Artigos de revistas: "Virus replication"

1

Lee-Chen, G. J., e M. Woodworth-Gutai. "Evolutionarily selected replication origins: functional aspects and structural organization". Molecular and Cellular Biology 6, n.º 9 (setembro de 1986): 3077–85. http://dx.doi.org/10.1128/mcb.6.9.3077-3085.1986.

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A selective replicative pressure occurs during the evolution of simian virus 40 variants. When the replication origin is duplicated as an inverted repeat, there is a dramatic enhancement of replication. Having regulatory sequences located between the inverted repeat of ori magnifies their enhancing effect on replication. A passage 20 variant and a passage 45 variant containing three pairs of an inverted repeat of ori replicated more efficiently than a passage 13 variant containing nine copies of ori arranged in tandem. A 69-base-pair cellular sequence inserted between inverted repeats of ori of both passage 40 and 45 variants enhanced simian virus 40 DNA replication. Differences in replication efficiencies became greater as the total number of replicating species was increased in the transfection mixture, under conditions where T antigen is limiting. In a competitive environment, sequences flanking the replication origin may be inhibitory to replication.

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2

Lee-Chen, G. J., e M. Woodworth-Gutai. "Evolutionarily selected replication origins: functional aspects and structural organization." Molecular and Cellular Biology 6, n.º 9 (setembro de 1986): 3077–85. http://dx.doi.org/10.1128/mcb.6.9.3077.

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A selective replicative pressure occurs during the evolution of simian virus 40 variants. When the replication origin is duplicated as an inverted repeat, there is a dramatic enhancement of replication. Having regulatory sequences located between the inverted repeat of ori magnifies their enhancing effect on replication. A passage 20 variant and a passage 45 variant containing three pairs of an inverted repeat of ori replicated more efficiently than a passage 13 variant containing nine copies of ori arranged in tandem. A 69-base-pair cellular sequence inserted between inverted repeats of ori of both passage 40 and 45 variants enhanced simian virus 40 DNA replication. Differences in replication efficiencies became greater as the total number of replicating species was increased in the transfection mixture, under conditions where T antigen is limiting. In a competitive environment, sequences flanking the replication origin may be inhibitory to replication.

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3

Avemann, K., R. Knippers, T. Koller e J. M. Sogo. "Camptothecin, a specific inhibitor of type I DNA topoisomerase, induces DNA breakage at replication forks". Molecular and Cellular Biology 8, n.º 8 (agosto de 1988): 3026–34. http://dx.doi.org/10.1128/mcb.8.8.3026-3034.1988.

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The structure of replicating simian virus 40 minichromosomes, extracted from camptothecin-treated infected cells, was investigated by biochemical and electron microscopic methods. We found that camptothecin frequently induced breaks at replication forks close to the replicative growth points. Replication branches were disrupted at about equal frequencies at the leading and the lagging strand sides of the fork. Since camptothecin is known to be a specific inhibitor of type I DNA topoisomerase, we suggest that this enzyme is acting very near the replication forks. This conclusion was supported by experiments with aphidicolin, a drug that blocks replicative fork movement, but did not prevent the camptothecin-induced breakage of replication forks. The drug teniposide, an inhibitor of type II DNA topoisomerase, had only minor effects on the structure of these replicative intermediates.

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4

Avemann, K., R. Knippers, T. Koller e J. M. Sogo. "Camptothecin, a specific inhibitor of type I DNA topoisomerase, induces DNA breakage at replication forks." Molecular and Cellular Biology 8, n.º 8 (agosto de 1988): 3026–34. http://dx.doi.org/10.1128/mcb.8.8.3026.

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The structure of replicating simian virus 40 minichromosomes, extracted from camptothecin-treated infected cells, was investigated by biochemical and electron microscopic methods. We found that camptothecin frequently induced breaks at replication forks close to the replicative growth points. Replication branches were disrupted at about equal frequencies at the leading and the lagging strand sides of the fork. Since camptothecin is known to be a specific inhibitor of type I DNA topoisomerase, we suggest that this enzyme is acting very near the replication forks. This conclusion was supported by experiments with aphidicolin, a drug that blocks replicative fork movement, but did not prevent the camptothecin-induced breakage of replication forks. The drug teniposide, an inhibitor of type II DNA topoisomerase, had only minor effects on the structure of these replicative intermediates.

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5

Targett-Adams, Paul, Steeve Boulant e John McLauchlan. "Visualization of Double-Stranded RNA in Cells Supporting Hepatitis C Virus RNA Replication". Journal of Virology 82, n.º 5 (19 de dezembro de 2007): 2182–95. http://dx.doi.org/10.1128/jvi.01565-07.

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ABSTRACT The mechanisms involved in hepatitis C virus (HCV) RNA replication are unknown, and this aspect of the virus life cycle is not understood. It is thought that virus-encoded nonstructural proteins and RNA genomes interact on rearranged endoplasmic reticulum (ER) membranes to form replication complexes, which are believed to be sites of RNA synthesis. We report that, through the use of an antibody specific for double-stranded RNA (dsRNA), dsRNA is readily detectable in Huh-7 cells that contain replicating HCV JFH-1 genomes but is absent in control cells. Therefore, as that of other RNA virus genomes, the replication of the HCV genome may involve the generation of a dsRNA replicative intermediate. In Huh-7 cells supporting HCV RNA replication, dsRNA was observed as discrete foci, associated with virus-encoded NS5A and core proteins and identical in morphology and distribution to structures containing HCV RNA visualized by fluorescence-based hybridization methods. Three-dimensional reconstruction of deconvolved z-stack images of virus-infected cells provided detailed insight into the relationship among dsRNA foci, NS5A, the ER, and lipid droplets (LDs). This analysis revealed that dsRNA foci were located on the surface of the ER and often surrounded, partially or wholly, by a network of ER-bound NS5A protein. Additionally, virus-induced dsRNA foci were juxtaposed to LDs, attached to the ER. Thus, we report the visualization of HCV-induced dsRNA foci, the likely sites of virus RNA replication, and propose that HCV genome synthesis occurs at LD-associated sites attached to the ER in virus-infected cells.

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6

Blight, Keril J., Jane A. McKeating e Charles M. Rice. "Highly Permissive Cell Lines for Subgenomic and Genomic Hepatitis C Virus RNA Replication". Journal of Virology 76, n.º 24 (15 de dezembro de 2002): 13001–14. http://dx.doi.org/10.1128/jvi.76.24.13001-13014.2002.

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ABSTRACT Hepatitis C virus (HCV) replication appears to be restricted to the human hepatoma cell line Huh-7, indicating that a favorable cellular environment exists within these cells. Although adaptive mutations in the HCV nonstructural proteins typically enhance the replicative capacity of subgenomic replicons in Huh-7 cells, replication can only be detected in a subpopulation of these cells. Here we show that self-replicating subgenomic RNA could be eliminated from Huh-7 clones by prolonged treatment with alpha interferon (IFN-α) and that a higher frequency of cured cells could support both subgenomic and full-length HCV replication. The increased permissiveness of one of the cured cell lines allowed us to readily detect HCV RNA and antigens early after RNA transfection, eliminating the need for selection of replication-positive cells. We also demonstrate that a single amino acid substitution in NS5A is sufficient for establishing HCV replication in a majority of cured cells and that the major phosphate acceptor site of subtype 1b NS5A is not essential for HCV replication.

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7

Peri, Piritta, Veijo Hukkanen, Kristiina Nuutila, Pekka Saukko, Magnus Abrahamson e Tytti Vuorinen. "The cysteine protease inhibitors cystatins inhibit herpes simplex virus type 1-induced apoptosis and virus yield in HEp-2 cells". Journal of General Virology 88, n.º 8 (1 de agosto de 2007): 2101–5. http://dx.doi.org/10.1099/vir.0.82990-0.

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The role of cystatins in herpes simplex virus (HSV)-induced apoptosis and viral replication has been studied. Human epithelial (HEp-2) cells infected with wild-type HSV-1 (F), with a deletion virus lacking the anti-apoptotic gene Us3 (R7041) or with a deletion virus lacking the anti-apoptotic genes Us3 and ICP4 (d120) were treated with cystatin A, C or D. Cells and culture media were studied at different time points for replicating HSV-1 and for apoptosis. Cystatins C and D inhibited the yield of replicative HSV-1 significantly in HEp-2 cells. In addition, cystatin D inhibited R7041 and d120 virus-induced apoptosis. Moreover, cystatin A inhibited R7041-induced apoptosis. These inhibitory effects of cystatins on virus replication and apoptosis are likely to be separate functions. Cystatin D treatment decreased cellular cathepsin B activity in HSV-1 infection, suggesting that cathepsin B is involved in virus-induced apoptosis.

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8

Danovich, R. M., e N. Frenkel. "Herpes simplex virus induces the replication of foreign DNA". Molecular and Cellular Biology 8, n.º 8 (agosto de 1988): 3272–81. http://dx.doi.org/10.1128/mcb.8.8.3272-3281.1988.

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Plasmids containing the simian virus 40 (SV40) DNA replication origin and the large T gene are replicated efficiently in Vero monkey cells but not in rabbit skin cells. Efficient replication of the plasmids was observed in rabbit skin cells infected with herpes simplex virus type 1 (HSV-1) and HSV-2. The HSV-induced replication required the large T antigen and the SV40 replication origin. However, it produced concatemeric molecules resembling replicative intermediates of HSV DNA and was sensitive to phosphonoacetate at concentrations known to inhibit the HSV DNA polymerase. Therefore, it involved the HSV DNA polymerase itself or a viral gene product(s) which was expressed following the replication of HSV DNA. Analyses of test plasmids lacking SV40 or HSV DNA sequences showed that, under some conditions, HSV also induced low-level replication of test plasmids containing no known eucaryotic replication origins. Together, these results show that HSV induces a DNA replicative activity which amplifies foreign DNA. The relevance of these findings to the putative transforming potential of HSV is discussed.

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9

Danovich, R. M., e N. Frenkel. "Herpes simplex virus induces the replication of foreign DNA." Molecular and Cellular Biology 8, n.º 8 (agosto de 1988): 3272–81. http://dx.doi.org/10.1128/mcb.8.8.3272.

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Plasmids containing the simian virus 40 (SV40) DNA replication origin and the large T gene are replicated efficiently in Vero monkey cells but not in rabbit skin cells. Efficient replication of the plasmids was observed in rabbit skin cells infected with herpes simplex virus type 1 (HSV-1) and HSV-2. The HSV-induced replication required the large T antigen and the SV40 replication origin. However, it produced concatemeric molecules resembling replicative intermediates of HSV DNA and was sensitive to phosphonoacetate at concentrations known to inhibit the HSV DNA polymerase. Therefore, it involved the HSV DNA polymerase itself or a viral gene product(s) which was expressed following the replication of HSV DNA. Analyses of test plasmids lacking SV40 or HSV DNA sequences showed that, under some conditions, HSV also induced low-level replication of test plasmids containing no known eucaryotic replication origins. Together, these results show that HSV induces a DNA replicative activity which amplifies foreign DNA. The relevance of these findings to the putative transforming potential of HSV is discussed.

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10

Lu, Hsin-Lin, e Fang Liao. "MDA5 Inhibits the Replication of Hepatitis B Virus (108.13)". Journal of Immunology 188, n.º 1_Supplement (1 de maio de 2012): 108.13. http://dx.doi.org/10.4049/jimmunol.188.supp.108.13.

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Abstract Hepatitis B virus (HBV) infection causes a wide spectrum of liver diseases; however, the innate immunity against HBV infection has been rarely studied and remains elusive. Here, we investigated the involvement of pattern recognition receptors, RIG-I like receptors (RLRs), in HBV replication. We demonstrated that the expression of MDA5, but not RIG-I, was increased in Huh-7 cells transfected with HBV replicative plasmids. Consistent with the in vitro finding, the expression of MDA5, but not RIG-I, was also increased in mice receiving HBV replicative plasmids through hydrodynamic injection. To further determine the effect of RLRs on HBV replication, we cotransfected MDA5 or RIG-I with HBV replicative plasmids into Huh-7 cells and measured HBV replication. The results showed that with similar protein levels of MDA5 and RIG-I, only MDA5, but not RIG-I, significantly inhibited HBV replication. In line with these results, knockdown of MDA5 by siRNA in cells transfected with HBV replicative plasmids increased HBV replication while knockdown of RIG-I did not have any effect on HBV replication. Interestingly, activation of MDA5 by HBV significantly induces IRF3 phosphorylation and NF-κB translocation. This result suggests that HBV-mediated MDA5 activation may be responsible for the IRF3 and NF-κB activation. In summary, our results demonstrate that MDA5, a known cytosolic sensor for RNA virus, contributes to the innate immune response against HBV infection.

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11

Handa, Atsushi, e Kevin E. Brown. "GB virus C/hepatitis G virus replicates in human haematopoietic cells and vascular endothelial cells". Journal of General Virology 81, n.º 10 (1 de outubro de 2000): 2461–69. http://dx.doi.org/10.1099/0022-1317-81-10-2461.

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A novel flavivirus, GB virus C (GBV-C)/hepatitis G virus (HGV), has been detected in chronic liver disease patients. It is known that the viral RNA can be detected in ∼5% of American blood donors. However, the implications for liver disease and the sites of virus replication remain unknown. Possible sites of virus replication were studied by using cell lines and/or primary cells derived from human lymphoid cells, myeloid cells, hepatocytes and endothelial cells. RNA was detected by virus strand-specific RT–PCR and GBV-C/HGV antigen was detected with a rabbit polyclonal anti-E2 (envelope 2) antibody by Western blot analysis. Negative-strand RNA, representative of replicating virus, was detected in lymphoid and megakaryocytoid cell lines and primary vascular endothelial cells. In addition, an increase in virus titre over time was demonstrated and viral antigen was detected, and virus could be passaged to infect fresh cells. However, viral RNA or antigen could not be detected in any of the hepatocyte lines tested. These results indicate that the replication site of GBV-C/HGV is not primarily in hepatocytes and that detection of replicating virus in hepatic tissue may reflect virus replication in haematopoietic cells and/or vascular endothelial cells present in the liver.

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12

Prakash, Om, Bhawana Jain e Amita Jain. "Designing of putative siRNA to inhibit dengue virus replication". International Journal of Research and Development in Pharmacy & Life Sciences 7, n.º 5 (outubro de 2018): 3115–18. http://dx.doi.org/10.21276/ijrdpl.2278-0238.2018.7(5).3115-3118.

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13

Boehmer, Paul, e Amitabh Nimonkar. "Herpes Virus Replication". IUBMB Life (International Union of Biochemistry and Molecular Biology: Life) 55, n.º 1 (1 de janeiro de 2003): 13–22. http://dx.doi.org/10.1080/1521654031000070645.

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14

Kong, Ling, Rebekah Karns, Mohamed Tarek M. Shata, Jennifer L. Brown, Michael S. Lyons, Kenneth E. Sherman e Jason T. Blackard. "The synthetic opioid fentanyl enhances viral replication in vitro". PLOS ONE 16, n.º 4 (14 de abril de 2021): e0249581. http://dx.doi.org/10.1371/journal.pone.0249581.

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The US is in the midst of a major drug epidemic fueled in large part by the widespread recreational use of synthetic opioids such as fentanyl. Persons with opioid use disorder are at significant risk for transmission of injection-associated infections such as hepatitis B virus (HBV) and hepatitis C virus (HCV). Commonly abused substances may antagonize immune responses and promote viral replication. However, the impact of synthetic opioids on virus replication has not been well explored. Thus, we evaluated the impact of fentanyl and carfentanil using in vitro systems that replicate infectious viruses. Fentanyl was used in cell lines replicating HBV or HCV at concentrations of 1 ng, 100 ng, and 10 ug. Viral protein synthesis was quantified by ELISA, while apoptosis and cell death were measured by M30 or MTT assays, respectively. HCV replicative fitness was evaluated in a luciferase-based system. RNAseq was performed to evaluate cellular gene regulation in the presence of fentanyl. Low dose fentanyl had no impact on HCV replication in Huh7.5JFH1 hepatocytes; however, higher doses significantly enhanced HCV replication. Similarly, a dose-dependent increase in HCV replicative fitness was observed in the presence of fentanyl. In the HepG2.2.15 hepatocyte cell line, fentanyl caused a dose-dependent increase in HBV replication, although only a higher doses than for HCV. Addition of fentanyl resulted in significant apoptosis in both hepatocyte cell lines. Cell death was minimal at low drug concentrations. RNAseq identified a number of hepatocyte genes that were differentially regulated by fentanyl, including those related to apoptosis, the antiviral / interferon response, chemokine signaling, and NFκB signaling. Collectively, these data suggest that synthetic opioids promote viral replication but may have distinct effects depending on the drug dose and the viral target. As higher viral loads are associated with pathogenesis and virus transmission, additional research is essential to an enhanced understanding of opioid-virus pathogenesis and for the development of new and optimized treatment strategies.

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15

Snapka, R. M., M. A. Powelson e J. M. Strayer. "Swiveling and decatenation of replicating simian virus 40 genomes in vivo". Molecular and Cellular Biology 8, n.º 2 (fevereiro de 1988): 515–21. http://dx.doi.org/10.1128/mcb.8.2.515-521.1988.

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We have found that type II topoisomerase inhibitors have two effects on replicating simian virus 40 genomes in vivo: production of catenated dimers and slowed replication of the last 5% of the genome. This suggests that type II topoisomerase simultaneously decatenates and facilitates replication fork movement at this stage of DNA replication. On the basis of this observation, a detailed model is proposed for the roles of topoisomerases I and II in simian virus 40 DNA replication.

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16

Snapka, R. M., M. A. Powelson e J. M. Strayer. "Swiveling and decatenation of replicating simian virus 40 genomes in vivo." Molecular and Cellular Biology 8, n.º 2 (fevereiro de 1988): 515–21. http://dx.doi.org/10.1128/mcb.8.2.515.

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We have found that type II topoisomerase inhibitors have two effects on replicating simian virus 40 genomes in vivo: production of catenated dimers and slowed replication of the last 5% of the genome. This suggests that type II topoisomerase simultaneously decatenates and facilitates replication fork movement at this stage of DNA replication. On the basis of this observation, a detailed model is proposed for the roles of topoisomerases I and II in simian virus 40 DNA replication.

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17

Buck, Kenneth W. "Replication of tobacco mosaic virus RNA". Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 354, n.º 1383 (29 de março de 1999): 613–27. http://dx.doi.org/10.1098/rstb.1999.0413.

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The replication of tobacco mosaic virus (TMV) RNA involves synthesis of a negative–strand RNA using the genomic positive–strand RNA as a template, followed by the synthesis of positive–strand RNA on the negative–strand RNA templates. Intermediates of replication isolated from infected cells include completely double–stranded RNA (replicative form) and partly double–stranded and partly single–stranded RNA (replicative intermediate), but it is not known whether these structures are double–stranded or largely single–stranded in vivo . The synthesis of negative strands ceases before that of positive strands, and positive and negative strands may be synthesized by two different polymerases. The genomic–length negative strand also serves as a template for the synthesis of subgenomic mRNAs for the virus movement and coat proteins. Both the virus–encoded 126–kDa protein, which has amino–acid sequence motifs typical of methyltransferases and helicases, and the 183–kDa protein, which has additional motifs characteristic of RNA–dependent RNA polymerases, are required for efficient TMV RNA replication. Purified TMV RNA polymerase also contains a host protein serologically related to the RNA–binding subunit of the yeast translational initiation factor, eIF3. Study of Arabidopsis mutants defective in RNA replication indicates that at least two host proteins are needed for TMV RNA replication. The tomato resistance gene Tm–1 may also encode a mutant form of a host protein component of the TMV replicase. TMV replicase complexes are located on the endoplasmic reticulum in close association with the cytoskeleton in cytoplasmic bodies called viroplasms, which mature to produce ‘X bodies’. Viroplasms are sites of both RNA replication and protein synthesis, and may provide compartments in which the various stages of the virus mutiplication cycle (protein synthesis, RNA replication, virus movement, encapsidation) are localized and coordinated. Membranes may also be important for the configuration of the replicase with respect to initiation of RNA synthesis, and synthesis and release of progeny single–stranded RNA.

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18

Marriott, Anthony C., Joanne M. Smith e Andrew J. Easton. "Fidelity of Leader and Trailer Sequence Usage by the Respiratory Syncytial Virus and Avian Pneumovirus Replication Complexes". Journal of Virology 75, n.º 14 (15 de julho de 2001): 6265–72. http://dx.doi.org/10.1128/jvi.75.14.6265-6272.2001.

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ABSTRACT The specificity of usage of promoters for replication and transcription by the pneumoviruses human respiratory syncytial virus (HRSV) and avian pneumovirus (APV) was studied using minigenomes containing a reporter gene. When infectious HRSV or APV was used as helper virus, replication could occur only if both the leader and trailer regions (containing the replicative and transcriptional promoters) were derived from the helper virus. In contrast, when the HRSV replication complex was supplied from cDNA plasmids, a minigenome containing either the APV leader or trailer was recognized and substantial levels of replication and transcription occurred. These data suggest that in pneumovirus-infected cells, helper virus functions can discriminate between genomes on the basis of the terminal sequences and that there is an association between the leader and trailer required for productive replication. This association is required only in virus-infected cells, not when replication and transcription are mediated by plasmid-directed expression of the component proteins required for replication and transcription. The possible implications of this are discussed.

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19

Reifenberg, Kurt, Petra Nusser, Jürgen Löhler, Gabriele Spindler, Christa Kuhn, Fritz von Weizsäcker e Josef Köck. "Virus replication and virion export in X-deficient hepatitis B virus transgenic mice". Journal of General Virology 83, n.º 5 (1 de maio de 2002): 991–96. http://dx.doi.org/10.1099/0022-1317-83-5-991.

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The function of the X protein (pX) in the replication cycle of mammalian hepadnaviruses is enigmatic. Using tissue culture experiments it has been shown that the X gene product is not central to hepatitis B virus (HBV) replication and virion export. However, at present it is still unclear whether this also applies to the in vivo situation. Using a terminally redundant X-deficient HBV DNA construct, transgenic mice were established that exhibited high-level expression of the viral core protein in liver and kidneys. Importantly, replicative DNA intermediates and mature viral genomes could be detected in the liver and serum of these mice, respectively. These findings indicate that, in the in vivo model of transgenic mice, the HBV X (HBx) gene product is not required for HBV replication and virion secretion.

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Schultz, Kimberly L. W., e Paul D. Friesen. "Baculovirus DNA Replication-Specific Expression Factors Trigger Apoptosis and Shutoff of Host Protein Synthesis during Infection". Journal of Virology 83, n.º 21 (12 de agosto de 2009): 11123–32. http://dx.doi.org/10.1128/jvi.01199-09.

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ABSTRACT Apoptosis is an important antivirus defense. To define the poorly understood pathways by which invertebrates respond to viruses by inducing apoptosis, we have identified replication events that trigger apoptosis in baculovirus-infected cells. We used RNA silencing to ablate factors required for multiplication of Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV). Transfection with double-stranded RNA (dsRNA) complementary to the AcMNPV late expression factors (lefs) that are designated as replicative lefs (lef-1, lef-2, lef-3, lef-11, p143, dnapol, and ie-1/ie-0) blocked virus DNA synthesis and late gene expression in permissive Spodoptera frugiperda cells. dsRNAs specific to designated nonreplicative lefs (lef-8, lef-9, p47, and pp31) blocked late gene expression without affecting virus DNA replication. Thus, both classes of lefs functioned during infection as defined. Silencing the replicative lefs prevented AcMNPV-induced apoptosis of Spodoptera cells, whereas silencing the nonreplicative lefs did not. Thus, the activity of replicative lefs or virus DNA replication is sufficient to trigger apoptosis. Confirming this conclusion, AcMNPV-induced apoptosis was suppressed by silencing the replicative lefs in cells from a divergent species, Drosophila melanogaster. Silencing replicative but not nonreplicative lefs also abrogated AcMNPV-induced shutdown of host protein synthesis, suggesting that virus DNA replication triggers inhibition of host biosynthetic processes and that apoptosis and translational arrest are linked. Our findings suggest that baculovirus DNA replication triggers a host cell response similar to the DNA damage response in vertebrates, which causes translational arrest and apoptosis. Pathways for detecting virus invasion and triggering apoptosis may therefore be conserved between insects and mammals.

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Qiao, Zimu, Jin Wang, Kaiyun Huang, Honghao Hu, Zhouhang Gu, Qiansheng Liao e Zhiyou Du. "The non-template functions of helper virus RNAs create optimal replication conditions to enhance the proliferation of satellite RNAs". PLOS Pathogens 20, n.º 4 (17 de abril de 2024): e1012174. http://dx.doi.org/10.1371/journal.ppat.1012174.

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As a type of parasitic agent, satellite RNAs (satRNAs) rely on cognate helper viruses to achieve their replication and transmission. During the infection of satRNAs, helper virus RNAs serve as templates for synthesizing viral proteins, including the replication proteins essential for satRNA replication. However, the role of non-template functions of helper virus RNAs in satRNA replication remains unexploited. Here we employed the well-studied model that is composed of cucumber mosaic virus (CMV) and its associated satRNA. In the experiments employing the CMV trans-replication system, we observed an unexpected phenomenon the replication proteins of the mild strain LS-CMV exhibited defective in supporting satRNA replication, unlike those of the severe strain Fny-CMV. Independent of translation products, all CMV genomic RNAs could enhance satRNA replication, when combined with the replication proteins of CMV. This enhancement is contingent upon the recruitment and complete replication of helper virus RNAs. Using the method developed for analyzing the satRNA recruitment, we observed a markedly distinct ability of the replication proteins from both CMV strains to recruit the positive-sense satRNA-harboring RNA3 mutant for replication. This is in agreement with the differential ability of both 1a proteins in binding satRNAs in plants. The discrepancies provide a convincing explanation for the variation of the replication proteins of both CMV strains in replicating satRNAs. Taken together, our work provides compelling evidence that the non-template functions of helper virus RNAs create an optimal replication environment to enhance satRNA proliferation.

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Nagy, Peter D., e Wenwu Lin. "Taking over Cellular Energy-Metabolism for TBSV Replication: The High ATP Requirement of an RNA Virus within the Viral Replication Organelle". Viruses 12, n.º 1 (3 de janeiro de 2020): 56. http://dx.doi.org/10.3390/v12010056.

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Recent discoveries on virus-driven hijacking and compartmentalization of the cellular glycolytic and fermentation pathways to support robust virus replication put the spotlight on the energy requirement of viral processes. The active recruitment of glycolytic enzymes in combination with fermentation enzymes by the viral replication proteins emphasizes the advantages of producing ATP locally within viral replication structures. This leads to a paradigm shift in our understanding of how viruses take over host metabolism to support the virus’s energy needs during the replication process. This review highlights our current understanding of how a small plant virus, Tomato bushy stunt virus, exploits a conserved energy-generating cellular pathway during viral replication. The emerging picture is that viruses not only rewire cellular metabolic pathways to obtain the necessary resources from the infected cells but the fast replicating viruses might have to actively hijack and compartmentalize the energy-producing enzymes to provide a readily available source of ATP for viral replication process.

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Grant, Ashley, Alexey Seregin, Cheng Huang, Olga Kolokoltsova, Allan Brasier, Clarence Peters e Slobodan Paessler. "Junín Virus Pathogenesis and Virus Replication". Viruses 4, n.º 10 (19 de outubro de 2012): 2317–39. http://dx.doi.org/10.3390/v4102317.

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24

DiNapoli, Sarah R., Vanessa M. Hirsch e Jason M. Brenchley. "Macrophages in Progressive Human Immunodeficiency Virus/Simian Immunodeficiency Virus Infections". Journal of Virology 90, n.º 17 (15 de junho de 2016): 7596–606. http://dx.doi.org/10.1128/jvi.00672-16.

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The cells that are targeted by primate lentiviruses (HIV and simian immunodeficiency virus [SIV]) are of intense interest given the renewed effort to identify potential cures for HIV. These viruses have been reported to infect multiple cell lineages of hematopoietic origin, including all phenotypic and functional CD4 T cell subsets. The two most commonly reported cell types that become infectedin vivoare memory CD4 T cells and tissue-resident macrophages. Though viral infection of CD4 T cells is routinely detected in both HIV-infected humans and SIV-infected Asian macaques, significant viral infection of macrophages is only routinely observed in animal models wherein CD4 T cells are almost entirely depleted. Here we review the roles of macrophages in lentiviral disease progression, the evidence that macrophages support viral replicationin vivo, the animal models where macrophage-mediated replication of SIV is thought to occur, how the virus can interact with macrophagesin vivo, pathologies thought to be attributed to viral replication within macrophages, how viral replication in macrophages might contribute to the asymptomatic phase of HIV/SIV infection, and whether macrophages represent a long-lived reservoir for the virus.

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Yao, Feng, Nao Murakami, Oliver Bleiziffer, Pengwei Zhang, Natali V. Akhrameyeva, Ximing Xu e Richard Brans. "Development of a Regulatable Oncolytic Herpes Simplex Virus Type 1 Recombinant Virus for Tumor Therapy". Journal of Virology 84, n.º 16 (2 de junho de 2010): 8163–71. http://dx.doi.org/10.1128/jvi.00059-10.

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ABSTRACT Oncolytic viruses are genetically modified viruses that preferentially replicate in host cancer cells, leading to the production of new viruses and, ultimately, cell death. Currently, no oncolytic viruses that are able to kill only tumor cells while leaving normal cells intact are available. Using T-REx (Invitrogen, Carlsbad, CA) gene switch technology and a self-cleaving ribozyme, we have constructed a novel oncolytic HSV-1 recombinant, KTR27, whose replication can be tightly controlled and regulated by tetracycline in a dose-dependent manner. Infection of normal replicating cells as well as multiple human cancer cell types with KTR27 in the presence of tetracycline led to 1,000- to 250,000-fold-higher progeny virus production than in the absence of tetracycline, while little viral replication and virus-associated cytotoxicity was observed in infected growth-arrested normal human cells. We show that intratumoral inoculation with KTR27 markedly inhibits tumor growth in a xenograft model of human non-small-cell lung cancer in nude mice. It is shown further that replication of KTR27 in the inoculated tumors can be efficiently controlled by local codelivery of tetracycline to the target tumors at the time of KTR27 inoculation. Collectively, KTR27 possesses a unique pharmacological feature that can limit its replication to the targeted tumor microenvironment with localized tetracycline delivery, thus minimizing unwanted viral replication in distant tissues following local virotherapy. This regulatory mechanism would also allow the replication of the virus to be quickly shut down should adverse effects be detected.

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Arthos, James, Andrea Rubbert, Ronald L. Rabin, Claudia Cicala, Elizabeth Machado, Kathryne Wildt, Meredith Hanbach et al. "CCR5 Signal Transduction in Macrophages by Human Immunodeficiency Virus and Simian Immunodeficiency Virus Envelopes". Journal of Virology 74, n.º 14 (15 de julho de 2000): 6418–24. http://dx.doi.org/10.1128/jvi.74.14.6418-6424.2000.

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ABSTRACT The capacity of human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) envelopes to transduce signals through chemokine coreceptors on macrophages was examined by measuring the ability of recombinant envelope proteins to mobilize intracellular calcium stores. Both HIV and SIV envelopes mobilized calcium via interactions with CCR5. The kinetics of these responses were similar to those observed when macrophages were treated with MIP-1β. Distinct differences in the capacity of envelopes to mediate calcium mobilization were observed. Envelopes derived from viruses capable of replicating in macrophages mobilized relatively high levels of calcium, while envelopes derived from viruses incapable of replicating in macrophages mobilized relatively low levels of calcium. The failure to efficiently mobilize calcium was not restricted to envelopes derived from CXCR4-utilizing isolates but also included envelopes derived from CCR5-utilizing isolates that fail to replicate in macrophages. We characterized one CCR5-utilizing isolate, 92MW959, which entered macrophages but failed to replicate. A recombinant envelope derived from this virus mobilized low levels of calcium. When macrophages were inoculated with 92MW959 in the presence of MIP-1α, viral replication was observed, indicating that a CC chemokine-mediated signal provided the necessary stimulus to allow the virus to complete its replication cycle. Although the role that envelope-CCR5 signal transduction plays in viral replication is not yet understood, it has been suggested that envelope-mediated signals facilitate early postfusion events in viral replication. The data presented here are consistent with this hypothesis and suggest that the differential capacity of viral envelopes to signal through CCR5 may influence their ability to replicate in macrophages.

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Ball-Goodrich, Lisa J., Elizabeth Johnson e Robert Jacoby. "Divergent replication kinetics of two phenotypically different parvoviruses of rats". Journal of General Virology 82, n.º 3 (1 de março de 2001): 537–46. http://dx.doi.org/10.1099/0022-1317-82-3-537.

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Rat virus (RV) is an important infectious agent of laboratory rats because of its high prevalence and capacity to disrupt research. Additionally, RV infection serves as a model for characterizing virus–host interactions during acute, persistent and prenatal infection. Our research has examined the pathogenesis of two RV strains, RV-UMass and RV-Y. RV-UMass is more pathogenic, causes a higher level of persistent infection and transmits to the foetus after oronasal inoculation of the pregnant dam. To determine in vitro distinctions between the strains that may account for these differences and to provide a benchmark for characterizing virus replication in vivo, synchronized in vitro replication of both RV strains was defined and compared. The results demonstrated that RV replication has replicative intermediates, virus transcripts and proteins similar to those reported for the prototype parvovirus, minute virus of mice. However, the replicative cycle of RV-UMass was 12 h compared with 24 h for RV-Y, and RV-UMass and RV-Y differed in kinetics of virus DNA replication, transcription and protein accumulation. Additionally, in situ analysis correlated well with kinetics data as determined by Southern and Northern blot analysis. Sequence comparisons between the strains also determined coding differences that may contribute to phenotypic differences.

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Zhang, Zhensheng, Ulrike Protzer, Zongyi Hu, James Jacob e T. Jake Liang. "Inhibition of Cellular Proteasome Activities Enhances Hepadnavirus Replication in an HBX-Dependent Manner". Journal of Virology 78, n.º 9 (1 de maio de 2004): 4566–72. http://dx.doi.org/10.1128/jvi.78.9.4566-4572.2004.

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ABSTRACT The X protein (HBX) of the hepatitis B virus (HBV) is not essential for the HBV life cycle in vitro but is important for productive infection in vivo. Our previous study suggests that interaction of HBX with the proteasome complex may underlie the pleiotropic functions of HBX. With the woodchuck model, we demonstrated that the X-deficient mutants of woodchuck hepatitis virus (WHV) are not completely replication defective, possibly behaving like attenuated viruses. In the present study, we analyzed the effects of the proteasome inhibitors on the replication of wild-type and X-negative HBV and WHV. Recombinant adenoviruses or baculoviruses expressing replicating HBV or WHV genomes have been developed as a robust and convenient system to study viral replication in tissue culture. In cells infected with either the recombinant adenovirus-HBV or baculovirus-WHV, the replication level of the X-negative construct was about 10% of that of the wild-type virus. In the presence of proteasome inhibitors, the replication of the wild-type virus was not affected, while the replication of the X-negative virus of either HBV or WHV was enhanced and restored to the wild-type level. Our data suggest that HBX affects hepadnavirus replication through a proteasome-dependent pathway.

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Matano, Tetsuro, Masahiro Kobayashi, Hiroko Igarashi, Akiko Takeda, Hiromi Nakamura, Munehide Kano, Chie Sugimoto et al. "Cytotoxic T Lymphocyte–based Control of Simian Immunodeficiency Virus Replication in a Preclinical AIDS Vaccine Trial". Journal of Experimental Medicine 199, n.º 12 (21 de junho de 2004): 1709–18. http://dx.doi.org/10.1084/jem.20040432.

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Recently, encouraging AIDS vaccine trials in macaques have implicated cytotoxic T lymphocytes (CTLs) in the control of the simian human immunodeficiency virus SHIV89.6P that induces acute CD4+ T cell depletion. However, none of these vaccine regimens have been successful in the containment of replication of the pathogenic simian immunodeficiency viruses (SIVs) that induce chronic disease progression. Indeed, it has remained unclear if vaccine-induced CTL can control SIV replication. Here, we show evidence suggesting that vaccine-induced CTLs control SIVmac239 replication in rhesus macaques. Eight macaques vaccinated with DNA-prime/Gag-expressing Sendai virus vector boost were challenged intravenously with SIVmac239. Five of the vaccinees controlled viral replication and had undetectable plasma viremia after 5 wk of infection. CTLs from all of these five macaques rapidly selected for escape mutations in Gag, indicating that vaccine-induced CTLs successfully contained replication of the challenge virus. Interestingly, analysis of the escape variant selected in three vaccinees that share a major histocompatibility complex class I haplotype revealed that the escape variant virus was at a replicative disadvantage compared with SIVmac239. These findings suggested that the vaccine-induced CTLs had “crippled” the challenge virus. Our results indicate that vaccine induction of highly effective CTLs can result in the containment of replication of a highly pathogenic immunodeficiency virus.

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Bocharov, Gennady, Burkhard Ludewig, Antonio Bertoletti, Paul Klenerman, Tobias Junt, Philippe Krebs, Tatyana Luzyanina, Cristophe Fraser e Roy M. Anderson. "Underwhelming the Immune Response: Effect of Slow Virus Growth on CD8+-T-Lymphocyte Responses". Journal of Virology 78, n.º 5 (1 de março de 2004): 2247–54. http://dx.doi.org/10.1128/jvi.78.5.2247-2254.2004.

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ABSTRACT The speed of virus replication has typically been seen as an advantage for a virus in overcoming the ability of the immune system to control its population growth. Under some circumstances, the converse may also be true: more slowly replicating viruses may evoke weaker cellular immune responses and therefore enhance their likelihood of persistence. Using the model of lymphocytic choriomeningitis virus (LCMV) infection in mice, we provide evidence that slowly replicating strains induce weaker cytotoxic-T-lymphocyte (CTL) responses than a more rapidly replicating strain. Conceptually, we show a “bell-shaped” relationship between the LCMV growth rate and the peak CTL response. Quantitative analysis of human hepatitis C virus infections suggests that a reduction in virus growth rate between patients during the incubation period is associated with a spectrum of disease outcomes, from fulminant hepatitis at the highest rate of viral replication through acute resolving to chronic persistence at the lowest rate. A mathematical model for virus-CTL population dynamics (analogous to predator [CTL]-prey [virus] interactions) is applied in the clinical data-driven analysis of acute hepatitis B virus infection. The speed of viral replication, through its stimulus of host CTL responses, represents an important factor influencing the pathogenesis and duration of virus persistence within the human host. Viruses with lower growth rates may persist in the host because they “sneak through” immune surveillance.

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Wang, Linya, e Jing-hsiung James Ou. "Hepatitis C virus and autophagy". Biological Chemistry 396, n.º 11 (1 de novembro de 2015): 1215–22. http://dx.doi.org/10.1515/hsz-2015-0172.

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Abstract Autophagy is a catabolic process by which cells remove protein aggregates and damaged organelles for recycling. It can also be used by cells to remove intracellular microbial pathogens, including viruses, in a process known as xenophagy. However, many viruses have developed mechanisms to subvert this intracellular antiviral response and even use this pathway to support their own replications. Hepatitis C virus (HCV) is one such virus and is an important human pathogen that can cause severe liver diseases. Recent studies indicated that HCV could activate the autophagic pathway to support its replication. This review summarizes the current knowledge on the interplay between HCV and autophagy and how this interplay affects HCV replication and host innate immune responses.

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Rubino, Luisa, Vitantonio Pantaleo, Beatriz Navarro e Marcello Russo. "Expression of tombusvirus open reading frames 1 and 2 is sufficient for the replication of defective interfering, but not satellite, RNA". Journal of General Virology 85, n.º 10 (1 de outubro de 2004): 3115–22. http://dx.doi.org/10.1099/vir.0.80296-0.

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Yeast cells co-expressing the replication proteins p36 and p95 of Carnation Italian ringspot virus (CIRV) support the RNA-dependent replication of several defective interfering (DI) RNAs derived from either the genome of CIRV or the related Cymbidium ringspot virus (CymRSV), but not the replication of a satellite RNA (sat RNA) originally associated with CymRSV. DI, but not sat RNA, was replicated in yeast cells co-expressing both DI and sat RNA. Using transgenic Nicotiana benthamiana plants constitutively expressing CymRSV replicase proteins (p33 and p92), or transiently expressing either these proteins or CIRV p36 and p95, it was shown that expression of replicase proteins alone was also not sufficient for the replication of sat RNA in plant cells. However, it was also shown that replicating CIRV genomic RNA deletion mutants encoding only replicase proteins could sustain replication of sat RNA in plant cells. These results suggest that sat RNA has a replication strategy differing from that of genomic and DI RNAs, for it requires the presence of a cis-replicating genome acting as a trans-replication enhancer.

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Ali, Naushad, Keith D. Tardif e Aleem Siddiqui. "Cell-Free Replication of the Hepatitis C Virus Subgenomic Replicon". Journal of Virology 76, n.º 23 (1 de dezembro de 2002): 12001–7. http://dx.doi.org/10.1128/jvi.76.23.12001-12007.2002.

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ABSTRACT The hepatitis C virus (HCV) contains a plus-strand RNA genome. The 5′ noncoding region (NCR) of the viral genome functions as an internal ribosome entry site, and its unique 3′ NCR is required for the assembly of the replication complex during initiation of HCV RNA replication. Lohmann et al. (V. Lohmann, F. Korner, J.-O. Koch, U. Herian, L. Theilman, and R. Batenschlager, Science 285:110-113, 1999) developed a subgenomic HCV replicon system, which represents an important tool in studying HCV replication in cultured cells. In this study, we describe a cell-free replication system that utilizes cytoplasmic lysates prepared from Huh-7 cells harboring the HCV subgenomic replicons. These lysates, which contain ribonucleoprotein complexes associated with cellular membranes, were capable of incorporating [α32P]CTP into newly synthesized RNA from subgenomic replicons in vitro. Replicative forms (RFs) and replicative intermediates (RIs) were synthesized from the endogenous HCV RNA templates. Consistent with previous observations, RFs were found to be resistant to RNase A digestion, whereas RIs were sensitive to RNase treatment. The radiolabeled HCV RF-RI complexes contained both minus and plus strands and were specific to the lysates derived from replicon-expressing cells. The availability of a cell-free replication system offers opportunities to probe the mechanism(s) of HCV replication. It also provides a novel assay for potential therapeutic agents.

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Daikoku, Tohru, Ayumi Kudoh, Masatoshi Fujita, Yutaka Sugaya, Hiroki Isomura, Noriko Shirata e Tatsuya Tsurumi. "Architecture of Replication Compartments Formed during Epstein-Barr Virus Lytic Replication". Journal of Virology 79, n.º 6 (15 de março de 2005): 3409–18. http://dx.doi.org/10.1128/jvi.79.6.3409-3418.2005.

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ABSTRACT Epstein-Barr virus (EBV) productive DNA replication occurs at discrete sites, called replication compartments, in nuclei. In this study we performed comprehensive analyses of the architecture of the replication compartments. The BZLF1 oriLyt binding proteins showed a fine, diffuse pattern of distribution throughout the nuclei at immediate-early stages of induction and then became associated with the replicating EBV genome in the replication compartments during lytic infection. The BMRF1 polymerase (Pol) processivity factor showed a homogenous, not dot-like, distribution in the replication compartments, which completely coincided with the newly synthesized viral DNA. Inhibition of viral DNA replication with phosphonoacetic acid, a viral DNA Pol inhibitor, eliminated the DNA-bound form of the BMRF1 protein, although the protein was sufficiently expressed in the cells. These observations together with the findings that almost all abundantly expressed BMRF1 proteins existed in the DNA-bound form suggest that the BMRF1 proteins not only act at viral replication forks as Pol processive factors but also widely distribute on newly replicated EBV genomic DNA. In contrast, the BALF5 Pol catalytic protein, the BALF2 single-stranded-DNA binding protein, and the BBLF2/3 protein, a component of the helicase-primase complex, were colocalized as distinct dots distributed within replication compartments, representing viral replication factories. Whereas cellular replication factories are constructed based on nonchromatin nuclear structures and nuclear matrix, viral replication factories were easily solubilized by DNase I treatment. Thus, compared with cellular DNA replication, EBV lytic DNA replication factories would be simpler so that construction of the replication domain would be more relaxed.

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Weerasooriya, Savithri, Katherine A. DiScipio, Anthar S. Darwish, Ping Bai e Sandra K. Weller. "Herpes simplex virus 1 ICP8 mutant lacking annealing activity is deficient for viral DNA replication". Proceedings of the National Academy of Sciences 116, n.º 3 (31 de dezembro de 2018): 1033–42. http://dx.doi.org/10.1073/pnas.1817642116.

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Most DNA viruses that use recombination-dependent mechanisms to replicate their DNA encode a single-strand annealing protein (SSAP). The herpes simplex virus (HSV) single-strand DNA binding protein (SSB), ICP8, is the central player in all stages of DNA replication. ICP8 is a classical replicative SSB and interacts physically and/or functionally with the other viral replication proteins. Additionally, ICP8 can promote efficient annealing of complementary ssDNA and is thus considered to be a member of the SSAP family. The role of annealing during HSV infection has been difficult to assess in part, because it has not been possible to distinguish between the role of ICP8 as an SSAP from its role as a replicative SSB during viral replication. In this paper, we have characterized an ICP8 mutant, Q706A/F707A (QF), that lacks annealing activity but retains many other functions characteristic of replicative SSBs. Like WT ICP8, the QF mutant protein forms filaments in vitro, binds ssDNA cooperatively, and stimulates the activities of other replication proteins including the viral polymerase, helicase–primase complex, and the origin binding protein. Interestingly, the QF mutant does not complement an ICP8-null virus for viral growth, replication compartment formation, or DNA replication. Thus, we have been able to separate the activities of ICP8 as a replicative SSB from its annealing activity. Taken together, our data indicate that the annealing activity of ICP8 is essential for viral DNA replication in the context of infection and support the notion that HSV-1 uses recombination-dependent mechanisms during DNA replication.

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Beck, Juergen. "Hepatitis B virus replication". World Journal of Gastroenterology 13, n.º 1 (2007): 48. http://dx.doi.org/10.3748/wjg.v13.i1.48.

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LeDesma, Robert, Ila Nimgaonkar e Alexander Ploss. "Hepatitis E Virus Replication". Viruses 11, n.º 8 (6 de agosto de 2019): 719. http://dx.doi.org/10.3390/v11080719.

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Hepatitis E virus (HEV) is a small quasi-enveloped, (+)-sense, single-stranded RNA virus belonging to the Hepeviridae family. There are at least 20 million HEV infections annually and 60,000 HEV-related deaths worldwide. HEV can cause up to 30% mortality in pregnant women and progress to liver cirrhosis in immunocompromised individuals and is, therefore, a greatly underestimated public health concern. Although a prophylactic vaccine for HEV has been developed, it is only licensed in China, and there is currently no effective, non-teratogenic treatment. HEV encodes three open reading frames (ORFs). ORF1 is the largest viral gene product, encoding the replicative machinery of the virus including a methyltransferase, RNA helicase, and an RNA-dependent RNA polymerase. ORF1 additionally contains a number of poorly understood domains including a hypervariable region, a putative protease, and the so-called ‘X’ and ‘Y’ domains. ORF2 is the viral capsid essential for formation of infectious particles and ORF3 is a small protein essential for viral release. In this review, we focus on the domains encoded by ORF1, which collectively mediate the virus’ asymmetric genome replication strategy. We summarize what is known, unknown, and hotly debated regarding the coding and non-coding regions of HEV ORF1, and present a model of how HEV replicates its genome.

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Challberg, M. D., e T. J. Kelly. "Animal Virus DNA Replication". Annual Review of Biochemistry 58, n.º 1 (junho de 1989): 671–713. http://dx.doi.org/10.1146/annurev.bi.58.070189.003323.

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Tao, Yizhi Jane, e Qiaozhen Ye. "RNA Virus Replication Complexes". PLoS Pathogens 6, n.º 7 (22 de julho de 2010): e1000943. http://dx.doi.org/10.1371/journal.ppat.1000943.

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Taylor, John M. "Hepatitis D Virus Replication". Cold Spring Harbor Perspectives in Medicine 5, n.º 11 (novembro de 2015): a021568. http://dx.doi.org/10.1101/cshperspect.a021568.

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Tabata, Keisuke, Christopher J. Neufeldt e Ralf Bartenschlager. "Hepatitis C Virus Replication". Cold Spring Harbor Perspectives in Medicine 10, n.º 3 (30 de setembro de 2019): a037093. http://dx.doi.org/10.1101/cshperspect.a037093.

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Schmid, M., T. Speiseder, T. Dobner e R. A. Gonzalez. "DNA Virus Replication Compartments". Journal of Virology 88, n.º 3 (20 de novembro de 2013): 1404–20. http://dx.doi.org/10.1128/jvi.02046-13.

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McKay, David. "Influenza virus replication blocked". Trends in Biotechnology 19, n.º 5 (maio de 2001): 163. http://dx.doi.org/10.1016/s0167-7799(01)01655-9.

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Nassal, Michael, e Heinz Schaller. "Hepatitis B virus replication". Trends in Microbiology 1, n.º 6 (setembro de 1993): 221–28. http://dx.doi.org/10.1016/0966-842x(93)90136-f.

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Morales, Jose Andre, Peter J. Clarke, Yi Deng e B. M. Golam Kibria. "Characterization of virus replication". Journal in Computer Virology 4, n.º 3 (18 de dezembro de 2007): 221–34. http://dx.doi.org/10.1007/s11416-007-0077-6.

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Bose, Purabi Deka, Bhudev Chandra Das, Rajib Kishore Hazam, Ashok Kumar, Subhash Medhi e Premashis Kar. "Evidence of extrahepatic replication of hepatitis E virus in human placenta". Journal of General Virology 95, n.º 6 (1 de junho de 2014): 1266–71. http://dx.doi.org/10.1099/vir.0.063602-0.

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The incidence and severity of hepatitis E virus (HEV) infection in pregnant women is high in developing countries. Transplacental transmission of HEV in the third trimester of pregnancy has been found to be associated with high fetal mortality. Based on this evidence and in the absence of reports on HEV replication in extrahepatic sites, this study was carried out to investigate if HEV replication occurs in the placenta of infected mothers. The study included 68 acute viral hepatitis (AVH) and 22 acute liver failure (ALF) pregnant patients. Viral RNA was extracted from blood and placenta. HEV replication in placenta was confirmed by a replicative negative-strand-specific reverse transcriptase PCR. Viral load was estimated by real-time PCR. Immunohistochemical studies were also carried out for in situ detection of HEV in placental tissue sections. Replicative HEV RNA was detectable only in the placenta in ALF and AVH cases and not in blood samples. Positive staining of placental tissue sections with HEV antibody against the viral structural protein ORF3 was observed. HEV replication in placenta also correlated with fetal and maternal mortality in ALF patients. It is demonstrated for the first time that HEV replication occurs in human placenta and that placenta may be a site of extrahepatic replication of HEV in humans.

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Zheng, Min, Pui Wang, Wenjun Song, Siu-Ying Lau, Siwen Liu, Xiaofeng Huang, Bobo Wing-Yee Mok et al. "An A14U Substitution in the 3′ Noncoding Region of the M Segment of Viral RNA Supports Replication of Influenza Virus with an NS1 Deletion by Modulating Alternative Splicing of M Segment mRNAs". Journal of Virology 89, n.º 20 (29 de julho de 2015): 10273–85. http://dx.doi.org/10.1128/jvi.00919-15.

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ABSTRACTThe NS1 protein of influenza virus has multiple functions and is a determinant of virulence. Influenza viruses with NS1 deletions (DelNS1 influenza viruses) are a useful tool for studying virus replication and can serve as effective live attenuated vaccines, but deletion of NS1 severely diminishes virus replication, hampering functional studies and vaccine production. We found that WSN-DelNS1 viruses passaged in cells consistently adapted to gain an A14U substitution in the 3′ noncoding region of the M segment of viral RNA (vRNA) which restored replicative ability. DelNS1-M-A14U viruses cannot inhibit interferon expression in virus infected-cells, providing an essential model for studying virus replication in the absence of the NS1 protein. Characterization of DelNS1-M-A14U virus showed that the lack of NS1 has no apparent effect on expression of other viral proteins, with the exception of M mRNAs. Expression of the M transcripts, M1, M2, mRNA3, and mRNA4, is regulated by alternative splicing. The A14U substitution changes the splicing donor site consensus sequence of mRNA3, altering expression of M transcripts, with M2 expression significantly increased and mRNA3 markedly suppressed in DelNS1-M-A14U, but not DelNS1-M-WT, virus-infected cells. Further analysis revealed that the A14U substitution also affects promoter function during replication of the viral genome. The M-A14U mutation increases M vRNA synthesis in DelNS1 virus infection and enhances alternative splicing of M2 mRNA in the absence of other viral proteins. The findings demonstrate that NS1 is directly involved in influenza virus replication through modulation of alternative splicing of M transcripts and provide strategic information important to construction of vaccine strains with NS1 deletions.IMPORTANCENonstructural protein (NS1) of influenza virus has multiple functions. Besides its role in antagonizing host antiviral activity, NS1 is also believed to be involved in regulating virus replication, but mechanistic details are not clear. The NS1 protein is a virulence determinant which inhibits both innate and adaptive immunity and live attenuated viruses with NS1 deletions show promise as effective vaccines. However, deletion of NS1 causes severe attenuation of virus replication during infection, impeding functional studies and vaccine development. We characterized a replication-competent DelNS1 virus which carries an A14U substitution in the 3′ noncoding region of the vRNA M segment. We found that M-A14U mutation supports virus replication through modulation of alternative splicing of mRNAs transcribed from the M segment. Our findings give insight into the role of NS1 in influenza virus replication and provide an approach for constructing replication-competent strains with NS1 deletions for use in functional and vaccine studies.

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Dunn, Ewan F., Rachel Fearns e John H. Connor. "Akt Inhibitor Akt-IV Blocks Virus Replication through an Akt-Independent Mechanism". Journal of Virology 83, n.º 22 (9 de setembro de 2009): 11665–72. http://dx.doi.org/10.1128/jvi.01092-09.

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ABSTRACT Many viruses activate the phosphatidylinositol 3′-kinase (PI3k)/Akt intracellular signaling pathway to promote viral replication. We have analyzed whether a rapidly replicating rhabdovirus, vesicular stomatitis virus (VSV), requires the PI3k/Akt signaling pathway for its replication. Through the use of chemical inhibitors of PI3k and Akt, we show that VSV replication and cytopathic effects do not require activation of these kinases. Inhibitors that block the activating phosphorylations of Akt at threonine 308 (Thr308) and serine 473 (Ser473) did not inhibit VSV protein expression or the induction of the cytopathic effects of VSV. One compound, Akt inhibitor Akt-IV, inhibited the replication of VSV, respiratory syncytial virus, and vaccinia virus but increased the phosphorylation of Akt at positions Thr308 and Ser473 and did not inhibit Akt kinase activity in vitro. Together, our data suggest that the PI3k/Akt pathway is of limited relevance to the replication of VSV but that Akt inhibitor Akt-IV is a novel broad-spectrum antiviral compound with a mechanism differing from that of its previously reported effect on the PI3k/Akt pathway. Identification of other targets for this compound may define a new approach for blocking virus replication.

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Nicolas, Armel, Nathalie Alazard-Dany, Coline Biollay, Loredana Arata, Nelly Jolinon, Lauriane Kuhn, Myriam Ferro et al. "Identification of Rep-Associated Factors in Herpes Simplex Virus Type 1-Induced Adeno-Associated Virus Type 2 Replication Compartments". Journal of Virology 84, n.º 17 (23 de junho de 2010): 8871–87. http://dx.doi.org/10.1128/jvi.00725-10.

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ABSTRACT Adeno-associated virus (AAV) is a human parvovirus that replicates only in cells coinfected with a helper virus, such as adenovirus or herpes simplex virus type 1 (HSV-1). We previously showed that nine HSV-1 factors are able to support AAV rep gene expression and genome replication. To elucidate the strategy of AAV replication in the presence of HSV-1, we undertook a proteomic analysis of cellular and HSV-1 factors associated with Rep proteins and thus potentially recruited within AAV replication compartments (AAV RCs). This study resulted in the identification of approximately 60 cellular proteins, among which factors involved in DNA and RNA metabolism represented the largest functional categories. Validation analyses indicated that the cellular DNA replication enzymes RPA, RFC, and PCNA were recruited within HSV-1-induced AAV RCs. Polymerase δ was not identified but subsequently was shown to colocalize with Rep within AAV RCs even in the presence of the HSV-1 polymerase complex. In addition, we found that AAV replication is associated with the recruitment of components of the Mre11/Rad50/Nbs1 complex, Ku70 and -86, and the mismatch repair proteins MSH2, -3, and -6. Finally, several HSV-1 factors were also found to be associated with Rep, including UL12. We demonstrated for the first time that this protein plays a role during AAV replication by enhancing the resolution of AAV replicative forms and AAV particle production. Altogether, these analyses provide the basis to understand how AAV adapts its replication strategy to the nuclear environment induced by the helper virus.

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Ali, Md Emran, e Sumyya Waliullah. "A Core35S Promoter of Cauliflower Mosaic Virus Drives More Efficient Replication of Turnip Crinkle Virus". Plants 10, n.º 8 (18 de agosto de 2021): 1700. http://dx.doi.org/10.3390/plants10081700.

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The 35S promoter with a duplicated enhancer (frequently referred to as 2X35S) is a strong dicotyledonous plant-specific promoter commonly used in generating transgenic plants to enable high-level expression of genes of interest. It is also used to drive the initiation of RNA virus replication from viral cDNA, with the consensus understanding that high levels of viral RNA production powered by 2X35S permit a more efficient initiation of virus replication. Here, we showed that the exact opposite is true. We found that, compared to the Core35S promoter, the 2X35S promoter-driven initiation of turnip crinkle virus (TCV) infection was delayed by at least 24 h. We first compared three versions of 35S promoter, namely 2X35S, 1X35S, and Core35S, for their ability to power the expression of a non-replicating green fluorescent protein (GFP) gene, and confirmed that 2X35S and Core35S correlated with the highest and lowest GFP expression, respectively. However, when inserted upstream of TCV cDNA, 2X35S-driven replication was not detected until 72 h post-inoculation (72 hpi) in inoculated leaves. By contrast, Core35S-driven replication was detected earlier at 48 hpi. A similar delay was also observed in systemically infected leaves (six versus four days post-inoculation). Combining our results, we hypothesized that the stronger 2X35S promoter might enable a higher accumulation of a TCV protein that became a repressor of TCV replication at higher cellular concentration. Extending from these results, we propose that the Core35S (or mini35S) promoter is likely a better choice for generating infectious cDNA clones of TCV.

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