The discovery, distribution, and diversity of DNA viruses associated withDrosophila melanogasterin Europe

Abstract

Drosophila melanogaster is an important model for antiviral immunity in arthropods, but very few DNA viruses have been described from the family Drosophilidae. This deficiency limits our opportunity to use natural host-pathogen combinations in experimental studies, and may bias our understanding of the Drosophila virome. Here we report fourteen DNA viruses detected in a metagenomic analysis of approximately 6500 pool-sequenced Drosophila, sampled from 47 European locations between 2014 and 2016. These include three new nudiviruses, a new and divergent entomopoxvirus, a virus related to Leptopilina boulardi filamentous virus, and a virus related to Musca domestica salivary gland hypertrophy virus. We also find an endogenous genomic copy of galbut virus, a dsRNA partitivirus, segregating at very low frequency. Remarkably, we find that Drosophila Vesanto virus, a small DNA virus previously described as a bidnavirus, may be composed of up to 12 segments and thus represent a new lineage of segmented DNA viruses. Two of the DNA viruses, Drosophila Kallithea nudivirus and Drosophila Vesanto virus are relatively common, found in 2% or more of wild flies. The others are rare, with many likely to be represented by a single infected fly. We find that virus prevalence in Europe reflects the prevalence seen in publicly-available datasets, with Drosophila Kallithea nudivirus and Drosophila Vesanto virus the only ones commonly detectable in public data from wild-caught flies and large population cages, and the other viruses being rare or absent. These analyses suggest that DNA viruses are at lower prevalence than RNA viruses in D. melanogaster, and may be less likely to persist in laboratory cultures. Our findings go some way to redressing an earlier bias toward RNA virus studies in Drosophila, and lay the foundation needed to harness the power of Drosophila as a model system for the study of DNA viruses.

Fine‐scale spatial patterns of wildlife disease are common and understudied

“…Leu et al, 2020). This approach could also be applied to intensively and widely spatially distributed sampling locations, either for smaller animals such as insects (Wallace et al, 2021) or for immobile organisms like plants (Halliday et al, 2020). Finally, immunity is often quantified alongside parasite burden and prevalence, and it would be interesting to see whether spatial variation in immunity manifests on the same scale, and whether it predicts disease risk (Becker et al, 2020).…”

Fine-scale spatial patterns of wildlife disease are common and understudied

“…Leu, Sah, Krzyszczyk, Jacoby, & Mann, 2020). This approach could also be applied to intensively and widely spatially distributed sampling locations, either for smaller animals such as insects (Wallace et al, 2021) or for immobile organisms like plants (Halliday et al, 2020). Finally, immunity is often quantified alongside parasite burden and prevalence, and it would be interesting to see whether spatial variation in immunity manifests on the same scale, and whether it predicts disease risk (Becker et al, 2020).…”

First Evidence of Past and Present Interactions between Viruses and the Black Soldier Fly, Hermetia illucens

“…As a first effort to characterize the BSF virome, we searched for virus-derived sequences in publicly available genomic and transcriptomic datasets. Such an approach has proven useful when characterizing new, free circulating, exogenous viruses (EXVs), which may be co-sequenced with that of the host [22][23][24][25]. Screening host genomes may also lead to identifying endogenous viral elements (EVEs), i.e., complete or fragmented viral genomes that became integrated into the genome in the germline of their host and were vertically transmitted [23,26].…”