term(s) Humans ; Promoter Regions, Genetic ; RNA, Viral/genetics ; RNA, Viral/metabolism ; RNA-Dependent RNA Polymerase/genetics ; Respiratory Syncytial Virus, Human/genetics ; Respiratory Syncytial Virus, Human/metabolism ; Rhabdoviridae/genetics
    Chemical Substances RNA, Viral ; RNA-Dependent RNA Polymerase (EC 2.7.7.48)
    Language English
    Publishing date 2022-06-22
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 2205412-1
    ISSN 1553-7374 ; 1553-7374
    ISSN (online) 1553-7374
    ISSN 1553-7374
    DOI 10.1371/journal.ppat.1010451
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Differential Mechanisms for the Involvement of Polyamines and Hypusinated eIF5A in Ebola Virus Gene Expression.

    Olsen, Michelle E / Cressey, Tessa N / Mühlberger, Elke / Connor, John H

    Journal of virology

    2018  Volume 92, Issue 20

    Abstract: Polyamines and hypusinated eIF5A have been implicated in the replication of diverse viruses; however, defining their roles in supporting virus replication is still under investigation. We have previously reported that Ebola virus (EBOV) requires ... ...

    Abstract Polyamines and hypusinated eIF5A have been implicated in the replication of diverse viruses; however, defining their roles in supporting virus replication is still under investigation. We have previously reported that Ebola virus (EBOV) requires polyamines and hypusinated eIF5A for replication. Using a replication-deficient minigenome construct, we show that gene expression, in the absence of genome replication, requires hypusinated eIF5A. Additional experiments demonstrated that the block in gene expression upon hypusine depletion was posttranscriptional, as minigenome reporter mRNA transcribed by the EBOV polymerase accumulated normally in the presence of drug treatment where protein did not. When this mRNA was isolated from cells with low levels of hypusinated eIF5A and transfected into cells with normal eIF5A function, minigenome reporter protein accumulation was normal, demonstrating that the mRNA produced was functional but required hypusinated eIF5A function for translation. Our results support a mechanism in which hypusinated eIF5A is required for the translation, but not synthesis, of EBOV transcripts. In contrast, depletion of polyamines with difluoromethylornithine (DFMO) resulted in a strong block in the accumulation of EBOV polymerase-produced mRNA, indicating a different mechanism of polyamine suppression of EBOV gene expression. Supplementing with exogenous polyamines after DFMO treatment restored mRNA accumulation and luciferase activity. These data indicate that cellular polyamines are required for two distinct aspects of the EBOV life cycle. The bifunctional requirement for polyamines underscores the importance of these cellular metabolites in EBOV replication and suggests that repurposing existing inhibitors of this pathway could be an effective approach for EBOV therapeutics.
    MeSH term(s) Animals ; Cell Line ; Ebolavirus/physiology ; Gene Expression ; Host-Pathogen Interactions ; Mesocricetus ; Peptide Initiation Factors/metabolism ; Polyamines/metabolism ; Protein Biosynthesis ; Protein Processing, Post-Translational ; RNA-Binding Proteins/metabolism ; Viral Proteins/biosynthesis ; Eukaryotic Translation Initiation Factor 5A
    Chemical Substances Peptide Initiation Factors ; Polyamines ; RNA-Binding Proteins ; Viral Proteins
    Language English
    Publishing date 2018-09-26
    Publishing country United States
    Document type Journal Article
    ZDB-ID 80174-4
    ISSN 1098-5514 ; 0022-538X
    ISSN (online) 1098-5514
    ISSN 0022-538X
    DOI 10.1128/JVI.01260-18
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Mechanism for de novo initiation at two sites in the respiratory syncytial virus promoter.

    Cressey, Tessa N / Noton, Sarah L / Nagendra, Kartikeya / Braun, Molly R / Fearns, Rachel

    Nucleic acids research

    2018  Volume 46, Issue 13, Page(s) 6785–6796

    Abstract: The respiratory syncytial virus (RSV) RNA dependent RNA polymerase (RdRp) initiates two RNA synthesis processes from the viral promoter: genome replication from position 1U and mRNA transcription from position 3C. Here, we examined the mechanism by which ...

    Abstract The respiratory syncytial virus (RSV) RNA dependent RNA polymerase (RdRp) initiates two RNA synthesis processes from the viral promoter: genome replication from position 1U and mRNA transcription from position 3C. Here, we examined the mechanism by which a single promoter can direct initiation from two sites. We show that initiation at 1U and 3C occurred independently of each other, and that the same RdRp was capable of precisely selecting the two sites. The RdRp preferred to initiate at 3C, but initiation site selection could be modulated by the relative concentrations of ATP versus GTP. Analysis of template mutations indicated that the RdRp could bind ATP and CTP, or GTP, independently of template nucleotides. The data suggest a model in which innate affinity of the RdRp for particular NTPs, coupled with a repeating element within the promoter, allows precise initiation of replication at 1U or transcription at 3C.
    MeSH term(s) Adenosine Triphosphate/metabolism ; Cell Line ; Guanosine Triphosphate/metabolism ; Promoter Regions, Genetic ; RNA Replicase/metabolism ; Respiratory Syncytial Viruses/enzymology ; Respiratory Syncytial Viruses/genetics ; Respiratory Syncytial Viruses/physiology ; Templates, Genetic ; Transcription Initiation Site ; Transcription Initiation, Genetic ; Virus Replication
    Chemical Substances Guanosine Triphosphate (86-01-1) ; Adenosine Triphosphate (8L70Q75FXE) ; RNA Replicase (EC 2.7.7.48)
    Language English
    Publishing date 2018-06-01
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 186809-3
    ISSN 1362-4962 ; 1362-4954 ; 0301-5610 ; 0305-1048
    ISSN (online) 1362-4962 ; 1362-4954
    ISSN 0301-5610 ; 0305-1048
    DOI 10.1093/nar/gky480
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Ebolavirus polymerase uses an unconventional genome replication mechanism.

    Deflubé, Laure R / Cressey, Tessa N / Hume, Adam J / Olejnik, Judith / Haddock, Elaine / Feldmann, Friederike / Ebihara, Hideki / Fearns, Rachel / Mühlberger, Elke

    Proceedings of the National Academy of Sciences of the United States of America

    2019  Volume 116, Issue 17, Page(s) 8535–8543

    Abstract: Most nonsegmented negative strand (NNS) RNA virus genomes have complementary 3' and 5' terminal nucleotides because the promoters at the 3' ends of the genomes and antigenomes are almost identical to each other. However, according to published sequences, ...

    Abstract Most nonsegmented negative strand (NNS) RNA virus genomes have complementary 3' and 5' terminal nucleotides because the promoters at the 3' ends of the genomes and antigenomes are almost identical to each other. However, according to published sequences, both ends of ebolavirus genomes show a high degree of variability, and the 3' and 5' terminal nucleotides are not complementary. If correct, this would distinguish the ebolaviruses from other NNS RNA viruses. Therefore, we investigated the terminal genomic and antigenomic nucleotides of three different ebolavirus species, Ebola (EBOV), Sudan, and Reston viruses. Whereas the 5' ends of ebolavirus RNAs are highly conserved with the sequence ACAGG-5', the 3' termini are variable and are typically 3'-GCCUGU, ACCUGU, or CCUGU. A small fraction of analyzed RNAs had extended 3' ends. The majority of 3' terminal sequences are consistent with a mechanism of nucleotide addition by hairpin formation and back-priming. Using single-round replicating EBOV minigenomes, we investigated the effect of the 3' terminal nucleotide on viral replication and found that the EBOV polymerase initiates replication opposite the 3'-CCUGU motif regardless of the identity of the 3' terminal nucleotide(s) and of the position of this motif relative to the 3' end. Deletion or mutation of the first residue of the 3'-CCUGU motif completely abolished replication initiation, suggesting a crucial role of this nucleotide in directing initiation. Together, our data show that ebolaviruses have evolved a unique replication strategy among NNS RNA viruses resulting in 3' overhangs. This could be a mechanism to avoid antiviral recognition.
    MeSH term(s) Base Sequence/genetics ; Ebolavirus/genetics ; Ebolavirus/metabolism ; Ebolavirus/physiology ; Genome, Viral/genetics ; Nucleotides/genetics ; RNA, Viral/biosynthesis ; RNA, Viral/genetics ; Virus Replication/genetics
    Chemical Substances Nucleotides ; RNA, Viral
    Language English
    Publishing date 2019-04-08
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 209104-5
    ISSN 1091-6490 ; 0027-8424
    ISSN (online) 1091-6490
    ISSN 0027-8424
    DOI 10.1073/pnas.1815745116
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: A Chimeric Lloviu Virus Minigenome System Reveals that the Bat-Derived Filovirus Replicates More Similarly to Ebolaviruses than Marburgviruses.

    Manhart, Whitney A / Pacheco, Jennifer R / Hume, Adam J / Cressey, Tessa N / Deflubé, Laure R / Mühlberger, Elke

    Cell reports

    2018  Volume 24, Issue 10, Page(s) 2573–2580.e4

    Abstract: Recently, traces of zoonotic viruses have been discovered in bats and other species around the world, but despite repeated attempts, full viral genomes have not been rescued. The absence of critical genetic sequences from these viruses and the ... ...

    Abstract Recently, traces of zoonotic viruses have been discovered in bats and other species around the world, but despite repeated attempts, full viral genomes have not been rescued. The absence of critical genetic sequences from these viruses and the difficulties to isolate infectious virus from specimens prevent research on their pathogenic potential for humans. One example of these zoonotic pathogens is Lloviu virus (LLOV), a filovirus that is closely related to Ebola virus. Here, we established LLOV minigenome systems based on sequence complementation from other filoviruses. Our results show that the LLOV replication and transcription mechanisms are, in general, more similar to ebolaviruses than to marburgviruses. We also show that a single nucleotide at the 3' genome end determines species specificity of the LLOV polymerase. The data obtained here will be instrumental for the rescue of infectious LLOV clones for pathogenesis studies.
    MeSH term(s) Animals ; Cell Line, Tumor ; Chiroptera/virology ; Ebolavirus/genetics ; Ebolavirus/pathogenicity ; Filoviridae/genetics ; Filoviridae/pathogenicity ; Genome, Viral/genetics ; HEK293 Cells ; Humans ; Marburgvirus/genetics ; Marburgvirus/pathogenicity ; RNA Replicase/genetics ; RNA Replicase/metabolism ; Virus Replication/genetics ; Virus Replication/physiology
    Chemical Substances RNA Replicase (EC 2.7.7.48)
    Language English
    Publishing date 2018-09-26
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 2649101-1
    ISSN 2211-1247 ; 2211-1247
    ISSN (online) 2211-1247
    ISSN 2211-1247
    DOI 10.1016/j.celrep.2018.08.008
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: An RNA polymerase II-driven Ebola virus minigenome system as an advanced tool for antiviral drug screening.

    Nelson, Emily V / Pacheco, Jennifer R / Hume, Adam J / Cressey, Tessa N / Deflubé, Laure R / Ruedas, John B / Connor, John H / Ebihara, Hideki / Mühlberger, Elke

    Antiviral research

    2017  Volume 146, Page(s) 21–27

    Abstract: Ebola virus (EBOV) causes a severe disease in humans with the potential for significant international public health consequences. Currently, treatments are limited to experimental vaccines and therapeutics. Therefore, research into prophylaxis and ... ...

    Abstract Ebola virus (EBOV) causes a severe disease in humans with the potential for significant international public health consequences. Currently, treatments are limited to experimental vaccines and therapeutics. Therefore, research into prophylaxis and antiviral strategies to combat EBOV infections is of utmost importance. The requirement for high containment laboratories to study EBOV infection is a limiting factor for conducting EBOV research. To overcome this issue, minigenome systems have been used as valuable tools to study EBOV replication and transcription mechanisms and to screen for antiviral compounds at biosafety level 2. The most commonly used EBOV minigenome system relies on the ectopic expression of the T7 RNA polymerase (T7), which can be limiting for certain cell types. We have established an improved EBOV minigenome system that utilizes endogenous RNA polymerase II (pol II) as a driver for the synthesis of minigenome RNA. We show here that this system is as efficient as the T7-based minigenome system, but works in a wider range of cell types, including biologically relevant cell types such as bat cells. Importantly, we were also able to adapt this system to a reliable and cost-effective 96-well format antiviral screening assay with a Z-factor of 0.74, indicative of a robust assay. Using this format, we identified JG40, an inhibitor of Hsp70, as an inhibitor of EBOV replication, highlighting the potential for this system as a tool for antiviral drug screening. In summary, this updated EBOV minigenome system provides a convenient and effective means of advancing the field of EBOV research.
    MeSH term(s) Animals ; Antiviral Agents/isolation & purification ; Antiviral Agents/pharmacology ; DNA-Directed RNA Polymerases/genetics ; DNA-Directed RNA Polymerases/metabolism ; Ebolavirus/drug effects ; Ebolavirus/enzymology ; Ebolavirus/genetics ; Genome, Viral ; HSP72 Heat-Shock Proteins/antagonists & inhibitors ; Hemorrhagic Fever, Ebola/virology ; High-Throughput Screening Assays/economics ; High-Throughput Screening Assays/instrumentation ; High-Throughput Screening Assays/methods ; Humans ; Microbial Sensitivity Tests/economics ; Microbial Sensitivity Tests/instrumentation ; Microbial Sensitivity Tests/methods ; RNA Polymerase II/genetics ; RNA Polymerase II/metabolism ; RNA, Viral/genetics ; Transcription, Genetic/drug effects ; Viral Proteins/genetics ; Viral Proteins/metabolism ; Virus Replication/drug effects
    Chemical Substances Antiviral Agents ; HSP72 Heat-Shock Proteins ; RNA, Viral ; Viral Proteins ; RNA Polymerase II (EC 2.7.7.-) ; bacteriophage T7 RNA polymerase (EC 2.7.7.-) ; DNA-Directed RNA Polymerases (EC 2.7.7.6)
    Language English
    Publishing date 2017-08-12
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 306628-9
    ISSN 1872-9096 ; 0166-3542
    ISSN (online) 1872-9096
    ISSN 0166-3542
    DOI 10.1016/j.antiviral.2017.08.005
    Database MEDical Literature Analysis and Retrieval System OnLINE

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