scholarly journals Prevalence and Diversity of Viruses in the Entomopathogenic Fungus Beauveria bassiana

2012 ◽  
Vol 78 (24) ◽  
pp. 8523-8530 ◽  
Author(s):  
Noemí Herrero ◽  
Encarna Dueñas ◽  
Enrique Quesada-Moraga ◽  
Iñigo Zabalgogeazcoa
Keyword(s):  
Beauveria Bassiana ◽  
Entomopathogenic Fungi ◽  
Viral Infections ◽  
Biological Control Agent ◽  
Rna Virus ◽  
Plant Viruses ◽  
Hybridization Experiment ◽  
Virus Species ◽  
Content Type ◽  
Virus Diversity

ABSTRACTViruses have been discovered in numerous fungal species, but unlike most known animal or plant viruses, they are rarely associated with deleterious effects on their hosts. The knowledge about viruses among entomopathogenic fungi is very limited, although their existence is suspected because of the presence of virus-like double-stranded RNA (dsRNA) in isolates of several species.Beauveria bassianais one of the most-studied species of entomopathogenic fungi; it has a cosmopolitan distribution and is used as a biological control agent against invertebrates in agriculture. We analyzed a collection of 73 isolates obtained at different locations and from different habitats in Spain and Portugal, searching for dsRNA elements indicative of viral infections. The results revealed that the prevalence of viral infections is high; 54.8% of the isolates contained dsRNA elements with viral characteristics. The dsRNA electropherotypes of infected isolates indicated that virus diversity was high in the collection analyzed and that mixed virus infections occurred in fungal isolates. However, a hybridization experiment indicated that dsRNA bands that are similar in size do not always have similar sequences. Particular virus species or dsRNA profiles were not associated with locations or types of habitats, probably because of the ubiquity and efficient dispersion of this fungus as an airborne species. The sequence of one of the most common dsRNA elements corresponded to the 5.2-kbp genome of a previously undescribed member of theTotiviridaefamily, termedB. bassianaRNA virus 1 (BbRV1).

scholarly journals High-Resolution Metatranscriptomics Reveals the Ecological Dynamics of Mosquito-Associated RNA Viruses in Western Australia

2017 ◽  
Vol 91 (17) ◽  
Author(s):  
Mang Shi ◽  
Peter Neville ◽  
Jay Nicholson ◽  
John-Sebastian Eden ◽  
Allison Imrie ◽  
...  
Keyword(s):  
Western Australia ◽  
Rna Viruses ◽  
Rna Virus ◽  
Geographic Location ◽  
Striking Difference ◽  
Sampling Location ◽  
Virus Species ◽  
Diverse Range ◽  
Content Type ◽  
Virus Diversity

ABSTRACT Mosquitoes harbor a high diversity of RNA viruses, including many that impact human health. Despite a growing effort to describe the extent and nature of the mosquito virome, little is known about how these viruses persist, spread, and interact with both their hosts and other microbes. To address this issue we performed a metatranscriptomics analysis of 12 Western Australian mosquito populations structured by species and geographic location. Our results identified the complete genomes of 24 species of RNA viruses from a diverse range of viral families and orders, among which 19 are newly described. Comparisons of viromes revealed a striking difference between the two mosquito genera, with viromes of mosquitoes of the Aedes genus exhibiting substantially less diversity and lower abundances than those of mosquitoes of the Culex genus, within which the viral abundance reached 16.87% of the total non-rRNA. In addition, there was little overlap in viral diversity between the two genera, although the viromes were very similar among the three Culex species studied, suggesting that the host taxon plays a major role in structuring virus diversity. In contrast, we found no evidence that geographic location played a major role in shaping RNA virus diversity, and several viruses discovered here exhibited high similarity (95 to 98% nucleotide identity) to those from Indonesia and China. Finally, using abundance-level and phylogenetic relationships, we were able to distinguish potential mosquito viruses from those present in coinfecting bacteria, fungi, and protists. In sum, our metatranscriptomics approach provides important insights into the ecology of mosquito RNA viruses. IMPORTANCE Studies of virus ecology have generally focused on individual viral species. However, recent advances in bulk RNA sequencing make it possible to utilize metatranscriptomic approaches to reveal both complete virus diversity and the relative abundance of these viruses. We used such a metatranscriptomic approach to determine key aspects of the ecology of mosquito viruses in Western Australia. Our results show that RNA viruses are some of the most important components of the mosquito transcriptome, and we identified 19 new virus species from a diverse set of virus families. A key result was that host genetic background plays a more important role in shaping virus diversity than sampling location, with Culex species harboring more viruses at higher abundance than those from Aedes mosquitoes.

scholarly journals Diversity of Active Viral Infections within the Sphagnum Microbiome

2018 ◽  
Vol 84 (23) ◽  
Author(s):  
Joshua M. A. Stough ◽  
Max Kolton ◽  
Joel E. Kostka ◽  
David J. Weston ◽  
Dale A. Pelletier ◽  
...  
Keyword(s):  
Capsid Protein ◽  
Viral Infections ◽  
Model Systems ◽  
Microbial Consortia ◽  
Soil Conditions ◽  
Marker Genes ◽  
Ecological Value ◽  
Metabolic Potential ◽  
Content Type ◽  
Virus Diversity

ABSTRACT Sphagnum-dominated peatlands play an important role in global carbon storage and represent significant sources of economic and ecological value. While recent efforts to describe microbial diversity and metabolic potential of the Sphagnum microbiome have demonstrated the importance of its microbial community, little is known about the viral constituents. We used metatranscriptomics to describe the diversity and activity of viruses infecting microbes within the Sphagnum peat bog. The vegetative portions of six Sphagnum plants were obtained from a peatland in northern Minnesota, and the total RNA was extracted and sequenced. Metatranscriptomes were assembled and contigs were screened for the presence of conserved virus marker genes. Using bacteriophage capsid protein gp23 as a marker for phage diversity, we identified 33 contigs representing undocumented phages that were active in the community at the time of sampling. Similarly, RNA-dependent RNA polymerase and the nucleocytoplasmic large DNA virus (NCLDV) major capsid protein were used as markers for single-stranded RNA (ssRNA) viruses and NCLDV, respectively. In total, 114 contigs were identified as originating from undescribed ssRNA viruses, 22 of which represent nearly complete genomes. An additional 64 contigs were identified as being from NCLDVs. Finally, 7 contigs were identified as putative virophage or polinton-like viruses. We developed co-occurrence networks with these markers in relation to the expression of potential-host housekeeping gene rpb1 to predict virus-host relationships, identifying 13 groups. Together, our approach offers new tools for the identification of virus diversity and interactions in understudied clades and suggests that viruses may play a considerable role in the ecology of the Sphagnum microbiome. IMPORTANCE Sphagnum-dominated peatlands play an important role in maintaining atmospheric carbon dioxide levels by modifying conditions in the surrounding soil to favor the growth of Sphagnum over that of other plant species. This lowers the rate of decomposition and facilitates the accumulation of fixed carbon in the form of partially decomposed biomass. The unique environment produced by Sphagnum enriches for the growth of a diverse microbial consortia that benefit from and support the moss's growth, while also maintaining the hostile soil conditions. While a growing body of research has begun to characterize the microbial groups that colonize Sphagnum, little is currently known about the ecological factors that constrain community structure and define ecosystem function. Top-down population control by viruses is almost completely undescribed. This study provides insight into the significant viral influence on the Sphagnum microbiome and identifies new potential model systems to study virus-host interactions in the peatland ecosystem.

scholarly journals Circulative Nonpropagative Aphid Transmission of Nanoviruses: an Oversimplified View

2015 ◽  
Vol 89 (19) ◽  
pp. 9719-9726 ◽  
Author(s):  
Anne Sicard ◽  
Jean-Louis Zeddam ◽  
Michel Yvon ◽  
Yannis Michalakis ◽  
Serafin Gutiérrez ◽  
...  
Keyword(s):  
Salivary Glands ◽  
Faba Bean ◽  
Plant Viruses ◽  
The Body ◽  
Virus Species ◽  
Content Type ◽  
Aphid Vector ◽  
Arthropod Vectors ◽  
The Family ◽  
Aphid Vectors

ABSTRACTPlant virus species of the familyNanoviridaehave segmented genomes with the highest known number of segments encapsidated individually. They thus likely represent the most extreme case of the so-called multipartite, or multicomponent, viruses. All species of the family are believed to be transmitted in a circulative nonpropagative manner by aphid vectors, meaning that the virus simply crosses cellular barriers within the aphid body, from the gut to the salivary glands, without replicating or even expressing any of its genes. However, this assumption is largely based on analogy with the transmission of other plant viruses, such as geminiviruses or luteoviruses, and the details of the molecular and cellular interactions between aphids and nanoviruses are poorly investigated. When comparing the relative frequencies of the eight genome segments in populations of the speciesFaba bean necrotic stunt virus(FBNSV) (genusNanovirus) within host plants and within aphid vectors fed on these plants, we unexpectedly found evidence of reproducible changes in the frequencies of some specific segments. We further show that these changes occur within the gut during early stages of the virus cycle in the aphid and not later, when the virus is translocated into the salivary glands. This peculiar observation, which was similarly confirmed in three aphid vector species,Acyrthosiphon pisum,Aphis craccivora, andMyzus persicae, calls for revisiting of the mechanisms of nanovirus transmission. It reveals an unexpected intimate interaction that may not fit the canonical circulative nonpropagative transmission.IMPORTANCEA specific mode of interaction between viruses and arthropod vectors has been extensively described in plant viruses in the three familiesLuteoviridae,Geminiviridae, andNanoviridae, but never in arboviruses of animals. This so-called circulative nonpropagative transmission contrasts with the classical biological transmission of animal arboviruses in that the corresponding viruses are thought to cross the vector cellular barriers, from the gut lumen to the hemolymph and to the salivary glands, without expressing any of their genes and without replicating. By monitoring the genetic composition of viral populations during the life cycle ofFaba bean necrotic stunt virus(FBNSV) (genusNanovirus), we demonstrate reproducible genetic changes during the transit of the virus within the body of the aphid vector. These changes do not fit the view that viruses simply traverse the bodies of their arthropod vectors and suggest more intimate interactions, calling into question the current understanding of circulative nonpropagative transmission.

scholarly journals Laboratory and Greenhouse Evaluation of a Granular Formulation of Beauveria bassiana for Control of Western Flower Thrips, Frankliniella occidentalis

Insects ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 58 ◽  
Author(s):  
Xingrui Zhang ◽  
Zhongren Lei ◽  
Stuart Reitz ◽  
Shengyong Wu ◽  
Yulin Gao
Keyword(s):  
Soil Moisture ◽  
Beauveria Bassiana ◽  
Entomopathogenic Fungi ◽  
Frankliniella Occidentalis ◽  
Western Flower Thrips ◽  
Plant Viruses ◽  
Infection Process ◽  
The Body ◽  
Plant Production ◽  
Flower Thrips

Western flower thrips (WFT) is one of the most important pests of horticultural crops worldwide because it can damage many different crops and transmit various plant viruses. Given these significant impacts on plant production, novel methodologies are required to maximize regulation of WFT to minimize crop losses. One particular approach is to develop control strategies for the non-feeding, soil-dwelling stages of WFT. Control of these stages could be enhanced through the use of granules impregnated with entomopathogenic fungi mixed in the soil. The use of soil-applied fungi contrasts with existing approaches in which entomopathogenic fungi are formulated as oil-based suspensions or water-based wettable powders for foliar applications against the feeding stages of WFT. To examine the efficacy of this approach, we evaluated the effects of a granular formulation of Beauveria bassiana on the soil-dwelling, pupal phases of Frankliniella occidentalis in laboratory bioassays and greenhouse experiments. Based on micromorphological observations of fungal conidia during the infection process after treatment of WFT with a B. bassiana suspension, fungal conidia complete the process of surface attachment, germination, and penetration of the body wall of the WFT pupa and enter the host within 60 h of treatment. Given these results, we undertook a controlled greenhouse experiment and applied B. bassiana granules to soil used to cultivate eggplants. Populations of F. occidentalis on eggplants grown in treated soil were 70% lower than those on plants grown in the untreated soil after 8 weeks. Furthermore, when measuring the survival and growth of B. bassiana on granules under different soil moisture conditions, survival was greatest when the soil moisture content was kept at 20%. These results indicate that the application of B. bassiana-impregnated granules could prove to be an effective biological control strategy for use against F. occidentalis under greenhouse conditions.

scholarly journals Spatiotemporal dynamics of RNA virus diversity in a phyllosphere microbial community

2019 ◽  
Author(s):  
Lisa M. Bono ◽  
Richard J. Orton ◽  
Elena L. Peredo ◽  
Hilary G. Morrison ◽  
Mark Sistrom ◽  
...  
Keyword(s):  
White Clover ◽  
Rna Virus ◽  
Alpha Diversity ◽  
Spatiotemporal Dynamics ◽  
Virus Species ◽  
Terrestrial Plants ◽  
High Coverage ◽  
Virus Family ◽  
Virus Diversity ◽  
Over Time

AbstractAlthough metagenomics reveals that natural virus communities harbor vast genetic diversity, the spatiotemporal dynamics of viral diversity in the wild are seldom tested, especially across small geographic scales. This problem is usefully examined in the above-ground phyllosphere, because terrestrial plants are frequently infected by taxonomically-diverse RNA viruses, whose elevated mutation rates generate abundant allele diversity. Here, we studied the problem by comparative analysis of RNA virus samples over time from three spatially-separated patches of a common perennial legume, white clover (Trifolium repens L.), growing in a grassy lawn in Woods Hole Village (Falmouth, MA, USA). We predicted that clover samples would show similarly high levels of virus species (alpha) diversity across space, but differing among-patch diversity of non-dominant virus taxa over time (4 samples spanning 6 weeks). Results showed that recognizable alpha diversity in clover patches was consistently dominated by RNA virus family Alphaflexiviridae across space, but that all patches showed inconsistent spatiotemporal presence of a diversity of minority virus families. Also, we observed that white clover mosaic virus (WClMV) dominated all patches across space and time. The high coverage of WClMV fostered an haplotype analysis, which revealed that two strains of the virus consistently infected clover plants during the 6-week period.

scholarly journals Revealing RNA virus diversity and evolution in unicellular algae transcriptomes

2021 ◽  
Author(s):  
Justine Charon ◽  
Shauna Murray ◽  
Edward C Holmes
Keyword(s):  
Rna Viruses ◽  
Rna Virus ◽  
Sequence Similarity ◽  
Sequence Divergence ◽  
Virus Species ◽  
Sequencing Project ◽  
Virus Diversity ◽  
Microbial Eukaryotes ◽  
Unicellular Algae ◽  
Positive Sense

Remarkably little is known about the diversity and evolution of RNA viruses in unicellular eukaryotes. We screened a total of 570 transcriptomes from the Marine Microbial Eukaryote Transcriptome Sequencing Project (MMETSP) project that encompasses a wide diversity of microbial eukaryotes, including most major photosynthetic lineages (i.e. the microalgae). From this, we identified 30 new and divergent RNA virus species, occupying a range of phylogenetic positions within the overall diversity of RNA viruses. Approximately one-third of the newly described viruses comprised single-stranded positive-sense RNA viruses from the order Lenarviricota associated with fungi, plants and protists, while another third were related to the order Ghabrivirales, including members of the protist and fungi-associated Totiviridae. Other viral species showed sequence similarity to positive-sense RNA viruses from the algae-associated Marnaviridae, the double-stranded RNA Partitiviridae, as well as a single negative-sense RNA virus related to the Qinviridae. Importantly, we were able to identify divergent RNA viruses from distant host taxa, revealing the ancestry of these viral families and greatly extending our knowledge of the RNA viromes of microalgal cultures. Both the limited number of viruses detected per sample and the low sequence identity to known RNA viruses imply that additional microalgal viruses exist that could not be detected at the current sequencing depth or were too divergent to be identified using sequence similarity. Together, these results highlight the need for further investigation of algal-associated RNA viruses as well as the development of new tools to identify RNA viruses that exhibit very high levels of sequence divergence.

scholarly journals Conserved Motifs in a Tombusvirus Polymerase Modulate Genome Replication, Subgenomic Transcription, and Amplification of Defective Interfering RNAs

2015 ◽  
Vol 89 (6) ◽  
pp. 3236-3246 ◽  
Author(s):  
Chaminda D. Gunawardene ◽  
Karolina Jaluba ◽  
K. Andrew White
Keyword(s):  
Rna Synthesis ◽  
Mutational Analysis ◽  
Rna Virus ◽  
Plant Viruses ◽  
Comparative Sequence Analysis ◽  
Terminal Region ◽  
Viral Rna ◽  
Genome Replication ◽  
Conserved Motifs ◽  
Content Type

ABSTRACTThe replication of plus-strand RNA virus genomes is mediated by virally encoded RNA-dependent RNA polymerases (RdRps). We have investigated the role of the C-proximal region in the RdRp of tomato bushy stunt virus (TBSV) in mediating viral RNA synthesis. TBSV is the prototype species in the genusTombusvirus, familyTombusviridae, and its RdRp is responsible for replicating the viral genome, transcribing two subgenomic mRNAs, and supporting replication of defective interfering RNAs. Comparative sequence analysis of the RdRps of tombusvirids identified three highly conserved motifs in their C-proximal regions, and these sequences were subsequently targeted for mutational analysis in TBSV. The results revealed that these motifs are important for (i) synthesizing viral genomic RNA and subgenomic mRNAs, (ii) facilitating plus- and/or minus-strand synthesis, and (iii) modulatingtrans-replication of a defective interfering RNA. These motifs were also found to be conserved in other plant viruses as well as in a fungal and insect virus. The collective findings are discussed in relation to viral RNA synthesis and taxonomy.IMPORTANCELittle is currently known about the structure and function of the viral polymerases that replicate the genomes of RNA plant viruses. Tombusviruses, the prototype of the tombusvirids, have been used as model plus-strand RNA plant viruses for understanding many of the steps in the infectious process; however, their polymerases remain poorly characterized. To help address this issue, the function of the C-terminal region of the polymerase of a tombusvirus was investigated. Three conserved motifs were identified and targeted for mutational analysis. The results revealed that these polymerase motifs are important for determining what type of viral RNA is produced, facilitating different steps in viral RNA production, and amplifying subgenomic RNA replicons. Accordingly, the C-terminal region of the tombusvirus polymerase is needed for a variety of fundamental activities. Furthermore, as these motifs are also present in distantly related viruses, the significance of these results extends beyond tombusvirids.

scholarly journals Sterol Binding by the Tombusviral Replication Proteins Is Essential for Replication in Yeast and Plants

2017 ◽  
Vol 91 (7) ◽  
Author(s):  
Kai Xu ◽  
Peter D. Nagy
Keyword(s):  
Viral Replication ◽  
Virus Replication ◽  
Viral Infections ◽  
Rna Virus ◽  
Plant Cells ◽  
Membrane Microdomains ◽  
Replication Proteins ◽  
Content Type ◽  
Sterol Binding

ABSTRACT Membranous structures derived from various organelles are important for replication of plus-stranded RNA viruses. Although the important roles of co-opted host proteins in RNA virus replication have been appreciated for a decade, the equally important functions of cellular lipids in virus replication have been gaining full attention only recently. Previous work with Tomato bushy stunt tombusvirus (TBSV) in model host yeast has revealed essential roles for phosphatidylethanolamine and sterols in viral replication. To further our understanding of the role of sterols in tombusvirus replication, in this work we showed that the TBSV p33 and p92 replication proteins could bind to sterols in vitro. The sterol binding by p33 is supported by cholesterol recognition/interaction amino acid consensus (CRAC) and CARC-like sequences within the two transmembrane domains of p33. Mutagenesis of the critical Y amino acids within the CRAC and CARC sequences blocked TBSV replication in yeast and plant cells. We also showed the enrichment of sterols in the detergent-resistant membrane (DRM) fractions obtained from yeast and plant cells replicating TBSV. The DRMs could support viral RNA synthesis on both the endogenous and exogenous templates. A lipidomic approach showed the lack of enhancement of sterol levels in yeast and plant cells replicating TBSV. The data support the notion that the TBSV replication proteins are associated with sterol-rich detergent-resistant membranes in yeast and plant cells. Together, the results obtained in this study and the previously published results support the local enrichment of sterols around the viral replication proteins that is critical for TBSV replication. IMPORTANCE One intriguing aspect of viral infections is their dependence on efficient subcellular assembly platforms serving replication, virion assembly, or virus egress via budding out of infected cells. These assembly platforms might involve sterol-rich membrane microdomains, which are heterogeneous and highly dynamic nanoscale structures usurped by various viruses. Here, we demonstrate that TBSV p33 and p92 replication proteins can bind to sterol in vitro. Mutagenesis analysis of p33 within the CRAC and CARC sequences involved in sterol binding shows the important connection between the abilities of p33 to bind to sterol and to support TBSV replication in yeast and plant cells. Together, the results further strengthen the model that cellular sterols are essential as proviral lipids during viral replication.

scholarly journals Effect of the native strain of the predator Nesidiocoris tenuis Reuter and the entomopathogenic fungi Beauveria bassiana and Lecanicillium muscarium against Bemisia tabaci (Genn.) under greenhouse conditions in Tunisia

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Besma Hamrouni Assadi ◽  
Sabrine Chouikhi ◽  
Refki Ettaib ◽  
Naima Boughalleb M’hamdi ◽  
Mohamed Sadok Belkadhi
Keyword(s):  
Beauveria Bassiana ◽  
Bemisia Tabaci ◽  
Entomopathogenic Fungi ◽  
Tobacco Plant ◽  
Economic Losses ◽  
Native Strain ◽  
Lecanicillium Muscarium ◽  
Southern Tunisia ◽  
Significant Efficacy ◽  
Nesidiocoris Tenuis

Abstract Background The misuse of chemical insecticides has developed the phenomenon of habituation in the whitefly Bemisia tabaci (Gennadius) causing enormous economic losses under geothermal greenhouses in southern Tunisia. Results In order to develop means of biological control appropriate to the conditions of southern Tunisia, the efficacy of the native strain of the predator Nesidiocoris tenuis Reuter (Hemiptera: Miridae) and two entomopathogenic fungi (EPF) Beauveria bassiana and Lecanicillium muscarium was tested against Bemisia tabaci (Gennadius). Indeed, the introduction of N. tenuis in doses of 1, 2, 3, or 4 nymphs per tobacco plant infested by the whitefly led to highly significant reduction in the population of B. tabaci, than the control devoid of predator. The efficacy of N. tenuis was very high against nymphs and adults of B. tabaci at all doses per plant with a rate of 98%. Likewise, B. bassiana and L. muscarium, compared to an untreated control, showed a very significant efficacy against larvae and adults of B. tabaci. In addition, the number of live nymphs of N. tenuis treated directly or introduced on nymphs of B. tabaci treated with the EPF remained relatively high, exceeding 24.8 nymphs per cage compared to the control (28.6). Conclusions It can be concluded that the native strain of N. tenuis and the EPF tested separately were effective against B. tabaci. Their combined use appears to be possible.

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