ORCID Profile
0000-0002-9844-8692
Current Organisation
University of Sydney
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Publisher: Oxford University Press (OUP)
Date: 2022
DOI: 10.1093/VE/VEAC055
Abstract: The RNA virus phylum Lenarviricota is composed of the fungi-associated families Narnaviridae and Mitoviridae, the RNA bacteriophage Leviviridae, and the plant and fungi-associated Botourmiaviridae. Members of the Lenarviricota are abundant in most environments and boast remarkable phylogenetic and genomic ersity. As this phylum includes both RNA bacteriophage and fungi- and plant-associated species, the Lenarviricota likely mark a major evolutionary transition between those RNA viruses associated with prokaryotes and eukaryotes. Despite the remarkable expansion of this phylum following metagenomic studies, the phylogenetic relationships among the families within the Lenarviricota remain uncertain. Utilising a large data set of relevant viral sequences, we performed phylogenetic and genomic analyses to resolve the complex evolutionary history within this phylum and identify patterns in the evolution of virus genome organisation. Despite limitations reflecting very high levels of sequence ersity, our phylogenetic analyses suggest that the Leviviridae comprise the basal lineage within the Lenarviricota. Our phylogenetic results also support the construction of a new virus family—the Narliviridae—comprising a set of erse and phylogenetically distinct species, including a number of uniquely encapsidated viruses. We propose a taxonomic restructuring within the Lenarviricota to better reflect the phylogenetic relationships documented here, with the Botourmiaviridae and Narliviridae combined into the order Ourlivirales, the Narnaviridae remaining in the order Wolframvirales, and these orders combined into the single class, the Amabiliviricetes. In sum, this study provides insights into the complex evolutionary relationships among the erse families that make up the Lenarviricota.
Publisher: Elsevier BV
Date: 10-2023
Publisher: Oxford University Press (OUP)
Date: 07-2022
DOI: 10.1093/VE/VEAC082
Abstract: Despite a rapid expansion in the number of documented viruses following the advent of metagenomic sequencing, the identification and annotation of highly ergent RNA viruses remain challenging, particularly from poorly characterized hosts and environmental s les. Protein structures are more conserved than primary sequence data, such that structure-based comparisons provide an opportunity to reveal the viral ‘dusk matter’: viral sequences with low, but detectable, levels of sequence identity to known viruses with available protein structures. Here, we present a new open computational resource—RdRp-scan—that contains a standardized bioinformatic toolkit to identify and annotate ergent RNA viruses in metagenomic sequence data based on the detection of RNA-dependent RNA polymerase (RdRp) sequences. By combining RdRp-specific hidden Markov models (HMMs) and structural comparisons, we show that RdRp-scan can efficiently detect RdRp sequences with identity levels as low as 10 per cent to those from known viruses and not identifiable using standard sequence-to-sequence comparisons. In addition, to facilitate the annotation and placement of newly detected and ergent virus-like sequences into the ersity of RNA viruses, RdRp-scan provides new custom and curated databases of viral RdRp sequences and core motifs, as well as pre-built RdRp multiple sequence alignments. In parallel, our analysis of the sequence ersity detected by the RdRp-scan revealed that while most of the taxonomically unassigned RdRps fell into pre-established clusters, some fell into potentially new orders of RNA viruses related to the Wolframvirales and Tolivirales. Finally, a survey of the conserved A, B, and C RdRp motifs within the RdRp-scan sequence database revealed additional variations of both sequence and position that might provide new insights into the structure, function, and evolution of viral polymerases.
Publisher: Springer Science and Business Media LLC
Date: 28-07-2022
DOI: 10.1038/S41564-022-01180-2
Abstract: Environmental RNA viruses are ubiquitous and erse, and probably have important ecological and biogeochemical impacts. Understanding the global ersity of RNA viruses is limited by s ling biases, dependence on cell culture and PCR for virus discovery, and a focus on viruses pathogenic to humans or economically important animals and plants. To address this knowledge gap, we generated metatranscriptomic sequence data from 32 erse environments in 16 provinces and regions of China. We identified 6,624 putatively novel virus operational taxonomic units from soil, sediment and faecal s les, greatly expanding known ersity of the RNA virosphere. These newly identified viruses included positive-sense, negative-sense and double-strand RNA viruses from at least 62 families. Sediments and animal faeces were rich sources of viruses. Virome compositions were affected by local environmental factors, including organic content and eukaryote species abundance. Notably, environmental factors had a greater impact on the abundance and ersity of plant, fungal and bacterial viruses than of animal viromes. Our data confirm that RNA viruses are an integral part of both terrestrial and aquatic ecosystems.
No related grants have been discovered for Sabrina Sadiq.