scholarly journals Dangerous Liaisons: Long-Term Replication with an Extrachromosomal HPV Genome

Viruses ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1846
Author(s):  
Alix Warburton ◽  
Ashley N. Della Fera ◽  
Alison A. McBride
Keyword(s):  
Viral Genome ◽  
Copy Number ◽  
Close Association ◽  
Viral Dna ◽  
Dna Damage And Repair ◽  
Cellular Processes ◽  
Low Copy Number ◽  
Infected Cells ◽  
Cellular Replication ◽  
Host Epithelium

Papillomaviruses cause persistent, and usually self-limiting, infections in the mucosal and cutaneous surfaces of the host epithelium. However, in some cases, infection with an oncogenic HPV can lead to cancer. The viral genome is a small, double-stranded circular DNA molecule that is assembled into nucleosomes at all stages of infection. The viral minichromosome replicates at a low copy number in the nucleus of persistently infected cells using the cellular replication machinery. When the infected cells differentiate, the virus hijacks the host DNA damage and repair pathways to replicate viral DNA to a high copy number to generate progeny virions. This strategy is highly effective and requires a close association between viral and host chromatin, as well as cellular processes associated with DNA replication, repair, and transcription. However, this association can lead to accidental integration of the viral genome into host DNA, and under certain circumstances integration can promote oncogenesis. Here we describe the fate of viral DNA at each stage of the viral life cycle and how this might facilitate accidental integration and subsequent carcinogenesis.

scholarly journals The UL25 Gene Product of Herpes Simplex Virus Type 1 Is Involved in Uncoating of the Viral Genome

2008 ◽  
Vol 82 (13) ◽  
pp. 6654-6666 ◽  
Author(s):  
Valerie G. Preston ◽  
Jill Murray ◽  
Christopher M. Preston ◽  
Iris M. McDougall ◽  
Nigel D. Stow
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Herpes Simplex Virus Type ◽  
Viral Genome ◽  
Dna Packaging ◽  
Nonpermissive Temperature ◽  
Viral Dna ◽  
Infected Cells ◽  
Simplex Virus

ABSTRACT Studies on the herpes simplex virus type 1 UL25-null mutant KUL25NS have shown that the capsid-associated UL25 protein is required at a late stage in the encapsidation of viral DNA. Our previous work on UL25 with the UL25 temperature-sensitive (ts) mutant ts1204 also implicated UL25 in a role at very early times in the virus growth cycle, possibly at the stage of penetration of the host cell. We have reexamined this mutant and discovered that it had an additional ts mutation elsewhere in the genome. The ts1204 UL25 mutation was transferred into wild-type (wt) virus DNA, and the UL25 mutant ts1249 was isolated and characterized to clarify the function of UL25 at the initial stages of virus infection. Indirect immunofluorescence assays and in situ hybridization analysis of virus-infected cells revealed that the mutant ts1249 was not impaired in penetration of the host cell but had an uncoating defect at the nonpermissive temperature. When ts1249-infected cells were incubated initially at the permissive temperature to allow uncoating of the viral genome and subsequently transferred to the restrictive temperature, a DNA-packaging defect was evident. The results suggested that ts1249, like KUL25NS, had a block at a late stage of DNA packaging and that the packaged genome was shorter than the full-length genome. Examination of ts1249 capsids produced at the nonpermissive temperature revealed that, in comparison with wt capsids, they contained reduced amounts of UL25 protein, thereby providing a possible explanation for the failure of ts1249 to package full-length viral DNA.

scholarly journals Virus DNA Replication and the Host DNA Damage Response

2018 ◽  
Vol 5 (1) ◽  
pp. 141-164 ◽  
Author(s):  
Matthew D. Weitzman ◽  
Amélie Fradet-Turcotte
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Life Cycles ◽  
Dynamic Interactions ◽  
Dna Damage And Repair ◽  
Dna Viruses ◽  
Cellular Processes ◽  
Damage Response ◽  
Cellular Replication ◽  
Cellular Dna

Viral DNA genomes have limited coding capacity and therefore harness cellular factors to facilitate replication of their genomes and generate progeny virions. Studies of viruses and how they interact with cellular processes have historically provided seminal insights into basic biology and disease mechanisms. The replicative life cycles of many DNA viruses have been shown to engage components of the host DNA damage and repair machinery. Viruses have evolved numerous strategies to navigate the cellular DNA damage response. By hijacking and manipulating cellular replication and repair processes, DNA viruses can selectively harness or abrogate distinct components of the cellular machinery to complete their life cycles. Here, we highlight consequences for viral replication and host genome integrity during the dynamic interactions between virus and host.

scholarly journals The Essential Human Cytomegalovirus Gene UL52 Is Required for Cleavage-Packaging of the Viral Genome

2007 ◽  
Vol 82 (5) ◽  
pp. 2065-2078 ◽  
Author(s):  
Eva Maria Borst ◽  
Karen Wagner ◽  
Anne Binz ◽  
Beate Sodeik ◽  
Martin Messerle
Keyword(s):  
Human Cytomegalovirus ◽  
Viral Genome ◽  
Essential Role ◽  
Unit Length ◽  
Viral Dna ◽  
Subnuclear Localization ◽  
Viral Genomes ◽  
Nuclear Egress ◽  
C Terminus ◽  
Infected Cells

ABSTRACT Replication of human cytomegalovirus (HCMV) produces large DNA concatemers of head-to-tail-linked viral genomes that upon packaging into capsids are cut into unit-length genomes. The mechanisms underlying cleavage-packaging and the subsequent steps prior to nuclear egress of DNA-filled capsids are incompletely understood. The hitherto uncharacterized product of the essential HCMV UL52 gene was proposed to participate in these processes. To investigate the function of pUL52, we constructed a ΔUL52 mutant as well as a complementing cell line. We found that replication of viral DNA was not impaired in noncomplementing cells infected with the ΔUL52 virus, but viral concatemers remained uncleaved. Since the subnuclear localization of the known cleavage-packaging proteins pUL56, pUL89, and pUL104 was unchanged in ΔUL52-infected fibroblasts, pUL52 does not seem to act via these proteins. Electron microscopy studies revealed only B capsids in the nuclei of ΔUL52-infected cells, indicating that the mutant virus has a defect in encapsidation of viral DNA. Generation of recombinant HCMV genomes encoding epitope-tagged pUL52 versions showed that only the N-terminally tagged pUL52 supported viral growth, suggesting that the C terminus is crucial for its function. pUL52 was expressed as a 75-kDa protein with true late kinetics. It localized preferentially to the nuclei of infected cells and was found to enclose the replication compartments. Taken together, our results demonstrate an essential role for pUL52 in cleavage-packaging of HCMV DNA. Given its unique subnuclear localization, the function of pUL52 might be distinct from that of other cleavage-packaging proteins.

Mechanisms and strategies of papillomavirus replication

2017 ◽  
Vol 398 (8) ◽  
pp. 919-927 ◽  
Author(s):  
Alison A. McBride
Keyword(s):  
Human Papillomaviruses ◽  
Complex Life Cycle ◽  
Progeny Virus ◽  
Viral Dna ◽  
Viral Dna Replication ◽  
Viral Genomes ◽  
Cellular Processes ◽  
Dividing Cells ◽  
Infected Cells ◽  
Low Levels

Abstract Animal and human papillomaviruses (HPVs) replicate persistently in specific types of stratified epithelia of their host. After the initial infection, the viral genome replicates at low levels in the dividing cells of the epithelium, and these cells form a reservoir of infection that can last for decades. When the infected cells differentiate, viral genomes replicate to high levels to form progeny virus that is released from the surface of the epithelium. This complex life cycle requires several different modes of viral DNA replication, but papillomaviruses are masters at hijacking key cellular processes to facilitate their own reproduction.

scholarly journals Morphological, Biochemical, and Functional Study of Viral Replication Compartments Isolated from Adenovirus-Infected Cells

2016 ◽  
Vol 90 (7) ◽  
pp. 3411-3427 ◽  
Author(s):  
Paloma Hidalgo ◽  
Lourdes Anzures ◽  
Armando Hernández-Mendoza ◽  
Adán Guerrero ◽  
Christopher D. Wood ◽  
...  
Keyword(s):  
Viral Replication ◽  
Host Cell ◽  
Viral Genome ◽  
Molecular Mechanisms ◽  
De Novo ◽  
Functional Study ◽  
Viral Dna ◽  
Superresolution Microscopy ◽  
Infected Cells ◽  
Efficient Viral Replication

ABSTRACTAdenovirus (Ad) replication compartments (RC) are nuclear microenvironments where the viral genome is replicated and a coordinated program of late gene expression is established. These virus-induced nuclear sites seem to behave as central hubs for the regulation of virus-host cell interactions, since proteins that promote efficient viral replication as well as factors that participate in the antiviral response are coopted and concentrated there. To gain further insight into the activities of viral RC, here we report, for the first time, the morphology, composition, and activities of RC isolated from Ad-infected cells. Morphological analyses of isolated RC particles by superresolution microscopy showed that they were indistinguishable from RC within infected cells and that they displayed a dynamic compartmentalization. Furthermore, the RC-containing fractions (RCf) proved to be functional, as they directedde novosynthesis of viral DNA and RNA as well as RNA splicing, activities that are associated with RCin vivo. A detailed analysis of the production of viral late mRNA from RCf at different times postinfection revealed that viral mRNA splicing occurs in RC and that the synthesis, posttranscriptional processing, and release from RC to the nucleoplasm of individual viral late transcripts are spatiotemporally separate events. The results presented here demonstrate that RCf are a powerful system for detailed study into RC structure, composition, and activities and, as a result, the determination of the molecular mechanisms that induce the formation of these viral sites of adenoviruses and other nuclear-replicating viruses.IMPORTANCERC may represent molecular hubs where many aspects of virus-host cell interaction are controlled. Here, we show by superresolution microscopy that RCf have morphologies similar to those of RC within Ad-infected cells and that they appear to be compartmentalized, as nucleolin and DBP display different localization in the periphery of these viral sites. RCf proved to be functional, as they directde novosynthesis of viral DNA and mRNA, allowing the detailed study of the regulation of viral genome replication and expression. Furthermore, we show that the synthesis and splicing of individual viral late mRNA occurs in RC and that they are subject to different temporal patterns of regulation, from their synthesis to their splicing and release from RC to the nucleoplasm. Hence, RCf represent a novel system to study molecular mechanisms that are orchestrated in viral RC to take control of the infected cell and promote an efficient viral replication cycle.

scholarly journals Human Cytomegalovirus Replicates Abortively in Polymorphonuclear Leukocytes after Transfer from Infected Endothelial Cells via Transient Microfusion Events

2000 ◽  
Vol 74 (12) ◽  
pp. 5629-5638 ◽  
Author(s):  
Giuseppe Gerna ◽  
Elena Percivalle ◽  
Fausto Baldanti ◽  
Silvano Sozzani ◽  
Paolo Lanzarini ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Human Cytomegalovirus ◽  
Copy Number ◽  
Polymorphonuclear Leukocytes ◽  
Biologically Active ◽  
Lung Fibroblasts ◽  
Wild Type ◽  
Viral Dna ◽  
Infected Cells ◽  
Type Strains

ABSTRACT Using a recently developed model for in vitro generation of pp65-positive polymorphonuclear leukocytes (PMNLs), we demonstrated that PMNLs from immunocompetent subjects may harbor both infectious human cytomegalovirus (HCMV) and viral products (pp65, p72, DNA, and immediate-early [IE] and pp67 late mRNAs) as early as 60 min after coculture with human umbilical vein endothelial cells (HUVEC) or human embryonic lung fibroblasts (HELF) infected with a clinical HCMV isolate (VR6110) or other wild-type strains. The number of PMNLs positive for each viral parameter increased with coculture time. Using HELF infected with laboratory-adapted HCMV strains, only very small amounts of viral DNA and IE and late mRNAs were detected in PMNLs. A cellular mRNA, the vascular cell adhesion molecule-1 mRNA, which is abundantly present in both infected and uninfected HUVEC, was detected in much larger amounts in PMNLs cocultured with VR6110-infected cells than in controls. Coculture of PMNLs with VR6110-infected permissive cells in the presence or absence of RNA, protein, and viral DNA synthesis inhibitors showed that only IE genes were transcribed in PMNLs during coculture. Synthesis of IE transcripts in PMNLs was also supported by the finding that only the copy number of IE mRNA (and not the DNA or the pp67 mRNA) per infected PMNL increased markedly with time, and the pp67 to IE mRNA copy number ratio changed from greater than 10 in infected HUVEC to less than 1 in cocultured PMNLs. Fluorescent probe transfer experiments and electron microscopy studies indicated that transfer of infectious virus and viral products from infected cells to PMNLs is likely to be mediated by microfusion events induced by wild-type strains only. In addition, HCMV pp65 and p72 were both shown to localize in the nucleus of the same PMNLs by double immunostaining. Two different mechanisms may explain the virus presence in PMNLs: (i) one major mechanism consists of transitory microfusion events (induced by wild-type strains only) of HUVEC or HELF and PMNLs with transfer of viable virus and biologically active viral material to PMNLs; and (ii) one minor mechanism, i.e., endocytosis, occurs with both wild-type and laboratory strains and leads to the acquisition of very small amounts of viral nucleic acids. In conclusion, HCMV replicates abortively in PMNLs, and wild-type strains and their products (as well as cellular metabolites and fluorescent dyes) are transferred to PMNLs, thus providing evidence for a potential mechanism of HCMV dissemination in vivo.

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