Biology subjects

Leobold, M.

Publications and source records attributed to Leobold, M..

2 recordsLinked to original sources

bioRxiv2023

Discovery of new endogenous viral elements in campoplegine wasps (Ichneumonidae, Campopleginae, Campoplex) suggests a widespread nudivirus domestication event

Viral endogenization events in the genomes of parasitoid wasps have led to the production of immunosuppressive particles that are injected into the host and that either contain DNA encoding virulence effectors or virulence proteins, essential for parasitism success. In some Campopleginae (Ichneumonidae) wasps, viral endogenisation involves the production of large dsDNA ichnoviruses encoding several dozens of rep virulence genes, to the exception of Venturia canescens. Instead, V. canescens harbours an endogenous nudivirus producing Virus-Like-Particles (VLPs) in which virulence proteins are wrapped into viral envelopes. Here, we described that this nudiviral domestication event is more ancient and widespread than previously thought as we identified homologous alphanudivirus sequences in the genomes of three Campopleginae species belonging to the genera Campoplex and Rimphoctona. We showed that Campoplex capitator produces morphologically similar VLPs to those of V. canescens with almost the same viral protein content. Strikingly, the virulence proteins are however different, suggesting that VLPs allow a high versatility in the molecular strategies used by the wasps in response to host selection pressures. Furthermore, a marked expansion of serpin and rep genes is present in Campoplex capitator, with one serpin and several REP proteins identified as major VLP components using proteomics. REP proteins are also well-described virulence factors initially shown to be delivered into hosts via the expression of rep genes coded by ichnovirus DNA. In Campoplex capitator, these proteins are packaged into nudivirus-derived VLPs indicating that convergent use of virulence factors can imply endogenous viruses of different origin and with different delivery mechanisms.

evolutionary biology↗

bioRxiv2023

Convergent origin and accelerated evolution of vesicle-associated RhoGAP proteins in two unrelated parasitoid wasps

Animal venoms and other protein-based secretions that perform a variety of functions, from predation to defense, are highly complex cocktails of bioactive compounds. Gene duplication, accompanied by modification of the expression and/or function of one of the duplicates under the action of positive selection, followed by further duplication to produce multigene families of toxins is a well-documented process in venomous animals. This evolutionary model has been less described in parasitoid wasps, which use maternal fluids, including venom, to protect their eggs from encapsulation by the host immune system. Here, we evidence the convergent recruitment and accelerated evolution of two multigene families of RhoGAPs presumably involved in virulence in two unrelated parasitoid wasp species, Leptopilina boulardi (Figitidae) and Venturia canescens (Icheumonidae). In both species, these RhoGAPs are associated with vesicles that act as transport systems to deliver virulence factors, but are produced in different tissues: the venom gland in Leptopilina sp. and the ovarian calyx in V. canescens. We show that the gene encoding the cellular RacGAP1 is at the origin of the virulent RhoGAP families found in Leptopilina sp. and V. canescens. We also show that both RhoGAP families have undergone evolution under positive selection and that almost all of these RhoGAPs lost their GAP activity and GTPase binding ability due to substitutions in key amino acids. These results suggest an accelerated evolution and functional diversification of these vesicle-associated RhoGAPs in the two phylogenetically distant parasitoid species. The potential new function(s) and the exact mechanism of action of these proteins in host cells remain to be elucidated.

evolutionary biology↗