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Lay CL, Shi M, Buček A, Bourguignon T, Lo N, Holmes EC. Unmapped RNA Virus Diversity in Termites and their Symbionts. Viruses 2020; 12:v12101145. [PMID: 33050289 PMCID: PMC7650761 DOI: 10.3390/v12101145] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/01/2020] [Accepted: 10/05/2020] [Indexed: 12/15/2022] Open
Abstract
Despite their ecological importance, nothing is known about the diversity and abundance of RNA viruses in termites (Termitoidae). We used a metatranscriptomics approach to determine the RNA virome structure of 50 diverse species of termite that differ in both phylogenetic position and colony composition. From these samples, we identified 67 novel RNA viruses, characterized their genomes, quantified their abundance and inferred their evolutionary history. These viruses were found within or similar to those from the Togaviridae, Iflaviridae, Polycipiviridae, Flaviviridae, Leviviridae, Narnaviridae, Mitoviridae, Lispivirdae, Phasmaviridae, Picobirnaviridae and Partitiviridae. However, all viruses identified were novel and divergent, exhibiting only 20% to 45% amino acid identity to previously identified viruses. Our analysis suggested that 17 of the viruses identified were termite-infecting, with the remainder likely associated with the termite microbiome or diet. Unclassified sobemo-like and bunya-like viruses dominated termite viromes, while most of the phylogenetic diversity was provided by the picobirna- and mitovirus-like viruses. Of note was the identification of a novel flavi-like virus most closely related to those found in marine vertebrates and invertebrates. Notably, the sampling procedure had the strongest association with virome composition, with greater RNA virome diversity in libraries prepared from whole termite bodies than those that only sampled heads.
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Affiliation(s)
- Callum Le Lay
- Marie Bashir Institute for Infectious Diseases and Biosecurity, The University of Sydney, Sydney 2006, New South Wales, Australia; (C.L.L.); (M.S.)
- School of Life and Environmental Sciences, The University of Sydney, Sydney 2006, New South Wales, Australia;
- School of Medical Sciences, The University of Sydney, Sydney 2006, New South Wales, Australia
| | - Mang Shi
- Marie Bashir Institute for Infectious Diseases and Biosecurity, The University of Sydney, Sydney 2006, New South Wales, Australia; (C.L.L.); (M.S.)
- School of Life and Environmental Sciences, The University of Sydney, Sydney 2006, New South Wales, Australia;
- School of Medical Sciences, The University of Sydney, Sydney 2006, New South Wales, Australia
| | - Aleš Buček
- Okinawa Institute of Science and Technology Graduate University, Tancha, Onna-son, Okinawa 904-0495, Japan; (A.B.); (T.B.)
| | - Thomas Bourguignon
- Okinawa Institute of Science and Technology Graduate University, Tancha, Onna-son, Okinawa 904-0495, Japan; (A.B.); (T.B.)
- Faculty of Tropical AgriSciences, Czech University of Life Sciences, 165 00 Prague, Czech Republic
| | - Nathan Lo
- School of Life and Environmental Sciences, The University of Sydney, Sydney 2006, New South Wales, Australia;
| | - Edward C. Holmes
- Marie Bashir Institute for Infectious Diseases and Biosecurity, The University of Sydney, Sydney 2006, New South Wales, Australia; (C.L.L.); (M.S.)
- School of Life and Environmental Sciences, The University of Sydney, Sydney 2006, New South Wales, Australia;
- School of Medical Sciences, The University of Sydney, Sydney 2006, New South Wales, Australia
- Correspondence:
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Nigg JC, Falk BW. Diaphorina citri densovirus is a persistently infecting virus with a hybrid genome organization and unique transcription strategy. J Gen Virol 2019; 101:226-239. [PMID: 31855134 DOI: 10.1099/jgv.0.001371] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Diaphorina citri densovirus (DcDV) is an ambisense densovirus with a 5071 nt genome. Phylogenetic analysis places DcDV in an intermediate position between those in the Ambidensovirus and Iteradensovirus genera, a finding that is consistent with the observation that DcDV possesses an Iteradensoviris-like non-structural (NS) protein-gene cassette, but a capsid-protein (VP) gene cassette resembling those of other ambisense densoviruses. DcDV is maternally transmitted to 100 % of the progeny of infected female Diaphorina citri, and the progeny of infected females carry DcDV as a persistent infection without outward phenotypic effects. We were unable to infect naïve individuals by oral inoculation, however low levels of transient viral replication are detected following intrathoracic injection of DcDV virions into uninfected D. citri insects. Transcript mapping indicates that DcDV produces one transcript each from the NS and VP gene cassettes and that these transcripts are polyadenylated at internal sites to produce a ~2.2 kb transcript encoding the NS proteins and a ~2.4 kb transcript encoding the VP proteins. Additionally, we found that transcriptional readthrough leads to the production of longer non-canonical transcripts from both genomic strands.
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Affiliation(s)
- Jared C Nigg
- Department of Plant Pathology, University of California, Davis, CA, USA
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The Acheta domesticus densovirus, isolated from the European house cricket, has evolved an expression strategy unique among parvoviruses. J Virol 2011; 85:10069-78. [PMID: 21775445 DOI: 10.1128/jvi.00625-11] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Acheta domesticus densovirus (AdDNV), isolated from crickets, has been endemic in Europe for at least 35 years. Severe epizootics have also been observed in American commercial rearings since 2009 and 2010. The AdDNV genome was cloned and sequenced for this study. The transcription map showed that splicing occurred in both the nonstructural (NS) and capsid protein (VP) multicistronic RNAs. The splicing pattern of NS mRNA predicted 3 nonstructural proteins (NS1 [576 codons], NS2 [286 codons], and NS3 [213 codons]). The VP gene cassette contained two VP open reading frames (ORFs), of 597 (ORF-A) and 268 (ORF-B) codons. The VP2 sequence was shown by N-terminal Edman degradation and mass spectrometry to correspond with ORF-A. Mass spectrometry, sequencing, and Western blotting of baculovirus-expressed VPs versus native structural proteins demonstrated that the VP1 structural protein was generated by joining ORF-A and -B via splicing (splice II), eliminating the N terminus of VP2. This splice resulted in a nested set of VP1 (816 codons), VP3 (467 codons), and VP4 (429 codons) structural proteins. In contrast, the two splices within ORF-B (Ia and Ib) removed the donor site of intron II and resulted in VP2, VP3, and VP4 expression. ORF-B may also code for several nonstructural proteins, of 268, 233, and 158 codons. The small ORF-B contains the coding sequence for a phospholipase A2 motif found in VP1, which was shown previously to be critical for cellular uptake of the virus. These splicing features are unique among parvoviruses and define a new genus of ambisense densoviruses.
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