Complete genome sequences of three novel cycloviruses identified in a dragonfly (Odonata: Anisoptera) from China

Metagenomic Identification of Viral Sequences in Laboratory Reagents

Metagenomic next-generation sequencing has transformed the discovery and diagnosis of infectious disease, with the power to characterise the complete 'infectome' (bacteria, viruses, fungi, parasites) of an individual host organism. However, the identification of novel pathogens has been complicated by widespread microbial contamination in commonly used laboratory reagents. Using total RNA sequencing ("metatranscriptomics") we documented the presence of contaminant viral sequences in multiple 'blank' negative control sequencing libraries that comprise a sterile water and reagent mix. Accordingly, we identified 14 viral sequences in 7 negative control sequencing libraries. As in previous studies, several circular replication-associated protein encoding (CRESS) DNA virus-like sequences were recovered in the blank control libraries, as well as contaminating sequences from the Totiviridae, Tombusviridae and Lentiviridae families of RNA virus. These data suggest that viral contamination of common laboratory reagents is likely commonplace and can comprise a wide variety of viruses.

Viral metagenomics revealed diverse CRESS-DNA virus genomes in faeces of forest musk deer

Background

Musk deer can produce musk which has high medicinal value and is closely related to human health. Viruses in forest musk deer both threaten the health of forest musk deer and human beings.

Methods

Using viral metagenomics we investigated the virome in 85 faeces samples collected from forest musk deer.

Results

In this article, eight novel CRESS-DNA viruses were characterized, whole genomes were 2148 nt–3852 nt in length. Phylogenetic analysis indicated that some viral genomes were part of four different groups of CRESS-DNA virus belonging in the unclassified CRESS-DNA virus, Smacoviridae, pCPa-like virus and pPAPh2-like virus. UJSL001 (MN621482), UJSL003 (MN621469) and UJSL017 (MN621476) fall into the branch of unclassified CRESS-DNA virus (CRESSV1–2), UJSL002 (MN621468), UJSL004 (MN621481) and UJSL007 (MN621470) belong to the cluster of Smacoviridae, UJSL005 (MN604398) showing close relationship with pCPa-like (pCRESS4–8) clusters and UJSL006 (MN621480) clustered into the branch of pPAPh2-like (pCRESS9) virus, respectively.

Conclusion

The virome in faeces samples of forest musk deer from Chengdu, Sichuan province, China was revealed, which further characterized the diversity of viruses in forest musk deer intestinal tract.

Diversity and Evolution of Novel Invertebrate DNA Viruses Revealed by Meta-Transcriptomics

DNA viruses comprise a wide array of genome structures and infect diverse host species. To date, most studies of DNA viruses have focused on those with the strongest disease associations. Accordingly, there has been a marked lack of sampling of DNA viruses from invertebrates. Bulk RNA sequencing has resulted in the discovery of a myriad of novel RNA viruses, and herein we used this methodology to identify actively transcribing DNA viruses in meta-transcriptomic libraries of diverse invertebrate species. Our analysis revealed high levels of phylogenetic diversity in DNA viruses, including 13 species from the Parvoviridae, Circoviridae, and Genomoviridae families of single-stranded DNA virus families, and six double-stranded DNA virus species from the Nudiviridae, Polyomaviridae, and Herpesviridae, for which few invertebrate viruses have been identified to date. By incorporating the sequence of a "blank" experimental control we also highlight the importance of reagent contamination in metagenomic studies. In sum, this work expands our knowledge of the diversity and evolution of DNA viruses and illustrates the utility of meta-transcriptomic data in identifying organisms with DNA genomes.