The Experts below are selected from a list of 177 Experts worldwide ranked by ideXlab platform
Bradley I. Hillman - One of the best experts on this subject based on the ideXlab platform.
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Investigation of Host Range of and Host Defense against a Mitochondrially Replicating Mitovirus
Journal of Virology, 2019Co-Authors: Sabitree Shahi, Bradley I. Hillman, Ana Eusebio-cope, Hideki Kondo, Nobuhiro SuzukiAbstract:Mitoviruses (genus Mitovirus, family Narnaviridae) are mitochondrially replicating viruses that have the simplest positive-sense RNA genomes of 2.2 to 4.4 kb with a single open reading frame (ORF) encoding an RNA-dependent RNA polymerase. Cryphonectria parasitica mitovirus 1 (CpMV1) from U.S. strain NB631 of the chestnut blight fungus, Cryphonectria parasitica, was the first virus identified as a mitochondrially replicating virus. Despite subsequent discovery of many other mitoviruses from diverse fungi, no great advances in understanding mitovirus biology have emerged, partly because of the lack of inoculation methods. Here we developed a protoplast fusion-based protocol for horizontal transmission of CpMV1 that entailed fusion of recipient and donor protoplasts, hyphal anastomosis, and single-conidium isolation. This method allowed expansion of the host range to many other C. parasitica strains. Species within and outside the family Cryphonectriaceae, Cryphonectria radicalis and Valsa ceratosperma, also supported the replication of CpMV1 at a level comparable to that in the natural host. No stable maintenance of CpMV1 was observed in Helminthosporium victoriae. PCR-based haplotyping of virus-infected fungal strains confirmed the recipient mitochondrial genetic background. Phenotypic comparison between CpMV1-free and -infected isogenic strains revealed no overt effects of the virus. Taking advantage of the infectivity to the standard strain C. parasitica EP155, accumulation levels were compared among antiviral RNA silencing-proficient and -deficient strains in the EP155 background. Comparable accumulation levels were observed among these strains, suggesting the avoidance of antiviral RNA silencing by CpMV1, which is consistent with its mitochondrial replication. Collectively, the results of study provide a foundation to further explore the biology of mitoviruses. IMPORTANCE Capsidless mitoviruses, which are ubiquitously detected in filamentous fungi, have the simplest RNA genomes of 2.2 to 4.4 kb, encoding only RNA-dependent RNA polymerase. Despite their simple genomes, detailed biological characterization of mitoviruses has been hampered by their mitochondrial location within the cell, posing challenges to their experimental introduction and study. Here we developed a protoplast fusion-based protocol for horizontal transfer of the prototype mitovirus, Cryphonectria parasitica mitovirus 1 (CpMV1), which was isolated from strain NB631 of the chestnut blight fungus (Cryphonectria parasitica), a model filamentous fungus for studying virus-host interactions. The host range of CpMV1 has been expanded to many different strains of C. parasitica and different fungal species within and outside the Cryphonectriaceae. Comparison of CpMV1 accumulation among various RNA silencing-deficient and -competent strains showed clearly that the virus was unaffected by RNA silencing. This study provides a solid foundation for further exploration of mitovirus-host interactions.
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the family Narnaviridae simplest of rna viruses
Advances in Virus Research, 2013Co-Authors: Bradley I. HillmanAbstract:Abstract Members of the virus family Narnaviridae contain the simplest genomes of any RNA virus, ranging from 2.3 to 3.6 kb and encoding only a single polypeptide that has an RNA-dependent RNA polymerase domain. The family is subdivided into two genera based on subcellular location: members of the genus Narnavirus have been found in the yeast Saccharomyces cerevisiae and in the oomycete Phytophthora infestans and are confined to the cytosol, while members of the genus Mitovirus have been found only in filamentous fungi and are found in mitochondria. None identified thus far encodes a capsid protein; like several other RNA viruses of lower eukaryotes, their genomes are confined within lipid vesicles. As more family members are discovered, their importance as genetic elements is becoming evident. The unique association of the genus Mitovirus with mitochondria renders them potentially valuable tools to study biology of lower eukaryotes.
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Chapter Twelve - Phytophthora Viruses
Advances in Virus Research, 2013Co-Authors: Bradley I. HillmanAbstract:Phytophthora sp. is a genus in the oomycetes, which are similar to filamentous fungi in morphology and habitat, but phylogenetically more closely related to brown algae and diatoms and fall in the kingdom Stramenopila. In the past few years, several viruses have been characterized in Phytophthora species, including four viruses from Phytophthora infestans, the late blight pathogen, and an endornavirus from an unnamed Phytophthora species from Douglas fir. Studies on Phytophthora viruses have revealed several interesting systems. Phytophthora infestans RNA virus 1 (PiRV-1) and PiRV-2 are likely the first members of two new virus families; studies on PiRV-3 support the establishment of a new virus genus that is not affiliated with established virus families; PiRV-4 is a member of Narnaviridae, most likely in the genus Narnavirus; and Phytophthora endornavirus 1 (PEV1) was the first nonplant endornavirus at the time of reporting. Viral capsids have not been found in any of the above-mentioned viruses. PiRV-1 demonstrated a unique genome organization that requires further examination, and PiRV-2 may have played a role in late blight resurgence in 1980s–1990s.
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A new virus from the plant pathogenic oomycete Phytophthora infestans with an 8 kb dsRNA genome: The sixth member of a proposed new virus genus
Virology, 2012Co-Authors: Jason F. Krychiw, Kevin Myers, Bradley I. HillmanAbstract:A virus designated Phytophthora infestans RNA virus 3 (PiRV-3) was characterized from an isolate of P. infestans that was co-infected with a second previously described virus, PiRV-4, a member of the virus family Narnaviridae (Cai et al., 2012). The genome of PiRV-3 is 8112 nt and one strand, designated the positive strand, has two deduced overlapping open reading frames linked by a potential frameshift sequence. The first open reading frame (ORF1) is predicted to encode a protein of unknown function, and ORF2 is predicted to encode an RNA-dependent RNA polymerase (RdRp) most closely related to six unclassified dsRNA viruses of filamentous fungi. The genome organizations of five of the related viruses are similar to PiRV-3, indicating taxonomic linkage among those viruses. We suggest that PiRV-3 and related viruses should be collected into a new virus taxon.
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A member of the virus family Narnaviridae from the plant pathogenic oomycete Phytophthora infestans
Archives of Virology, 2012Co-Authors: Kevin Myers, Bradley I. HillmanAbstract:A virus that has properties consistent with inclusion in the virus family Narnaviridae was described in Phytophthora infestans , the oomycete that caused the Irish potato famine. The genome of phytophthora infestans RNA virus 4 (PiRV-4) is 2,984 nt with short complementary terminal sequences and a single open reading frame predicted to encode an RNA-dependent RNA polymerase (RdRp) most closely related to saccharomyces cerevisiae narnavirus 20S (ScNV-20S) and ScNV-23S, the members of the genus Narnavirus , family Narnaviridae . This report constitutes the first description of a member of the family Narnaviridae from a host taxon outside of the kingdom Fungi.
Delano James - One of the best experts on this subject based on the ideXlab platform.
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Two novel mitoviruses from a Canadian isolate of the Dutch elm pathogen Ophiostoma novo-ulmi (93–1224)
Virology Journal, 2013Co-Authors: William E Hintz, Joyce S Carneiro, Irina Kassatenko, Aniko Varga, Delano JamesAbstract:Background Ophiostoma novo-ulmi is the causative agent of Dutch elm disease (DED). It is an ascomycetous filamentous fungus that ranks as the third most devastating fungal pathogen in Canada. The disease front has spread eastward and westward from the epicentre in Ontario and Quebec and is threatening elm populations across the country. Numerous mitigation strategies have been tried to eradicate this pathogen, but success has thus far been limited. An alternative approach might utilize double-stranded RNA (dsRNA) mycoviruses which have been reported to induce hypovirulence in other fungi. Methods Using a modified single primer amplification technique (SPAT) in combination with chromosomal walking, we have determined the genome sequence of two RdRp encoding dsRNA viruses from an O. novo-ulmi isolate (93–1224) collected from the disease front in Winnipeg. Results We propose that these viruses, which we have named OnuMV1c and OnuMV7 based on sequence similarity to other Ophiostoma mitoviruses, are two new members of the genus Mitovirus in the family Narnaviridae. Conclusions The discovery of such dsRNA elements raises the potential for engineering these viruses to include other genetic elements, such as anti-sense or interfering RNAs, to create novel and highly specific biological controls. Naïve fungal hosts could be infected with both the engineered molecule and a helper mitovirus encoding an RdRp which would provide replication capacity for both molecules.
Julio J. Diez - One of the best experts on this subject based on the ideXlab platform.
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Three mitovirus strains infecting a single isolate of Fusarium circinatum are the first putative members of the family Narnaviridae detected in a fungus of the genus Fusarium
Archives of Virology, 2014Co-Authors: Pablo Martínez-Álvarez, Eeva J Vainio, Jarkko Hantula, Leticia Botella, Julio J. DiezAbstract:Fusarium circinatum Nirenberg & O’Donnell (teleomorph = Gibberella circinata ) is the causal agent of pitch canker disease of pines. Since 2004 it has been present in Europe, particularly in northern Spain, affecting P. radiata and P. pinaster in plantations and nurseries. The disease has now also spread to other European countries, including France, Italy and Portugal. In this report, we describe three novel members of the genus Mitovirus from a Spanish isolate of F. circinatum : Fusarium circinatum mitovirus 1 (FcMV1), FcMV2-1 and FcMV2-2. Using a mitochondrial translation table, the complete 2419-bp genome of FcMV1 encodes an RNA-dependent RNA polymerase of 731 amino acids (GC-content ca 30 %). The partial genomes of FcMV2-1 and FcMV2-2 (2193 and 1973 bp, respectively) share ca 48 % RdRp sequence similarity at the aa level and might be regarded as conspecific, while FcMV1 is clearly distinct, showing 32-35 % polymerase similarity to the other strains. However, FcMV1 shared 46 % protein-level similarity with Thielaviopsis basicola mitovirus. This is the first study to report viruses in F. circinatum , as well as the first time that mitovirus genome sequences are described from Fusarium spp.
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Presence of Viral dsRNA molecules in the Spanish population of Gremmeniella abietina
Journal of Agricultural Extension and Rural Development, 2012Co-Authors: Leticia Botella, Jarkko Hantula, Tero Tuomivirta, Julio J. DiezAbstract:Gremmeniella abietina var. abietina has commonly been pointed out as a species complex, which includes different races and biotypes. Among them, the Spanish population seems to be a unique population derived from type A. Furthermore, G. abietina is known to harbour infections and co-infections of putative mycoviruses belonging to different families. In particular, G. abietinatype A harbours putative members of families Totiviridae and Partitiviridae but also Narnaviridae, with members of genus Mitovirus. In case of G. abietina type B, a novel putative virus with endornavirus affinities has also been identified. Different types of G. abietina seem to host a divergent virus community. So, ninety-one isolates of the Spanish G. abietina were analyzed to check out the presence of viral dsRNA molecules. Thus, the 89% of Spanish isolates presented at least one dsRNA molecule, which is a significant frequency. Overall, eight dsRNA banding patterns were detected, suggesting the occurrence of putative members of different virus genera as Partitivirus, Mitovirus and Totivirus. This is the first approach to the study of fungal mycoviruses in the Spanish population of G. abietina. Key words: Gremmeniella, mycovirus, host, dsRNA, taxonomy.
Hiromitsu Moriyama - One of the best experts on this subject based on the ideXlab platform.
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Genome sequence of a novel mitovirus identified in the phytopathogenic fungus Alternaria arborescens
Archives of Virology, 2016Co-Authors: Ken Komatsu, Yukie Katayama, Tsutomu Omatsu, Tetsuya Mizutani, Toshiyuki Fukuhara, Motoichiro Kodama, Tsutomu Arie, Tohru Teraoka, Hiromitsu MoriyamaAbstract:The phytopathogenic fungus Alternaria spp. contains a variety of double-stranded RNA (dsRNA) elements of different sizes. Detailed analysis of next-generation sequencing data obtained using dsRNA purified from Alternaria arborescens , from which we had previously found Alternaria arborescens victorivirus 1, revealed the presence of another mycoviral-like dsRNA of approximately 2.5 kbp in length. When using the fungal mitochondrial genetic code, this dsRNA has a single open reading frame that potentially encodes an RNA-dependent RNA polymerase (RdRp) with significant to sequence similarity to those of viruses of the genus Mitovirus . Moreover, both the 5’- and 3’-untranslated regions have the potential to fold into stable stem-loop structures, which is characteristic of mitoviruses. Pairwise comparisons and phylogenetic analysis of the deduced amino acid sequences of RdRp indicated that the virus we identified in A. arborescens is a distinct member of the genus Mitovirus in the family Narnaviridae , designated as “Alternaria arborescens mitovirus 1” (AaMV1).
William E Hintz - One of the best experts on this subject based on the ideXlab platform.
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Two novel mitoviruses from a Canadian isolate of the Dutch elm pathogen Ophiostoma novo-ulmi (93–1224)
Virology Journal, 2013Co-Authors: William E Hintz, Joyce S Carneiro, Irina Kassatenko, Aniko Varga, Delano JamesAbstract:Background Ophiostoma novo-ulmi is the causative agent of Dutch elm disease (DED). It is an ascomycetous filamentous fungus that ranks as the third most devastating fungal pathogen in Canada. The disease front has spread eastward and westward from the epicentre in Ontario and Quebec and is threatening elm populations across the country. Numerous mitigation strategies have been tried to eradicate this pathogen, but success has thus far been limited. An alternative approach might utilize double-stranded RNA (dsRNA) mycoviruses which have been reported to induce hypovirulence in other fungi. Methods Using a modified single primer amplification technique (SPAT) in combination with chromosomal walking, we have determined the genome sequence of two RdRp encoding dsRNA viruses from an O. novo-ulmi isolate (93–1224) collected from the disease front in Winnipeg. Results We propose that these viruses, which we have named OnuMV1c and OnuMV7 based on sequence similarity to other Ophiostoma mitoviruses, are two new members of the genus Mitovirus in the family Narnaviridae. Conclusions The discovery of such dsRNA elements raises the potential for engineering these viruses to include other genetic elements, such as anti-sense or interfering RNAs, to create novel and highly specific biological controls. Naïve fungal hosts could be infected with both the engineered molecule and a helper mitovirus encoding an RdRp which would provide replication capacity for both molecules.
