Ascoviruses: Superb Manipulators of Apoptosis for Viral Replication and Transmission

Federici, Brian A.; Bideshi, Dennis K.; Tan, Yeping; Spears, Tatsinda; Bigot, Yves

doi:10.1007/978-3-540-68618-7_5

Cited by 34 publications

(42 citation statements)

References 40 publications

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“…Genome sequences (119-to 187-kbp dsDNA) of four recognized AV species, Spodoptera frugiperda AV (SfAV-1), Trichoplusia ni AV (TnAV-2), Heliothis virescens AV (HvAV-3), and Diadromus pulchellus AV (DpAV-4) are now available (1,4,6,30). Phylogenetic studies suggest that AVs may have evolved from iridoviruses that infect lepidopteran larvae (15,29). There are 180 potential ORFs in the HvAV-3e genome, most of which are homologs to genes involved in nucleic acid metabolism, virus replication, apoptosis, and lipid metabolism (1).…”

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confidence: 99%

An Ascovirus-Encoded RNase III Autoregulates Its Expression and Suppresses RNA Interference-Mediated Gene Silencing

Hussain

Abraham

Asgari

2010

J Virol

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RNase III proteins play vital roles in processing of several types of RNA molecules and gene silencing. Recently, it has been discovered that some plant and animal viruses encode RNase III-like proteins as well. Genome sequencing of four virus species belonging to the Ascoviridae family has revealed sequence conservation of an RNase III open reading frame among the viruses. These have not been explored in ascoviruses, and therefore their role in host-virus interaction is unknown. Here, we confirmed expression of Heliothis virescens ascovirus (HvAV-3e) open reading frame 27 (orf27) that encodes an RNase III-like protein after infection and demonstrated dsRNA specific endoribonuclease activity of the encoded protein. Analysis of the expression patterns of orf27 in virus-infected insect cells and a bacterial expression system revealed autoregulation of this protein over time. Moreover, HvAV-3e RNase III was found essential for virus DNA replication and infection using RNA interference (RNAi)-mediated gene silencing. In addition, using green fluorescent protein gene as a marker, we provide evidence that RNase III is involved in the suppression of gene silencing. To our knowledge, this is the first insect virus-encoded RNase III described and shown to suppress host cell RNAi defense mechanism.

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confidence: 99%

An Ascovirus-Encoded RNase III Autoregulates Its Expression and Suppresses RNA Interference-Mediated Gene Silencing

Hussain

Abraham

Asgari

2010

J Virol

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“…Larval molting is another index reflecting changes in hormone balance induced by HvAV-3h or even reflecting larval metabolism during growing stages [19,34,35]. HvAV-3h is able to alter larval molting period, this is another important feature of AV infection in larvae [14,19]. In H. armigera , in contrast to the untreated control larvae, most H. armigera larvae showed an extended larval instar period, over 3 days in average (Table 3).…”

Section: Discussionmentioning

confidence: 99%

“…The virion shape is similar to baculoviruses but more variable, from bacilliform to ovoid or allantoid [7,13]. Indeed, the virion shape and the hemolymph vesicles aid in ascovirus identification [14]. …”

Section: Introductionmentioning

confidence: 99%

A Comparison of Growth and Development of Three Major Agricultural Insect Pests Infected with Heliothis virescens ascovirus 3h (HvAV-3h)

Wang

Zhou

et al. 2013

PLoS ONE

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Ascoviruses are double-stranded DNA viruses that are pathogenic to lepidopteran hosts, particularly noctuid larvae. Infection of a larva is characterized by retarded growth, reduced feeding and yellowish body color. In this paper, we reported the growth and development of three major agricultural noctuid insect pests, Helicoverpa armigera (Hübner), Spodoptera exigua (Hübner) and Spodoptera litura (Fabricius), infected with Heliothis virescens ascovirus 3h (HvAV-3h). Using 10-fold serial dilutions (0 to 7) of HvAV-3h-containing hemolymph to infect S. litura larvae, we found no significant difference in larval mortalities from 0 to 103-fold dilutions; however, significant differences were observed at 104-fold dilution and above. Using a 10-fold dilution of HvAV-3h-containing hemolymph to infect H. armigera, S. exigua and S. litura larvae, we found that the growth and development were significantly affected. All infected larvae could not pupate; the survival times of treated H. armigera, S. litura and S. exigua larvae were significantly longer than untreated control larvae. Body weight showed significant difference between treated and untreated control group from day 1 after inoculation in H. armigera and S. exigua, but day 2 in S. litura. Additionally, food intake also showed significant difference between treated and untreated control group from day 2 after inoculation in H. armigera and S. litura, but day 3 in S. exigua.

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“…These viruses possess a single circular double-stranded DNA genome ranging from 119 to 186 kbp and is encapsidated in virions of allantoid to bacilliform shapes (10). There are four recognized AV species, Spodoptera frugiperda AV (SfAV-1), Trichoplusia ni AV (TnAV-2), Heliothis virescens AV (HvAV-3), and Diadromus pulchellus AV (DpAV-4), and their complete genome sequences now are available (1)(2)(3)31).…”

mentioning

confidence: 99%

“…The salient changes in cell morphology upon AV infection start with the enlargement and breakdown of nuclei, leading to the fragmentation of cells and vesicle formation. These vesicles are disseminated in the hemocoel and produce milky white hemolymph, which results in the death of the host insect (10). They encode three predicted proteins with homology to eukaryotic RNA polymerase RPC1, RPC2, and ␤ subunits.…”

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confidence: 99%

Functional Analysis of a Cellular MicroRNA in Insect Host-Ascovirus Interaction

Hussain

Asgari

2010

J Virol

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MicroRNAs (miRNAs) have emerged as key regulators in many biological processes, from development to defense, at almost all organismal levels. Recently, their role has been highlighted in pathogen-host interactions. Emerging evidence from a variety of virus-host systems indicates that cellular as well as virally encoded miRNAs influence viral replication. Here, we report changes in expression levels of host miRNAs upon ascovirus infection in an insect cell line and investigated the role of a host miRNA, Hz-miR24, in the host-virus system. We found that Hz-miR24 is differentially expressed following virus infection, with an increase in its expression levels late in infection. Experimental evidence demonstrated that Hz-miR24 downregulates ascoviral DNA-dependent RNA polymerase and its ␤ subunit transcript levels late in infection. The specific miRNA-target interactions were investigated and confirmed using the ectopic expression of Hz-miR24 and a green fluorescent protein-based reporter system. Further, the expression of the target gene was substantially enhanced in cells transfected with a synthesized inhibitor of Hz-miR24. These findings suggest that ascoviruses manipulate host miRNAs that in turn regulate the expression of their genes at specific time points after infection. To our knowledge, this is the first cellular miRNA reported to interact with an insect virus.

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Ascoviruses: Superb Manipulators of Apoptosis for Viral Replication and Transmission

Cited by 34 publications

References 40 publications

An Ascovirus-Encoded RNase III Autoregulates Its Expression and Suppresses RNA Interference-Mediated Gene Silencing

An Ascovirus-Encoded RNase III Autoregulates Its Expression and Suppresses RNA Interference-Mediated Gene Silencing

A Comparison of Growth and Development of Three Major Agricultural Insect Pests Infected with Heliothis virescens ascovirus 3h (HvAV-3h)

Functional Analysis of a Cellular MicroRNA in Insect Host-Ascovirus Interaction

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