Immunosuppression induced by expression of a viral RNase enhances susceptibility of <i>Plutella xylostella</i> to microbial pesticides

Park, Bokri; Kim, Yonggyun

doi:10.1111/j.1744-7917.2011.01421.x

Cited by 9 publications

(6 citation statements)

References 44 publications

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“…Ribonucleases of the T2 family (RNase T2) are ubiquitous cellular enzymes that non-specifically cleave ssRNA in acidic environments [ 138 ]. DNA polydnaviruses and RNA pestiviruses are the only two other virus groups that are known to encode related enzymes [ 139 , 140 ]. In pestiviruses, the RNase T2 homolog is a domain of secreted glycoprotein E rns found in virions, but dispensable for virus entry [ 141 ].…”

Section: Discussionmentioning

confidence: 99%

“…None of these residues were found in the PSCNV RNase T2 homolog, consistent with its location in the polyprotein region that produces cytoplasmic proteins in other nidoviruses. In polydnaviruses and pestiviruses, the RNase T2 homolog modulates cell toxicity and immunity [ 139 , 140 ], and a similar role could be considered for the PSCNV RNase T2 homolog. The origin of this domain in PSCNV remains uncertain due to the lack of close homologs in either its host, S .…”

Section: Discussionmentioning

confidence: 99%

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A planarian nidovirus expands the limits of RNA genome size

et al. 2018

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RNA viruses are the only known RNA-protein (RNP) entities capable of autonomous replication (albeit within a permissive host environment). A 33.5 kilobase (kb) nidovirus has been considered close to the upper size limit for such entities; conversely, the minimal cellular DNA genome is in the 100–300 kb range. This large difference presents a daunting gap for the transition from primordial RNP to contemporary DNA-RNP-based life. Whether or not RNA viruses represent transitional steps towards DNA-based life, studies of larger RNA viruses advance our understanding of the size constraints on RNP entities and the role of genome size in virus adaptation. For example, emergence of the largest previously known RNA genomes (20–34 kb in positive-stranded nidoviruses, including coronaviruses) is associated with the acquisition of a proofreading exoribonuclease (ExoN) encoded in the open reading frame 1b (ORF1b) in a monophyletic subset of nidoviruses. However, apparent constraints on the size of ORF1b, which encodes this and other key replicative enzymes, have been hypothesized to limit further expansion of these viral RNA genomes. Here, we characterize a novel nidovirus (planarian secretory cell nidovirus; PSCNV) whose disproportionately large ORF1b-like region including unannotated domains, and overall 41.1-kb genome, substantially extend the presumed limits on RNA genome size. This genome encodes a predicted 13,556-aa polyprotein in an unconventional single ORF, yet retains canonical nidoviral genome organization and expression, as well as key replicative domains. These domains may include functionally relevant substitutions rarely or never before observed in highly conserved sites of RdRp, NiRAN, ExoN and 3CLpro. Our evolutionary analysis suggests that PSCNV diverged early from multi-ORF nidoviruses, and acquired additional genes, including those typical of large DNA viruses or hosts, e.g. Ankyrin and Fibronectin type II, which might modulate virus-host interactions. PSCNV's greatly expanded genome, proteomic complexity, and unique features–impressive in themselves–attest to the likelihood of still-larger RNA genomes awaiting discovery.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

A planarian nidovirus expands the limits of RNA genome size

et al. 2018

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“…S6). Pestivirus and polydnavirus ribonuclease T2 homologs modulate cell toxicity and immunity (40,41).…”

Section: Resultsmentioning

confidence: 99%

A planarian nidovirus expands the limits of RNA genome size

Saberi

Gulyaeva

Brubacher

et al. 2018

Preprint

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RNA viruses are the only known RNA-protein (RNP) entities capable of autonomous replication (albeit within a permissive environment). A 33.5-kb nidovirus has been considered close to the upper size limit for such entities; conversely, the minimal cellular DNA genome is ~200 kb. This large difference presents a daunting gap for the transition from primordial RNP to contemporary DNA-RNP-based life. Whether or not RNA viruses represent transitional steps on the road to DNA-based life, studies of larger RNA viruses advance our understanding of size constraints on RNP entities. For example, emergence of the largest previously known RNA genomes (20-34 kb in positive-stranded nidoviruses, including coronaviruses) is associated with a proofreading exoribonuclease encoded in the nidoviral open reading frame 1b (ORF1b). However, apparent constraints on the size of ORF1b, which encodes this and other key replicative enzymes, have been hypothesized to limit further expansion of viral RNA genomes. Here, we characterize a novel nidovirus (planarian secretory cell nidovirus; PSCNV) whose disproportionately large ORF1b-like region, and overall 41.1 kb genome, substantially extend the presumed limits on RNA genome size. This genome encodes a predicted 13,556-aa polyprotein in an unconventional single ORF, yet retains canonical nidoviral genome organization and expression, and key replicative domains. Our evolutionary analysis suggests that PSCNV diverged early from multi-ORF nidoviruses, and subsequently acquired additional genes, including those typical of large DNA viruses or hosts. PSCNV's greatly expanded genome, proteomic complexity, and unique featuresimpressive in themselvesattest to the likelihood of still-larger RNA genomes awaiting discovery. author/funder. All rights reserved. No reuse allowed without permission.The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/299776 doi: bioRxiv preprint Significance StatementRNA viruses are the only known RNA-protein (RNP) entities capable of autonomous replication. The upper genome size for such entities was assumed to be <35 kb; conversely, the minimal cellular DNA genome is ~200 kb. This large difference presents a daunting gap for the proposed evolution of contemporary DNA-RNP-based life from primordial RNP entities. Here, we describe a nidovirus from planarians, whose 41.1 kb genome is 23% larger than the largest known of RNA virus. The planarian secretory cell nidovirus has broken apparent constraints on the size of the genomic subregion that encodes core replication machinery, and has acquired genes not previously observed in RNA viruses. This virus challenges and advances our understanding of the limits to RNA genome size. author/funder. All rights reserved. No reuse allowed without permission.

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“…Thus, the combination of BEN domain and RNase T2 suggests that these BEN genes may play a role in a specific RNA processing with help of adaptor activity of the BEN domain. Indeed, the immunosuppression induced by CpBV-ORF301 expression was explained by its specific mRNA knockdown probably by specific degradation of antimicrobial peptides (Park and Kim, 2012), suggesting a specific inhibitory RNA processing against immune-associated mRNAs which may be recognized by the BEN domain. Other eight BEN genes do not have RNase T2 domain, but showed immunosuppressive activities.…”

Section: Discussionmentioning

confidence: 99%

“…CpBV ORF301 inhibits specific mRNA expression probably with nuclease activity of its RNase T 2 domain, which results in suppressing both cellular and humoral immune responses of host insects (Park and Kim, 2012). In addition to CpBV301, this study identifies another 10 CpBV genes containing BEN domain from a full sequence of episomal CpBV genome (Chen et al, 2011) and proposes a new BEN PDV family.…”

Section: Introductionmentioning

confidence: 96%