Breitbart, Mya

Cannon, John

Harbeitner, Rachel

Rosario, Karyna

Schenck, Ryan

English

OA OpenAgrar repository

    88  CONTRIBUTED PAPERS Wednesday, 14:00-16:00 VIRUSES 5  Contributed paper. Wednesday, 14:00 184   Soybean aphid viruses exploit contrasting transmission strategies Diveena Vijayendran, Sijun Liu, Bryony C. Bonning Department of Entomology, Iowa State University, Ames, IA 50011 USA Address for Correspondence: bbonning@iastate.edu  The soybean aphid, Aphis glycines Matsumura, is an invasive pest of primary agricultural importance in North America. Following its introduction in 2000, soybean yields dropped 11%, with the costs of management and yield loss estimated to be $1.6 billion over a 10 year period. Soybean aphids are managed primarily by application of chemical insecticides. We identified two viruses from the soybean aphid transcriptome and small RNA data that may have potential for use in soybean aphid management: Aphid lethal paralysis virus (ALPV)-Ames (Dicistroviridae) and Aphis glycines virus (AGV; unclassified). There is evidence for the presence of ALPV-like viruses in several different insects including the bird cherry-oat aphid, Rhopalosiphum padi (Linnaeus), the honeybee Apis mellifera, and Western corn rootworm Diabrotica virgifera virgifera. AGV has a ~5 kb single stranded RNA (ssRNA) genome and forms a 30 nm particle.  The RNA-dependent RNA polymerase (RdRp) of this virus is closely related to that of Euprosterna elaeasa virus (Tetraviridae), while the AGV coat protein (CP) is similar to those of plant Sobemoviruses. Based on RT-PCR of AGV RdRP sequence, AGV-like viruses appear to be present in two other aphid species, the bird cherry-oat aphid, R. padi and the green peach aphid, Myzus persicae (Sulzer). Notably, ALPV-Ames does not appear to be vertically transmitted in the soybean aphid, while AGV is 100% vertically transmitted. The different transmission strategies of these two viruses and the implications of 100% vertical transmission will be discussed.    Contributed paper. Wednesday, 14:15 185   Characterization of mechanisms involved in the transmission of a lepidopteran densovirus Cécilia Multeau1, Doriane Mutuel 2, Manuela Rakotomanga2, Anne Kenaghan2, Clément Bousquet2, Rémy Froissart3-4, Nathalie Volkoff2 and Mylène Ogliastro2 1InVivo AgroSolutions, F-06560, Valbonne, France; 2INRA, UMR 1333 DGIMI, INRA, F-34000, Montpellier, France; 3CNRS, UMR 5290 MIVEGEC, F-34394, Montpellier, France; 4CIRAD-SupAgro, UMR 385 BGPI, F-34398, Montpellier, France Address for Correspondence: cmulteau@invivo-group.com  Densoviruses are small insect parvoviruses infectious per ingestion for several lepidopteran species. Their potential as microbial control agents led us to focus on the understanding of motors driving the transmission of densoviruses in the environment. Natural dynamic of densoviral infections was never investigated although several metagenomic studies revealed the presence of densoviruses in samples from various origins (feces from bats, mosquitoes, marine samples like urchins…). In this study, we qualitatively and quantitatively characterized direct and indirect mechanisms leading to the transmission of a model viral species, Junonia coenia densovirus, on the model host Spodoptera frugiperda. We showed that cannibalism of infected individuals and bites between infected and uninfected individuals are major events in the transmission of JcDNV while exposition to contaminated feces and/or regurgitations contributes to widely disseminate the  virus throughout a susceptible population. We also found that parasitoid wasps participate to indirect transmission of densoviruses although probably in a non-specific manner. Altogether, these results are a first step toward the construction of a dynamic transmission model for densoviruses.   Contributed paper. Wednesday, 14:30 186   Discovery of circular single-stranded DNA viruses in top insect predators Karyna Rosario1, Anisha Dayaram2, Jessica Ware3, Milen Marinov2, Mya Breitbart1, Arvind Varsani2 1College of Marine Science, University of South Florida, Florida, USA; 2School of Biological Sciences, University of Canterbury, Christchurch, New Zealand; 3School of Environmental and Biological Sciences, Rutgers University, New Jersey, USA Address for Correspondence: krosari2@mail.usf.edu  Viruses with circular single-stranded DNA (ssDNA) genomes that encode a replication initiator protein (Rep) are among the smallest viruses known to infect eukaryotic organisms. Additionally, their rapid evolution rates have led to the emergence of some of these viruses as serious pathogens. Recent research indicates that the host range of eukaryote-infecting circular Rep-encoding ssDNA (CRESS-DNA) viruses, which was previously thought to be restricted to plants and vertebrates, may include insects. To expand our knowledge of circular ssDNA viruses in invertebrates, this study surveyed CRESS-DNA viruses circulating among insect populations by targeting dragonflies (Epiprocta). Dragonflies are highly mobile top insect predators that accumulate viruses from their insect prey over space and time and, thus, can be used as ‘sampling traps’ to explore the diversity of CRESS-DNA viruses found among flying insects. Using degenerate PCR and rolling circle amplification coupled with restriction digestion, 16 CRESS-DNA viral genomes were recovered from eight different dragonfly species collected in tropical and temperate regions. Nine of the genomes are similar to cycloviruses and represent five species within this proposed genus, suggesting that cycloviruses are commonly associated with insects.  Three of the CRESS-DNA viruses share conserved genomic features with the recently described fungal virus Sclerotinia sclerotiorum hypovirulence-associated DNA virus 1. The remaining viruses are divergent species representing novel CRESS-DNA viral genera. The novelty of CRESS-DNA viruses identified in dragonflies using simple molecular techniques indicates that there is an unprecedented diversity of ssDNA viruses among insect populations.    Contributed paper. Wednesday, 14:45 187-STU   Single-stranded DNA viruses in marine crustaceans Ryan Schenck1; Karyna Rosario1; Rachel Harbeitner1; John Cannon2; Mya Breitbart1 1University of South Florida College of Marine Science, Tampa, Florida, USA; 2University of South Florida College of Medicine Department of Pediatrics, USA Address for Correspondence: ryanschenck@mail.usf.edu  Metagenomic sequencing has recently revealed the ubiquity of eukaryotic circular single-stranded DNA (ssDNA) viruses in the marine environment; however, a definitive host has not been identified for most of these viruses. Through direct examination of marine shrimp and crab species, this study surveyed the diversity of circular ssDNA viruses in economically and ecologically important crustaceans, linking these newly discovered viruses to their hosts and improving our understanding of the ecological impact of ssDNA viral infection in marine crustaceans. Viral particles were partially purified from specimen homogenates through filtration, DNA was then      89  extracted and amplified through rolling circle amplification to enrich for small circular ssDNA templates. The concatenated circular genomes were then digested with restriction enzymes and the resulting products (~1– 4 kb) were cloned and sequenced. Thirteen distinct ssDNA viral genomes were recovered from five crab species and three shrimp species. Putative encoded proteins share less than 60% identity with known viral proteins from members of the Circoviridae. The detected genomes exhibit four different genomic architectures revealing an incredible diversity of ssDNA viruses in shrimp and crabs. Ongoing work aims to propagate these viruses in insect cell lines and develop a system to assess viral infectivity and modes of transmission.    Contributed paper. Wednesday, 15:00 188   Remarkable diversity of endogenous viruses in the genome of an isopod crustacean Julien Thézé, Sébastien Leclercq, Bouziane Moumen, Richard Cordaux, Clément Gilbert Université de Poitiers, Laboratoire Ecologie et Biologie des Interactions - UMR CNRS 7267, Equipe Ecologie Evolution Symbiose, 86073 Poitiers Cedex 9, France Address for Correspondence: theze.julien@gmail.com  Recent studies in paleovirology have uncovered myriads of endogenous viral elements (EVEs) integrated in the genome of their eukaryotic hosts. These fragments result from endogenization, i.e., integration of the viral genome into the host germline genome followed by vertical inheritance. So far, most studies have used a virus-centred approach, whereby endogenous copies of a particular group of viruses were searched in all available sequenced genomes. Here we follow a host-centred approach whereby the genome of a given species (the crustacean isopod Armadillidium vulgare) is comprehensively screened for the presence of EVEs using all viral sequences available as queries. This search and downstream evolutionary analyses revealed that 56 EVEs corresponding to 11 different viral lineages belonging to 5 viral families (Bunyaviridae, Circoviridae, Parvoviridae, Nimaviridae, Totiviridae) and one viral order (Mononegavirales) became endogenized in A. vulgare. We show that viral endogenization occurred recurrently during the evolution of isopods, that A. vulgare viral lineages were involved in multiple host-switches that took place between widely divergent taxa. Furthermore, 32 A. vulgare EVEs have uninterrupted open reading frames, suggesting they result from recent endogenization of viruses likely to be currently infecting isopod populations. Overall, our work shows that isopods have been and are still infected by a large variety of viruses. It also extends the host range of several families of viruses and brings new insights into their evolution. More generally, our results underline the power of paleovirology in characterizing the viral diversity currently infecting eukaryotic taxa.    Contributed paper. Wednesday, 15:15 189   Iteraviruses (Densovirinae) from monarch and black swallowtail butterflies and slug caterpillar moths and characterization of their expression strategies Qian Yu, Max Bergoin, and Peter Tijssen INRS-Institut Armand-Frappier, 531 boul. des Prairies, Laval, QC, Canada H7V1B7 Address for correspondence: peter.tijssen@iaf.inrs.ca  Iteraviruses belong to a separate genus of the Densovirinae subfamily of the Parvoviridae family and includes three densoviruses, i.e. Casphalia extranea Densovirus (CeDNV), Dendrolimus punctatus Densovirus (DpDNV) and Bombyx mori  Densovirus (BmDNV). In this study, we used a Sequence-Independent Single-Primer Amplification (SISPA) method to detect the pathogens of larvae from three additional insect species (Papilio polyxenes, Sibine fusca and Danaus plexippus), killed by some unknown pathogen. Sequencing of the clones that were obtained and BLAST analysis revealed the existence of three previously unknown densoviruses (provisionally named PpDNV, SfDNV and DppIDV). The genome of the new densoviruses were cloned into pCR2.1-topo or pBluescript(SK-) vectors. These virus sequences (including ITRs) have high identities with CeDNV and BmDNV. The identical genome organizations indicated that these three new densoviruses should be classified in the Iteravirus genus. Together with the infectious clones of CeDNV and BmDNV, we investigated the expression strategies of five different iteraviruses (PpDNV, SfDNV, CeDNV, BmDNV, DppIDV). Total RNA was obtained both from LD cell line transfected by infectious clones of the iteraviruses and virus infected larvae (Papilio polyxenes). RACE methods were used to identify the 5’ and 3’ transcription ends. The nonstructural (NS) and structural (VP) genes were located on the same strand of the genome. The NS cassette consists of two genes with NS1 and overlapping NS2. The NS2 transcripts all start at 7 nts downstream of the NS1 start codon. Transcription starts for NS1 genes are close to the AUG of NSS1. NS and VP transcripts do not overlap. The four VPs were similarly generated by leaky scanning translation of unspliced mRNA. The VP transcripts just start 2nts downstream of the poly (A) motif for NS transcripts. Interestingly, poly (A) signals for VP transcripts all overlap with the stop codons of the VP genes.     Contributed paper. Wednesday, 15:30 190   Remarkable genetic diversity of single-stranded DNA viruses in cultured shrimps and crickets Hanh T. Pham, Qian Yu, Max Bergoin, Peter Tijssen INRS-Institut Armand-Frappier, Université du Québec, Laval, QC, Canada Address for Correspondence: peter.tijssen@iaf.inrs.ca  Single-stranded DNA viruses are among the smallest viruses and include members of the Parvoviridae and Circoviridae families (linear and circular ssDNA viruses). In the past decades, PstDNV and AdDNV have been well-known viruses that have caused a severe impact on cultured shrimps and crickets. Here, we report the discovery and genome characterization of numerous novel denso- and denso-like viruses and, for the first time, new circoviruses from these hosts. During the last years, we received many cricket samples from North America that were negative for AdDNV. However, denso-like particles have been observed by EM. Complete sequence of different viral genome have been isolated and cloned including one circular ssDNA viruses of 2.5 kb, an ambisense densovirus of 4.9 kb and a segmented brevidenso-like virus (3.3 kb). Meantime, large numbers of new ssDNA viruses were also isolated from cultured shrimp from Vietnam. Characterization of these viruses revealed 3 different, unrelated circoviruses of 1.7, 1.7 (the latter is not using the standard genetic code and may have been ingested) and 1.3 kb. We also discovered a new shrimp parvovirus of about 4.1 kb that is phylogenetically poorly related to any known parvovirus. Near-atomic structures of some cricket and shrimp parvoviruses were obtained by X-ray crystallography as well as their transcription strategy. These results demonstrate a great diversity of ssDNA-viruses infecting these economically important animals. Future work will be focused on molecular features of theses viruses for a further insight into the evolution and classification of ssDNA viruses.     

Single-stranded DNA viruses in marine crustaceans

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Single-stranded DNA viruses in marine crustaceans

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