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MicroRNAs derived from the insect virus HzNV-1 promote lytic infection by suppressing histone methylation. Sci Rep 2018; 8:17817. [PMID: 30546025 PMCID: PMC6292938 DOI: 10.1038/s41598-018-35782-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 11/06/2018] [Indexed: 12/19/2022] Open
Abstract
Heliothis zea nudivirus-1 (HzNV-1) is an insect virus that can induce both lytic and latent infections in various insect cell lines. During latent infection, several microRNAs (miRNAs) are produced from persistency-associated gene 1 (pag1) as the only detectable HzNV-1 transcript. Previous studies have shown that the pag1 gene suppresses the immediate-early gene hhi1 and promotes host switching into a latent infection via miRNAs derived from pag1. Although other functions of the miRNAs derived from pag1 have not yet been elucidated, several studies have suggested that miRNAs encoded from latency-associated genes can regulate histone-associated enzymes. Because pag1 is a noncoding transcript, it potentially regulates host chromatin structure through miRNAs upon infection. Nevertheless, the exact mechanism by which pag1 alters viral infections remains unknown. In this study, we found that the pag1-encoded miRNA miR-420 suppresses expression of the histone modification-associated enzyme su(var)3-9. Therefore, this miRNA causes histone modification to promote HzNV-1 infection. These results suggest that HzNV-1 may directly influence epigenetic regulation in host cells through interactions with pag1 miRNAs to promote lytic infection. This study provides us with a better understanding of both the HzNV-1 infection pathway and the relationship between viral miRNAs and epigenetic regulation.
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2
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Volkman LE. Baculoviruses and nucleosome management. Virology 2015; 476:257-263. [PMID: 25569454 DOI: 10.1016/j.virol.2014.12.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 12/09/2014] [Accepted: 12/10/2014] [Indexed: 11/30/2022]
Abstract
Negatively-supercoiled-ds DNA molecules, including the genomes of baculoviruses, spontaneously wrap around cores of histones to form nucleosomes when present within eukaryotic nuclei. Hence, nucleosome management should be essential for baculovirus genome replication and temporal regulation of transcription, but this has not been documented. Nucleosome mobilization is the dominion of ATP-dependent chromatin-remodeling complexes. SWI/SNF and INO80, two of the best-studied complexes, as well as chromatin modifier TIP60, all contain actin as a subunit. Retrospective analysis of results of AcMNPV time course experiments wherein actin polymerization was blocked by cytochalasin D drug treatment implicate actin-containing chromatin modifying complexes in decatenating baculovirus genomes, shutting down host transcription, and regulating late and very late phases of viral transcription. Moreover, virus-mediated nuclear localization of actin early during infection may contribute to nucleosome management.
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Affiliation(s)
- Loy E Volkman
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
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3
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Wu YL, Wu CP, Liu CYY, Hsu PWC, Wu EC, Chao YC. A non-coding RNA of insect HzNV-1 virus establishes latent viral infection through microRNA. Sci Rep 2011; 1:60. [PMID: 22355579 PMCID: PMC3216547 DOI: 10.1038/srep00060] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Accepted: 07/22/2011] [Indexed: 11/17/2022] Open
Abstract
Heliothis zea nudivirus-1 (HzNV-1) is an insect virus previously known as Hz-1 baculovirus. One of its major early genes, hhi1, is responsible for the establishment of productive viral infection; another gene, pag1, which expresses a non-coding RNA, is the only viral transcript detectable during viral latency. Here we showed that this non-coding RNA was further processed into at least two distinct miRNAs, which targeted and degraded hhi1 transcript. This is a result strikingly similar to a recent report that herpes simplex virus produces tightly-regulated latent specific miRNAs to silence its own key early transcripts. Nevertheless, proof for the establishment of viral latency by miRNA is still lacking. We further showed that HzNV-1 latency could be directly induced by pag1-derived miRNAs in cells infected with a pag1-deleted, latency-deficient virus. This result suggests the existence of a novel mechanism, where miRNAs can be functional for the establishment of viral latency.
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Affiliation(s)
- Yueh-Lung Wu
- Institute of Molecular Biology, Academia Sinica, Nankang, Taipei 105; Taiwan
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4
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Heliothis zea nudivirus 1 gene hhi1 induces apoptosis which is blocked by the Hz-iap2 gene and a noncoding gene, pag1. J Virol 2011; 85:6856-66. [PMID: 21543471 DOI: 10.1128/jvi.01843-10] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Heliothis zea nudivirus 1 (HzNV-1 or Hz-1 virus), previously regarded as a nonoccluded baculovirus, recently has been placed in the Nudivirus genus. This virus generates HzNV-1 HindIII-I 1 (hhi1) and many other transcripts during productive viral infection; during latent viral infection, however, persistency-associated gene 1 (pag1) is the only gene expressed. In this report, we used transient expression assays to show that hhi1 can trigger strong apoptosis in transfected cells, which can be blocked, at least partially, by the inhibitor of apoptosis genes Autographa californica iap2 (Ac-iap2) and H. zea iap2 (Hz-iap2). In addition to these two genes, unexpectedly, pag1, which encodes a noncoding RNA with no detectable protein product, was found to efficiently suppress hhi1-induced apoptosis. The assay of pro-Sf-caspase-1 processing by hhi1 transfection did not detect the small P12 subunit at any of the time intervals tested, suggesting that hhi1 of HzNV-1 induces apoptosis through alternative caspase pathways.
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5
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Burand JP, Stiles B, Wood HA. Structural and Intracellular Proteins of the Nonoccluded Baculovirus HZ-1. J Virol 2010; 46:137-42. [PMID: 16789238 PMCID: PMC255101 DOI: 10.1128/jvi.46.1.137-142.1983] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A plaque-purified isolate of the baculovirus HZ-1 was used to examine the kinetics of replication of this persistent, nonoccluded virus in TN-368 cells. Twenty-eight virus structural proteins ranging in molecular weight from 153,000 to 14,000 were identified. Fourteen of these proteins were found to be glycosylated. The sequence of appearance of the 37 virus-induced intracellular polypeptides was determined by pulse-labeling with [(35)S]methionine. N-[(3)H]acetylglucosamine, [(3)H]mannose, and the glycosylation inhibitor tunicamycin were used to detect virus structural glycoproteins. Post-transcriptional modification of two virus-induced proteins was detected.
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Affiliation(s)
- J P Burand
- Boyce Thompson Institute for Plant Research, Ithaca, New York 14853
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6
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The early gene hhi1 reactivates Heliothis zea nudivirus 1 in latently infected cells. J Virol 2009; 84:1057-65. [PMID: 19889784 DOI: 10.1128/jvi.01548-09] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Heliothis zea nudivirus 1 (HzNV-1), previously known as Hz-1 virus, is an insect virus able to establish both productive and latent infections in several lepidopteran insect cells. Here, we have cloned and characterized one of the HzNV-1 early genes, hhi1, which maps to the HindIII-I fragment of the viral genome. During the productive viral infection, a 6.2-kb hhi1 transcript was detectable as early as 0.5 h postinfection (hpi). The level of transcript reached a maximum at 2 hpi and gradually decreased after 4 hpi. The transcript was not detectable during the latent phase of viral infection. Upon cycloheximide treatment, much higher levels of hhi1 transcript were detected throughout the productive viral infection cycle, suggesting that newly synthesized proteins are not needed for the expression of hhi1. Nevertheless, viral coinfection can further stimulate the expression of transfected hhi1 promoter in a plasmid. Transient hhi1 expression in latently infected cells resulted in a significant increase in virus titer and viral DNA propagation, suggesting that hhi1 plays a critical role in viral reactivation. Additional experiments showed that six early genes, which possibly function in transcription or DNA replication, were activated in the latent cells upon hhi1 transfection. Among these six genes, orf90 and orf121 expression could be induced by hhi1 alone without the need for other viral genes. Our discovery should be useful for future mechanistic study of the switches of latent/productive HzNV-1 viral infections.
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Wu YL, Liu CYY, Wu CP, Wang CH, Lee ST, Chao YC. Cooperation of ie1 and p35 genes in the activation of baculovirus AcMNPV and HzNV-1 promoters. Virus Res 2008; 135:247-54. [PMID: 18486255 DOI: 10.1016/j.virusres.2008.04.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2008] [Revised: 04/01/2008] [Accepted: 04/01/2008] [Indexed: 11/17/2022]
Abstract
HzNV-1 is a non-occluded virus belongs to the family of the baculovirus. One of the first detectable transcripts expressed by HzNV-1 virus infection is a 6.2 kb gene, hhi1, located in the HindIII-I fragment of the viral genome. Here we show that infection of baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV) could activate the expression of the hhi1 promoter. By using constructs containing progressive deletions of the upstream regulatory regions of the hhi1 gene, we demonstrated that the most highly activated area was located between nucleotides -62 to +277 of the hhi1 promoter. We subsequently searched the entire 130 kb AcMNPV genome and identified two baculovirus genes, ie1 and p35, that their cooperation is required for the activation of the hhi1 promoter. Further, by taking advantages of a baculovirus DNA chip and low background baculovirus gene expressions in the mammalian cells, we went on to identify a specific set of baculoviral genes, including orf21 and orf25, that could be specifically activated by the combination of ie1 and p35 genes. We conclude that a unique cooperative mechanism of ie1 and p35 exists in the genome of AcMNPV, which can activate the expression of a specific set of AcMNPV and HzNV-1 promoters.
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Affiliation(s)
- Yueh-Lung Wu
- Institute of Biotechnology, National Cheng Kung University, No.1, University Road, Tainan 701, Taiwan
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9
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McIntosh AH, Grasela JJ, Ignoffo CM. In vitro host range of the Hz-1 nonoccluded virus in insect cell lines. In Vitro Cell Dev Biol Anim 2007; 43:196-201. [PMID: 17492336 DOI: 10.1007/s11626-007-9032-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2007] [Accepted: 04/10/2007] [Indexed: 10/23/2022]
Abstract
A total of 13 insect cell lines spanning 4 orders (Lepidoptera, Coleoptera, Diptera, and Homoptera) were tested for their ability to replicate the nonoccluded virus Hz-1. Only the Lepidopteran cell lines supported replication of the virus with TN-CL1 and BCIRL-HZ-AM1 producing the highest titers of 2.4 x 10(8) tissue culture infective dose (TCID)50/ml and 2.0 x 10(8) TCID50/ml, respectively. A codling moth cell line (CP-169) was the only Lepidopteran cell line that did not replicate the virus and transfection of this cell line with Hz-1 DNA failed to replicate the virus. Also, transfection with DNA from a recombinant baculovirus carrying the red fluorescent protein gene (AcMNPVhsp70 Red) was not expressed in CP-169 cells. The replication cycle of Hz-1 in BCIRL-HZ-AM1 cells showed that this virus replicated rapidly starting at 16 h postinoculation (p.i.) and reaching a peak titer of 1.0 x 10(8) TCID50/ml 56 h postinoculation. Hz-1 when compared with several other baculoviruses has the widest in vitro host spectrum.
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Affiliation(s)
- Arthur H McIntosh
- Agricultural Research Service, Biological Control of Insects Research Laboratory, United States Department of Agriculture, 1503 South Providence Road, Research Park, Columbia, MO 65203-3535, USA.
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10
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Cheng CH, Liu SM, Chow TY, Hsiao YY, Wang DP, Huang JJ, Chen HH. Analysis of the complete genome sequence of the Hz-1 virus suggests that it is related to members of the Baculoviridae. J Virol 2002; 76:9024-34. [PMID: 12186886 PMCID: PMC136428 DOI: 10.1128/jvi.76.18.9024-9034.2002] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2002] [Accepted: 06/06/2002] [Indexed: 11/20/2022] Open
Abstract
We report the complete sequence of a large rod-shaped DNA virus, called the Hz-1 virus. This virus persistently infects the Heliothis zea cell lines. The Hz-1 virus has a double-stranded circular DNA genome of 228,089 bp encoding 154 open reading frames (ORFs) and also expresses a persistence-associated transcript 1, PAT1. The G+C content of the Hz-1 virus genome is 41.8%, with a gene density of one gene per 1.47 kb. Sequence analysis revealed that a 9.6-kb region at 43.6 to 47.8 map units harbors five cellular genes encoding proteins with homology to dUTP pyrophosphatase, matrix metalloproteinase, deoxynucleoside kinase, glycine hydroxymethyltransferase, and ribonucleotide reductase large subunit. Other cellular homologs were also detected dispersed in the viral genome. Several baculovirus homologs were detected in the Hz-1 virus genome. These include PxOrf-70, PxOrf-29, AcOrf-81, AcOrf-96, AcOrf-22, VLF-1, RNA polymerase LEF-8 (orf50), and two structural proteins, p74 and p91. The Hz-1 virus p74 homolog shows high structural conservation with a double transmembrane domain at its C terminus. Phylogenetic analysis of the p74 revealed that the Hz-1 virus is evolutionarily distant from the baculoviruses. Another distinctive feature of the Hz-1 virus genome is a gene that is involved in insect development. However, the remainder of the ORFs (81%) encoded proteins that bear no homology to any known proteins. In conclusion, the sequence differences between the Hz-1 virus and the baculoviruses outnumber the similarities and suggest that the Hz-1 virus may form a new family of viruses distantly related to the Baculoviridae:
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Affiliation(s)
- Chia-Hsiung Cheng
- Institute of Biotechnology, National Cheng Kung University, Tainan 701, Taiwan
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11
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Guttieri MC, Buran JP. Location, nucleotide sequence, and regulation of the p51 late gene of the hz-1 insect virus: identification of a putative late regulatory element. Virus Genes 2002; 23:17-25. [PMID: 11556397 DOI: 10.1023/a:1011166926225] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
An Hz-1 insect virus (Hz-1V) late gene encoding, a predicted polypeptide of 51 kDa was isolated from a cDNA library and mapped to the HindIII-J region (40-44.6 map units) of the viral genome. The p51 gene was characterized by DNA sequence, Northern blot, and primer extension analyses. The 1,152 bp open reading frame (ORF) is transcribed as a 1.8 kb RNA between 8 and 18 h post-infection (hpi) with maximum expression at 12 hpi. Homology was not detected between the nucleotide sequence upstream of the p51 ORF and the baculovirus conserved late promoter element NTAAG. Primer extension analysis detected one major late transcription initiation site at -205 nucleotides relative to the start of the p51 ORF and seven minor late initiation sites at positions upstream of this primary site. Comparison of the upstream regulatory regions of the p51 gene and the Hz- 1V p34 late gene revealed a region of significant homology comprised of the 9 bp sequence TTATAGTAT. The primary p51 transcription initiation site and all p34 transcription initiation sites were mapped to different nucleotides within this nonanucleotide sequence. This 9 bp motif was not observed in the ORFs of these genes, and no significant homology was detected between this motif and the 5' regulatory regions of any other characterized genes. The results of our study suggest that this conserved sequence may serve an important role in the regulation of Hz-1V late genes.
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Affiliation(s)
- M C Guttieri
- Department of Microbiology, University of Massachusetts, Amherst 01003, USA
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12
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Chen HH, Tso DJ, Yeh WB, Cheng HJ, Wu TF. The thymidylate synthase gene of Hz-1 virus: a gene captured from its lepidopteran host. INSECT MOLECULAR BIOLOGY 2001; 10:495-503. [PMID: 11881814 DOI: 10.1046/j.0962-1075.2001.00289.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The sequence analysis of a thymidylate synthase gene was identified in the Hz-1 virus HindIII-D fragment. The viral thymidylate synthase gene encodes a protein of 295 amino acids, and is closely related to that of insect, mammals and herpesvirus. The thymidylate synthase gene identified was a genuine viral gene in that it was only detected in cells infected with Hz-1 virus but not in the mock infected cells, by Southern blot analysis and by RT-PCR. Results of phylogenetic analysis based on non-synonymous and amino acid distances suggested that the TS gene of Hz-1 virus was grouped closely with that of Bombyx mori. High bootstrap values confirmed that the thymidylate synthase of Hz-1 virus was acquired by a capture event from its lepidopteran host. Results of both sequence divergences and phylogenetic analysis suggested that TS genes in insect viruses, Hz-1, CIV, and MsEPV may have a different history or originated from different capture events.
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Affiliation(s)
- H H Chen
- Institute of Biotechnology, National Cheng Kung University, Tainan, Taiwan.
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Chen HH, Tsai FY, Chen CT. Negative regulatory regions of the PAT1 promoter of Hz-1 virus contain GATA elements which associate with cellular factors and regulate promoter activity. J Gen Virol 2001; 82:313-320. [PMID: 11161268 DOI: 10.1099/0022-1317-82-2-313] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The persistence-associated transcript 1 (PAT1) is actively expressed during persistent infection with Hz-1 virus, while transcription of the rest of the viral genes is shut down. Previously, results of a series deletion of the PAT1 promoter suggested that the regions from nucleotides -312 to -212 and nucleotides -158 to -90 negatively regulate the promoter activity. Here, the negative regulatory effect of the -312/-90 fragment was confirmed using a heterologous IE0 promoter of Autographa californica multiple nucleopolyhedrovirus. Further, the negative regulation of the -312 to -212 region was orientation-independent. The results of electrophoresis mobility shift assays showed that cellular protein(s) bind specifically to DNA fragments -312/-212 and -158/-90. In each of these fragments, a GATA element was identified by computer-assisted analysis. Mutating both GATA elements in the -312/-90 fragment completely eliminated its negative effect on IE0 promoter activity, while mutating only one of these elements had little or no effect. Together, these results suggest that the GATA element has a negative regulatory role on the IE0 and PAT1 promoters.
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Affiliation(s)
- Hong-Hwa Chen
- Institute of Biotechnology1 and Department of Biology2, National Cheng Kung University, Tainan 701, Taiwan
| | - Feng-Yuan Tsai
- Institute of Biotechnology1 and Department of Biology2, National Cheng Kung University, Tainan 701, Taiwan
| | - Chung-Te Chen
- Institute of Biotechnology1 and Department of Biology2, National Cheng Kung University, Tainan 701, Taiwan
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Lin CL, Lee JC, Chen SS, Wood HA, Li ML, Li CF, Chao YC. Persistent Hz-1 virus infection in insect cells: evidence for insertion of viral DNA into host chromosomes and viral infection in a latent status. J Virol 1999; 73:128-39. [PMID: 9847315 PMCID: PMC103816 DOI: 10.1128/jvi.73.1.128-139.1999] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Persistent/latent viral infections of insect cells are a prominent though poorly understood phenomenon. In this study, the long-term association between the Hz-1 virus and insect host cells, conventionally referred to as persistent viral infection, is described. With the aid of a newly developed fluorescent cell-labeling system, we found that productive viral replication occurs by spontaneous viral reactivation in fewer than 0.2% of persistently infected cell lines over a 5-day period. Once viral reactivation takes place, the host cell dies. The persistently infected cells contain various amounts of viral DNA, and, in an extreme case, up to 16% of the total DNA isolated from infected cells could be of viral origin. Both pulsed-field gel electrophoresis and in situ hybridization experiments showed that some of these viral DNA molecules are inserted into the host chromosomes but that the rest of viral DNA copies are free from host chromosomes. Thus, Hz-1 virus is the first nonretroviral insect virus known to insert its genome into the host chromosome during the infection process. These data also suggest that the previously described persistent infection of Hz-1 virus in insect cells should be more accurately referred to as latent viral infection.
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Affiliation(s)
- C L Lin
- Department of Biology, National Taiwan Normal University, Taipei 115, Taiwan, Republic of China
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Lee JC, Chen HH, Chao YC. Persistent baculovirus infection results from deletion of the apoptotic suppressor gene p35. J Virol 1998; 72:9157-65. [PMID: 9765462 PMCID: PMC110334 DOI: 10.1128/jvi.72.11.9157-9165.1998] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Infection with the wild-type baculovirus Autographa californica multiple nuclear polyhedrosis virus (AcMNPV) results in complete death of Spodoptera frugiperda (Sf) cells. However, infection of Sf cells with AcMNPV carrying a mutation or deletion of the apoptotic suppressor gene p35 allowed the cloning of surviving Sf cells that harbored persistent viral genomes. Persistent infection established with the virus with p35 mutated or deleted was blocked by stable transfection of p35 in the host genome or by insertion of the inhibitor of apoptosis (iap) gene into the viral genome. These artificially established persistently virus-infected cells became resistant to subsequent viral challenge, and some of the cell lines carried large quantities of viral DNA capable of early gene expression. Continuous release of viral progenies was evident in some of the persistently virus-infected cells, and transfection of p35 further stimulated viral activation of the persistent cells, including the reactivation of viruses in those cell lines without original continuous virus release. These results have demonstrated the successful establishment of persistent baculovirus infections under laboratory conditions and that their establishment may provide a novel continuous, nonlytic baculovirus expression system in the future.
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Affiliation(s)
- J C Lee
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 115, Taiwan, Republic of China
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16
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Chao YC, Lee ST, Chang MC, Chen HH, Chen SS, Wu TY, Liu FH, Hsu EL, Hou RF. A 2.9-kilobase noncoding nuclear RNA functions in the establishment of persistent Hz-1 viral infection. J Virol 1998; 72:2233-45. [PMID: 9499081 PMCID: PMC109520 DOI: 10.1128/jvi.72.3.2233-2245.1998] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Differential viral gene expression during both productive and persistent infections of Hz-1 virus in insect cells was elucidated. Despite more than 100 viral transcripts being expressed during productive viral infection, massive viral gene shutoff was observed during viral persistency, leaving the 2.9-kb persistence-associated transcript 1 (PAT1) as the only detectable viral RNA. Persistence-associated gene 1 (pag1), which encodes PAT1, was cloned and found to contain no significant open reading frames. PAT1 is not associated with the cellular translation machinery and is located exclusively in the nucleus. Further experiments showed that PAT1 is functional in the establishment of persistent Hz-1 viral infection in the cells. All the evidence collectively indicates that PAT1 is a novel nuclear transcript of viral origin. Our results showed that although PAT1 and XIST RNA, a mammalian X-inactive specific transcript, are transcribed by different genes, they have interesting similarities.
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Affiliation(s)
- Y C Chao
- Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan, Republic of China.
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18
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Lee ST, Yu SM, Hsu EL, Chao YC. Identification of a very early promoter of insect Hz-1 virus using a novel dual-expression shuttle vector. Nucleic Acids Res 1995; 23:4683-9. [PMID: 8524661 PMCID: PMC307444 DOI: 10.1093/nar/23.22.4683] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Very early promoters of viruses control the proper cascade expression of viral genes and are essential for completion of virus life cycles. These promoters are usually rare and weak and do not encode structural proteins. As a result, they are difficult to identify. In order to identify and clone the very early promoters of a large eukaryotic DNA virus, the Hz-1 virus, a novel cloning strategy was applied. This strategy is based on a dual-expression shuttle vector containing a promoter-less lacZ gene. Insertion of eukaryotic promoters upstream permits the efficient expression of LacZ in bacteria cells. The function of the putative promoters was then confirmed by their proper expression in insect cells. The first two productive infection-specific promoters of Hz-1 virus, contained within the shuttle vectors pTSV-2-129 and pTSV-2-49, were cloned from the HindIII-K and HindIII-A fragments of the Hz-1 viral genome, respectively. By primer extension analysis, an immediate and constitutive expression of the promoter in clone pTSV-2-129 was detected after viral infection. Identification of the productive infection-specific promoters has laid down important groundwork for future studies on the molecular mechanism of the transcriptional switch between productive and persistent infections of Hz-1 virus.
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Affiliation(s)
- S T Lee
- Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan, Republic of China
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Lee JC, Chen HH, Wei HL, Chao YC. Superinfection-induced apoptosis and its correlation with the reduction of viral progeny in cells persistently infected with Hz-1 baculovirus. J Virol 1993; 67:6989-94. [PMID: 8230422 PMCID: PMC238158 DOI: 10.1128/jvi.67.12.6989-6994.1993] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Differential induction of necrosis or apoptosis was found upon challenge of cells of the insect Spodoptera frugiperda productively or persistently infected with Hz-1 baculovirus, respectively. Unlike parental SF9 cells, which were essentially all killed by virally induced necrosis, persistently infected cells underwent a process of massive cell death by apoptosis; cells which were not killed by apoptosis then reestablished a cell monolayer. Upon viral challenge, the yield of viral progeny was reduced greatly in persistently virus-infected cells but not in parental cells. Immunolabelling of individual cells revealed that upon viral challenge, production of viral progeny was detectable only in necrotic cells and not in apoptotic cells. These results indicated that induction of apoptosis greatly reduces the yield of viral progeny in cells persistently infected with Hz-1 baculovirus. This is the first report of apoptosis induction in persistently infected cells upon viral superinfection.
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Affiliation(s)
- J C Lee
- Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan, Republic of China
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Chao YC, Wood HA, Chang CY, Lee HJ, Shen WC, Lee HT. Differential expression of Hz-1 baculovirus genes during productive and persistent viral infections. J Virol 1992; 66:1442-8. [PMID: 1738201 PMCID: PMC240868 DOI: 10.1128/jvi.66.3.1442-1448.1992] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Hz-1 viral RNA transcription was studied during productive and persistent infections. The RNAs were localized to 10- to 30-kb regions within the viral genome, and the timing of their expression was determined. During productive infections, we detected 101 virus-specific transcripts that could be grouped into three categories by time of appearance. At 2 h postinoculation (p.i.), a total of 34 virus-specific transcripts were detected. An additional 51 and 16 virus-specific transcripts appeared between 4 and 6 h p.i. and at 8 h p.i., respectively. After 8 h, no new transcripts were found. Under conditions of persistent infection, we detected only one viral persistency-associated transcript (PAT1). The region of the viral DNA which encodes PAT1 was cloned. During productive infections, three transcripts were derived from this region. Each had the same polarity as PAT1. One of them was of the same size as PAT1 and had similar, if not identical, 3' and 5' ends. This report provides detailed and very useful information concerning sequentially expressed transcripts of the Hz-1 baculovirus.
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Affiliation(s)
- Y C Chao
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, Republic of China
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Cherry CL, Summers MD. Genotypic variation among wild isolates of two nuclear polyhedrosis viruses isolated from Spodoptera littoralis. J Invertebr Pathol 1985. [DOI: 10.1016/0022-2011(85)90071-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Exploring the Gene Organization of Baculoviruses. ACTA ACUST UNITED AC 1984. [DOI: 10.1016/b978-0-12-470207-3.50014-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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