Frog virus 3 requires RNA polymerase II for its replication

Goorha, Rakesh

doi:10.1128/jvi.37.1.496-499.1981

Cited by 58 publications

(19 citation statements)

References 16 publications

(8 reference statements)

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“…The two-stage sequence of FV3 DNA replication and processing of concatemers can be integrated with previous findings (6,8,9) to provide a scheme of replication that contrasts sharply with the replication strategies of most animal viruses (Fig. 8).…”

Section: Resultsmentioning

confidence: 74%

“…Originally believed to replicate only in the cytoplasm (12), FV3 has since been shown to require a functional nucleus for its replication (9). Recent work has shown that the FV3 genome enters the nucleus, where it is transcribed during early stages of replication (8) probably by a modified host RNA polymerase II (6). Although the viral DNA replicates in both the nucleus and the cytoplasm (8), virus assembly and morphogenesis take place only in the cytoplasm (7,12).…”

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confidence: 99%

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Frog Virus 3 DNA Replication Occurs in Two Stages

Goorha

1982

J Virol

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Viral DNA synthesis in frog virus 3 (FV3)-infected cells occurs both in the nucleus and in the cytoplasm (Goorha et al., Virology 84 :32-51, 1978). Relationships between viral DNA molecules synthesized in these two compartments and their role in the virus replication were examined. The data presented here suggest that (i) FV3 DNA replicated in two stages and (ii) nucleus and cytoplasm were the sites of stages 1 and 2 of DNA replication, respectively. Stages 1 and 2 were further distinguished by their temporal appearance during infection and by the sizes of the replicating DNA as determined by sedimentation in neutral sucrose gradients. In stage 1, replicating molecules, between the size of unit and twice the unit length, were produced early in infection (2 h postinfection). In contrast, stage 2 of DNA replication occurred only after 3 h postinfection, and replicating molecules were large concatemers. Results of pulse-chase experiments showed that the concatemeric DNA served as the precursor for the production of mature FV3 DNA. Denaturation of concatemeric DNA with alkali or digestion with S1 nuclease reduced it to less than genome size molecules, indicating the presence of extensive single-stranded regions. Analysis of replicating DNA by equilibrium centrifugation in CsCl gradients after a pulse-chase suggested that these single-stranded regions were subsequently repaired. Based on these and previous data, a scheme of FV3 replication is presented. According to this scheme, FV3 utilizes the nucleus for early transcription and stage 1 of DNA replication. The viral DNA is then transported to the cytoplasm, where it participates in stage 2 DNA replication to form a concatemeric replication complex. The processing of concatemers to produce mature viral DNA and virus assembly also occurs in the cytoplasm. This mode of replication is strikingly different from any other known DNA virus.

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Section: Resultsmentioning

confidence: 74%

mentioning

confidence: 99%

Frog Virus 3 DNA Replication Occurs in Two Stages

Goorha

1982

J Virol

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“…Unlike herpesviruses, iridovirid genomes are not infectious, indicating that virion-associated proteins are required to initiate viral gene transcription [32]. Accordingly, immediate-early (IE) and delayed early (DE) viral transcripts are synthesized in reactions mediated by putative virion-associated (for IE transcripts) and virus-encoded (for DE mRNA) transcriptional trans-activators and, at least for IE transcription, host RNA polymerase II [33][34][35]. Among the products of early transcription is a viral DNA polymerase which catalyzes the synthesis of unit-sized copies of the viral genome within the nucleus [36].…”

Section: Early Events/nuclear Phasementioning

confidence: 99%

The Molecular Biology of Frog Virus 3 and other Iridoviruses Infecting Cold-Blooded Vertebrates

Chinchar

Jancovich

2011

Viruses

106

103

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Frog virus 3 (FV3) is the best characterized member of the family Iridoviridae. FV3 study has provided insights into the replication of other family members, and has served as a model of viral transcription, genome replication, and virus-mediated host-shutoff. Although the broad outlines of FV3 replication have been elucidated, the precise roles of most viral proteins remain unknown. Current studies using knock down (KD) mediated by antisense morpholino oligonucleotides (asMO) and small, interfering RNAs (siRNA), knock out (KO) following replacement of the targeted gene with a selectable marker by homologous recombination, ectopic viral gene expression, and recombinant viral proteins have enabled researchers to systematically ascertain replicative- and virulence-related gene functions. In addition, the application of molecular tools to ecological studies is providing novel ways for field biologists to identify potential pathogens, quantify infections, and trace the evolution of ecologically important viral species. In this review, we summarize current studies using not only FV3, but also other iridoviruses infecting ectotherms. As described below, general principles ascertained using FV3 served as a model for the family, and studies utilizing other ranaviruses and megalocytiviruses have confirmed and extended our understanding of iridovirus replication. Collectively, these and future efforts will elucidate molecular events in viral replication, intrinsic and extrinsic factors that contribute to disease outbreaks, and the role of the host immune system in protection from disease.

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“…A few FV3 promoters methylated in all 5'-CG-3' dinucleotides have been directly shown to be transcriptionally active [40][41][42] Host RNA polymerase II is thought to be utilized for FV3 mRNA synthesis. 43 Since this polymerase and many of the known cellular transcription factors can be inhibited by promoter methylation, the major question arises of what factors might be involved in keeping the fully 5'-CG-3' methylated FV3 promoters transcriptionally active.…”

Section: Synopsis Of Studies On Dna Methylationmentioning

confidence: 99%

In pursuit of the first recognized epigenetic signal––DNA methylation: A 1976 to 2008 synopsis

Doerfler

2008

Epigenetics

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A synopsis will be presented of work on DNA methylation, the first epigenetic signal to be recognized. In the author's laboratory, the following problems dealing with DNA methylation have been addressed over the past 32 years: (1) The de novo methylation of foreign DNA integrated into mammalian genomes. (2) Inverse correlations between promoter methylation and activity. (3) The long-term inactivating effect of site-specific promoter methylation. (4) Adenovirus E1 functions in trans and a strong enhancer in cis cancel the silencing effect of promoter methylation. (5) Frog virus 3, an iridovirus with a completely CpG-methylated genome. (6) Mechanisms of de novo methylation. (7) Different segments of the genome possess topical methylation memories. (8) Consequences of foreign DNA insertion into mammalian genomes: alterations of DNA methylation in cis and trans. (9) The epigenetic status of an adenovirus transgenome in Ad12-transformed hamster cells. (10) Cell type-specific patterns of DNA methylation: interindividual concordance in the human genome.

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Frog virus 3 requires RNA polymerase II for its replication

Cited by 58 publications

References 16 publications

Frog Virus 3 DNA Replication Occurs in Two Stages

Frog Virus 3 DNA Replication Occurs in Two Stages

The Molecular Biology of Frog Virus 3 and other Iridoviruses Infecting Cold-Blooded Vertebrates

In pursuit of the first recognized epigenetic signal––DNA methylation: A 1976 to 2008 synopsis

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