Nudiviruses in free-living and parasitic arthropods: evolutionary taxonomy.

The nudiviruses (family: Nudiviridae) are large double-stranded DNA (dsDNA) viruses that infect insects and crustaceans, and have most recently been identified from ectoparasitic members (fleas and lice). This virus family was created in 2014 and has since been expanded via the discovery of multiple novel viral candidates or accepted members, sparking the need for a new taxonomic and evolutionary overview. Using current information (including data from public databases), we construct a new comprehensive phylogeny, encompassing 49 different nudiviruses. We use this novel phylogeny to propose a new taxonomic structure of the Nudiviridae by suggesting two new viral genera (Zetanudivirus and Etanudivirus), from ectoparasitic lice. We detail novel emerging relationships between nudiviruses and their hosts, considering their evolutionary history and ecological role.

Processing of the capsid proteins of the Betachrysovirus Fusarium graminearum virus-China 9 (FgV-ch9).

While the capsid of viruses in the Alphachrysovirus genus is built of subunits of a single coat protein, the capsid of viruses grouped in the Betachrysovirus genus may consist of subunits of two different proteins. For four of these betachrysoviruses, the detected molecular weights of the putative coat proteins differ from the sizes deduced from the nucleic acid sequence. The origin of these modifications remained unclear and it was hypothesized that the coat proteins undergo unspecific degradation. In our study, we show that these modifications are based on processing steps performed by unknown factors present in extracts of several eukaryotic organisms. Furthermore, we show that the C-terminal domain of P3 is fully degraded after capsid processing and particle assembly.