Hypovirus Papain-Like Protease p29 Functions in
            <i>trans</i>
            To Enhance Viral Double-Stranded RNA Accumulation and Vertical Transmission

Suzuki, Nobuhiro; Maruyama, K.; Moriyama, Miho; Nuss, Donald L.

doi:10.1128/jvi.77.21.11697-11707.2003

Cited by 76 publications

(98 citation statements)

References 47 publications

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“…When supplied transgenically, CHV1 p29 enhances in trans replication of homologous virus mutants lacking p29 (50) and heterologous viruses (16) in their natural host fungus, C. parasitica. Although it remains unclear how CHV1 p29 acts as a VSR, it has been suggested previously that its activity suppresses the transcription levels of host dcl-2 and agl-2 genes (26,27).…”

Section: Discussionmentioning

confidence: 99%

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A Novel Victorivirus from a Phytopathogenic Fungus, Rosellinia necatrix, Is Infectious as Particles and Targeted by RNA Silencing

Chiba

Lin

Kondō

et al. 2013

J Virol

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Japan bA novel victorivirus, termed Rosellinia necatrix victorivirus 1 (RnVV1), was isolated from a plant pathogenic ascomycete, white root rot fungus Rosellinia necatrix, coinfected with a partitivirus. The virus was molecularly and biologically characterized using the natural and experimental hosts (chestnut blight fungus, Cryphonectria parasitica). RnVV1 was shown to have typical molecular victorivirus attributes, including a monopartite double-stranded RNA genome with two open reading frames (ORFs) encoding capsid protein (CP) and RNA-dependent RNA polymerase (RdRp), a UAAUG pentamer presumed to facilitate the coupled termination/reinitiation for translation of the two ORFs, a spherical particle structure ϳ40 nm in diameter, and moderate levels of CP and RdRp sequence identity (34 to 58%) to those of members of the genus Victorivirus within the family Totiviridae. A reproducible transfection system with purified RnVV1 virions was developed for the two distinct fungal hosts. Transfection assay with purified RnVV1 virions combined with virus elimination by hyphal tipping showed that the effects of RnVV1 on the phenotype of the natural host were negligible. Interestingly, comparison of the RNA silencing-competent (standard strain EP155) and -defective (⌬dcl-2) strains of C. parasitica infected with RnVV1 showed that RNA silencing acted against the virus to repress its replication, which was restored by coinfection with hypovirus or transgenic expression of an RNA silencing suppressor, hypovirus p29. Phenotypic changes were observed in the ⌬dcl-2 strain but not in EP155. This is the first reported study on the host range expansion of a Totiviridae member that is targeted by RNA silencing.

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Section: Discussionmentioning

confidence: 99%

“…RNA samples were obtained from mycelia using the method of Chiba et al (17), and Northern blot analysis was conducted according to the method of Suzuki et al (50). After phenolchloroform extraction of fungal homogenate, total RNA was obtained by ethanol precipitation, whereas ssRNA was obtained by lithium chloride precipitation.…”

Section: Methodsmentioning

confidence: 99%

A Novel Victorivirus from a Phytopathogenic Fungus, Rosellinia necatrix, Is Infectious as Particles and Targeted by RNA Silencing

Chiba

Lin

Kondō

et al. 2013

J Virol

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“…In some fungi, the presence of dsRNA is related to several phenotypic alterations (Day et al, 1977;Zhou & Boland, 1997, 1999Liu et al, 2003a;Suzuki et al, 2003;Kwon et al, 2009). Viral infection reduces the levels of α and β subunits of protein G, changing the transduction signal of this protein in the host (Dawe et al, 2004).…”

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confidence: 99%

Detection of isometric, dsRNA-containing viral particles in Colletotrichum gloeosporioides isolated from cashew tree

Figueirêdo

Giancoli

et al. 2012

Trop. plant pathol.

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Fungi are disease-causing agents in plants and affect crops of economic importance. One control method is to induce resistance in the host by using biological control with hypovirulent phytopathogenic fungi. Here, we report the detection of a mycovirus in a strain of Colletotrichum gloeosporioides causing anthracnose of cashew tree. The strain C. gloeosporioides URM 4903 was isolated from a cashew tree (Anacardium occidentale) in Igarassu, PE, Brazil. After nucleic acid extraction and electrophoresis, the band corresponding to a possible double-stranded RNA (dsRNA) was purified by cellulose column chromatography. Nine extrachromosomal bands were obtained. Enzymatic digestion with DNAse I and Nuclease S1 had no effect on these bands, indicating their dsRNA nature. Transmission electron microscopic examination of extracts from this strain showed the presence of isometric particles (30-35 nm in diameter). These data strongly suggest the infection of this C. gloeosporioides strain by a dsRNA mycovirus. Once the hypovirulence of this strain is confirmed, the strain may be used for the biological control of cashew anthracnose. Key words: Anacardium occidentale, anthracnose, biological control, hypovirulence, mycovirus, phytopathogenic fungi.Fungi are the most important disease-causing agents in plants with serious economic impact. Chemical methods to control phytopathogenic fungi can affect human health and have environmental consequences. In an attempt to minimize dependence on chemical methods, alternative means of pathogen control have been investigated (Yu et al., 2010). One alternative is to use hypovirulent phytopathogenic fungal strains that can biologically control phytopathogenic fungi of the same or related species. Fungal hypovirulence is usually caused by mycoviral infection. Hypovirulent fungi cause milder infection and may induce hypovirulence in other pathogenic strains via viral transfer (Pearson et al., 2009).All currently known mycoviruses have isometric, double-stranded RNA (dsRNA)-containing particles, and are classified into three families: Chrysoviridae, Endornaviridae, Partitiviridae and Totiviridae. Particle size ranges from 25 to 50 nm in diameter, except for endornaviruses which do not produce virions (Chu et al., 2002;Ghabrial & Suzuki, 2009).In this communication, we report the presence of isometric dsRNA viral particles in a strain of Colletotrichum gloeosporioides (Penz.) Sacc., the causal agent of anthracnose in cashew tree.Colletotrichum gloeosporioides URM 4903 was isolated from anthracnose lesions on a cashew tree (Anacardium occidentale L.) in the town of Igarassu, Pernambuco, Brazil (7°50'3.74"S and 34°54'22.87"O), and deposited in the mycology collection (URM) at Federal University of Pernambuco, Recife, PE. This strain was chosen after preliminary tests revealed poor pathogenicity in detached cashew leaves and the presence of extrachromosomal bands in agarose gel electrophoresis (unpublished data).PDA (20% potato extract, 2% dextrose, 1.5% agar) and PD (20% potato extract,...

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“…Since CHV1 affects development without affecting vegetative growth of the fungus, it is likely that the effect of the virus on fungal development is specific rather than a result of general debilitation, making this an excellent model system. There has been progress in the identification of virus-encoded hypovirulence symptom determinants (57,58), the identification of specific host genes and proteins affected by CHV1 (29,41) and, with this report, an understanding of the nature of the vesicles used by the virus for replication. Current evolutionary evidence indicates a common ancestry of the chestnut blight hypovirulence-associated dsRNA with the potyviruses (30), a group of positive-strand RNA plant viruses.…”

Section: Vol 80 2006 Chv1 Cofractionates With Host Tgn Membranes 6593mentioning

confidence: 99%

“…Functions assigned to p29 include autoproteolysis and suppression of host lacasse expression, pigment production, and asexual sporulation (10). p29 also enhances viral dsRNA accumulation and vertical virus transmission through asexual spores (58).…”

Section: Vol 80 2006 Chv1 Cofractionates With Host Tgn Membranes 6593mentioning

confidence: 99%

Mycovirus Cryphonectria Hypovirus 1 Elements Cofractionate with trans -Golgi Network Membranes of the Fungal Host Cryphonectria parasitica

Jacob-Wilk

Turina

Alfen

2006

J Virol

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The mycovirus cryphonectria hypovirus 1 (CHV1) causes proliferation of vesicles in its host, Cryphonectria parasitica, the causal agent of chestnut blight. These vesicles have previously been shown to contain both CHV1 genomic double-stranded RNA (dsRNA) and RNA polymerase activity. To determine the cellular origins of these virus-induced membrane structures, we compared the fractionation of several cellular and viral markers. Results showed that viral dsRNA, helicase, polymerase, and protease p29 copurify with C. parasitica trans-Golgi network (TGN) markers, suggesting that the virus utilizes the fungal TGN for replication. We also show that the CHV1 protease p29 associates with vesicle membranes and is resistant to treatments that would release peripheral membrane proteins. Thus, p29 behaves as an integral membrane protein of the vesicular fraction derived from the fungal TGN. Protease p29 was also found to be fully susceptible to proteolytic digestion in the absence of detergent and, thus, is wholly or predominantly on the cytoplasmic face of the vesicles. Fractionation analysis of p29 deletion variants showed that sequences in the C terminal of p29 mediate membrane association. In particular, the C-terminal portion of the protein (Met-135-Gly-248) is sufficient for membrane association and is enough to direct p29 to the TGN vesicles in the absence of other viral elements.Cryphonectria parasitica is the filamentous ascomycete that causes chestnut blight, a disease that resulted in the nearly complete demise of the American chestnut tree (25). Mycovirus cryphonectria hypovirus 1 (CHV1) infection of C. parasitica reduces virulence of the fungus and has been exploited for the biocontrol of chestnut blight in Europe (24). CHV1 is a member of the virus family Hypoviridae, distinguished by the ability to attenuate virulence and alter developmental processes upon infection of the fungal host. Specific symptoms of virus infection of the fungus grown in culture include reduced pigment production, suppressed asexual sporulation, loss of female fertility, and modified expression of specific host genes (27,29,39,40).CHV1 has a double-stranded RNA (dsRNA) genome and, like other fungal virus dsRNAs, that of CHV1 is not infectious but can be transmitted horizontally by fungal anastomosis (38) and vertically through asexual, but not sexual, spores. Although hypovirus RNA is found in hyphal extracts as dsRNA, the structural characteristics of the dsRNA are reminiscent of a replicative intermediate or replicative form of a singlestranded RNA (ssRNA) virus (53). In CHV1, the 12.7-kb positive, coding strand is polyadenylated and contains two contiguous open reading frames (ORFs A and B) that encode polyproteins that undergo proteolytic processing (6, 7, 54). Domains in both ORF A and ORF B share sequence homology with ssRNA plant potyviruses (30) and the polyadenylated strand is infectious (3), which is consistent with the ssRNA viral replication strategy (11,44). CHV1 infection of C. parasitica causes proliferation of vesicles ...

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Hypovirus Papain-Like Protease p29 Functions in trans To Enhance Viral Double-Stranded RNA Accumulation and Vertical Transmission

Cited by 76 publications

References 47 publications

A Novel Victorivirus from a Phytopathogenic Fungus, Rosellinia necatrix, Is Infectious as Particles and Targeted by RNA Silencing

A Novel Victorivirus from a Phytopathogenic Fungus, Rosellinia necatrix, Is Infectious as Particles and Targeted by RNA Silencing

Detection of isometric, dsRNA-containing viral particles in Colletotrichum gloeosporioides isolated from cashew tree

Mycovirus Cryphonectria Hypovirus 1 Elements Cofractionate with trans -Golgi Network Membranes of the Fungal Host Cryphonectria parasitica

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