Moreau Sébastien J M, Marchal Lorène, Boulain Hélène, Musset Karine, Labas Valérie, Tomas Daniel, Gauthier Jérémy, Drezen Jean-Michel
Institut de Recherche sur la Biologie de l'Insecte, UMR 7261 CNRS, Université de Tours, Tours, 37000, France.
Department of Ecology and Evolution, University of Lausanne, Lausanne, 1015, Switzerland.
BMC Genomics. 2025 Apr 30;26(1):431. doi: 10.1186/s12864-025-11604-y.
Cotesia congregata is a parasitoid Hymenoptera belonging to the Braconidae family and carrying CCBV (Cotesia congregata Bracovirus), an endosymbiotic polydnavirus. CCBV virus is considered as the main virulence factor of this species, which has raised questions, over the past thirty years, about the potential roles of venom in the parasitic interaction between C. congregata and its host, Manduca sexta (Lepidoptera: Sphingidae). To investigate C. congregata venom composition, we identified genes overexpressed in the venom glands (VGs) compared to ovaries, analyzed the protein composition of this fluid and performed a detailed analysis of conserved domains of these proteins.
Of the 14 140 known genes of the C. congregata genome, 659 genes were significantly over-expressed (with 10-fold or higher changes in expression) in the VGs of female C. congregata, compared with the ovaries. We identified 30 proteins whose presence was confirmed in venom extracts by proteomic analyses. Twenty-four of these were produced as precursor molecules containing a predicted signal peptide. Six of the proteins lacked a predicted signal peptide, suggesting that venom production in C. congregata also involves non-canonical secretion mechanisms. We have also analysed 18 additional proteins and peptides of interest whose presence in venom remains uncertain, but which could play a role in VG function.
Our results show that the venom of C. congregata not only contains proteins (including several enzymes) homologous to well-known venomous compounds, but also original proteins that appear to be specific to this species. This exhaustive study sheds a new light on this venom composition, the molecular diversity of which was unexpected. These data pave the way for targeted functional analyses and to better understand the evolutionary mechanisms that have led to the formation of the venomous arsenals we observe today in parasitoid insects.
聚瘤姬蜂是膜翅目茧蜂科的一种寄生蜂，携带内共生多DNA病毒——聚瘤姬蜂茧蜂病毒（CCBV）。CCBV病毒被认为是该物种的主要毒力因子，在过去三十年里，引发了关于毒液在聚瘤姬蜂与其寄主烟草天蛾（鳞翅目：天蛾科）寄生相互作用中潜在作用的问题。为了研究聚瘤姬蜂的毒液成分，我们鉴定了与卵巢相比在毒腺（VGs）中过表达的基因，分析了这种液体的蛋白质组成，并对这些蛋白质的保守结构域进行了详细分析。
在聚瘤姬蜂基因组的14140个已知基因中，与卵巢相比，有659个基因在雌性聚瘤姬蜂的毒腺中显著过表达（表达变化10倍或更高）。我们通过蛋白质组学分析鉴定出30种在毒液提取物中存在得到证实的蛋白质。其中24种以前体分子形式产生，含有预测的信号肽。6种蛋白质缺乏预测的信号肽，这表明聚瘤姬蜂毒液的产生还涉及非经典分泌机制。我们还分析了另外18种感兴趣的蛋白质和肽，它们在毒液中的存在仍不确定，但可能在毒腺功能中发挥作用。
我们的结果表明，聚瘤姬蜂的毒液不仅含有与知名有毒化合物同源的蛋白质（包括几种酶），还含有似乎是该物种特有的原始蛋白质。这项详尽的研究为这种毒液成分带来了新的认识，其分子多样性出人意料。这些数据为有针对性的功能分析以及更好地理解导致我们今天在寄生昆虫中观察到的毒液库形成的进化机制铺平了道路。
