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Abstract The parasitoid wasp Venturia canescens is an important biological control agent of stored products moth pests and serves as a model to study the function and evolution of domesticated endogenous viruses (DEVs). The DEVs discovered in V. canescens are known as virus-like particles (VcVLPs), which are produced using nudivirus-derived components and incorporate wasp-derived virulence proteins instead of packaged nucleic acids. Previous studies of virus-derived components in the V. canescens genome identified 53 nudivirus-like genes organized in six gene clusters and several viral pseudogenes, but how VcVLP genes are organized among wasp chromosomes following their integration in the ancestral wasp genome is largely unknown. Here, we present a chromosomal scale genome of V. canescens consisting of 11 chromosomes and 56 unplaced small scaffolds. The genome size is 290.8 Mbp with a N50 scaffold size of 24.99 Mbp. A high-quality gene set including 11,831 protein-coding genes were produced using RNA-Seq data as well as publicly available peptide sequences from related Hymenoptera. A manual annotation of genes of viral origin produced 61 intact and 19 pseudogenized nudivirus-derived genes. The genome assembly revealed that two previously identified clusters were joined into a single cluster and a total of 5 gene clusters comprising of 60 intact nudivirus-derived genes were located in three chromosomes. In contrast, pseudogenes are dispersed among 8 chromosomes with only 4 pseudogenes associated with nudivirus gene clusters. The architecture of genes encoding VcVLP components suggests it originates from a recent virus acquisition and there is a link between the processes of dispersal and pseudogenization. This high-quality genome assembly and annotation represents the first chromosome-scale assembly for parasitoid wasps associated with VLPs, and is publicly available in the National Center for Biotechnology Information Genome and RefSeq databases, providing a valuable resource for future studies of DEVs in parasitoid wasps.
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This content will become publicly available on November 20, 2026
Four nudivirus core genes present in the genome of Venturia canescens are required for virus-like particle formation and prevention of encapsulation of parasitoid wasp eggs
ABSTRACT Venturia canescensis a parasitoid wasp that harbors a domesticated endogenous virus (DEV) and parasitizes host insects likeEphestia kuehniella. TheV. canescensDEV evolved from an alphanudivirus and produces virus-like particles (VLPs) in females that protect wasp eggs from a host immune defense called encapsulation. In contrast, very few DEV genes required for VLP formation and function have been identified. In this study, we characterized fiveV. canescensDEV genes of unknown function that all nudiviruses encode. Three of these genes are single copy (OrNVorf18-like,OrNVorf61-like, andOrNVorf76-like), whileOrNVorf41-likehas expanded into a six-member family andOrNVorf47-likehas expanded into a three-member family. Sequence analysis indicated all of these genes retain essential motifs present in nudivirus homologs, while transmission electron microscopy (TEM) studies characterized the timing of VLP formation during the wasp pupal stage. RNA interference (RNAi) assays identifiedOrNVorf18-like,OrNVorf61-like,OrNVorf41-like-1,andOrNVorf41-like-2as genes that are required for normal VLP formation. Knockdown ofOrNVorf47-likefamily members did not affect VLP formation but did disable binding of VLPs toV. canescenseggs and protection against encapsulation. Disabled formation of VLPs in response to RNAi knockdown ofOrNVorf18-like,OrNVorf61-like,OrNVorf41-like-1,andOrNVorf41-like-2also resulted in wasp eggs being encapsulated. In contrast, knockdown ofOrNVorf76-likehad no effect on VLP assembly, egg binding, or encapsulation. Altogether, reported results significantly advance our understanding ofV. canescensVLP (VcVLP) formation and function. IMPORTANCEUnderstanding howV. canescenscoopted an alphanudivirus to produce VcVLPs is of interest to the study of virus evolution. Our results show that three nudivirus core genes have essential functions in VcVLP formation, while one is essential for the novel function of binding to wasp eggs and protection from encapsulation, which is the most important immune defense of insects against parasitoids.
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- Award ID(s):
- 1916788
- PAR ID:
- 10652101
- Editor(s):
- van_Oers, Monique M
- Publisher / Repository:
- The Journal of Virology
- Date Published:
- Journal Name:
- Journal of Virology
- ISSN:
- 0022-538X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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