Unité de Recherche Environnement, Génomique et Protéomique, Faculté des Sciences, Université Saint-Joseph de Beyrouth-Liban, Mar Roukos, Mkalles, Beirut, Lebanon.
Université de Strasbourg, Strasbourg, France; Modèles Insectes de l'Immunité Innée, UPR 9022 du CNRS, Strasbourg, France.
Res Microbiol. 2023 Jul-Aug;174(6):104089. doi: 10.1016/j.resmic.2023.104089. Epub 2023 Jun 20.
Bacillus thuringiensis israelensis is largely regarded as the most selective, safe and ecofriendly biopesticide used for the control of insect vectors of human diseases. Bti enthomopathogenicity relies on the Cry and Cyt δ-endotoxins, produced as crystalline inclusions during sporulation. Insecticidal selectivity of Bti is mainly ascribed to the binding of the Cry toxins to receptors in the gut of target insects. However, the contribution of epithelial defenses in limiting Bti side effects in non-target species remains largely unexplored. Here, taking advantage of the genetically tractable Drosophila melanogaster model and its amenability for deciphering highly conserved innate immune defenses, we unravel a central role of the NF-κB factor Relish in the protection against the effects of ingested Bti spores in a non-susceptible host. Intriguingly, our data indicate that the Bti-induced Relish response is independent of its canonical activation downstream of peptidoglycan sensing and does not involve its longstanding role in the regulation of antimicrobial peptides encoding genes. In contrast, our data highlight a novel enterocyte specific function of Relish that is essential for preventing general septicemia following Bti oral infections strictly when producing δ-endotoxins. Altogether, our data provide novel insights into Bti-hosts interactions of prominent interest for the optimization and sustainability of insects' biocontrol strategies.
苏云金芽孢杆菌以色列亚种被广泛认为是用于控制人类疾病昆虫病媒的最具选择性、安全和环保的生物农药。Bti 的杀虫活性依赖于 Cry 和 Cyt δ-内毒素，这些毒素在孢子形成过程中作为晶状内含物产生。Bti 的杀虫选择性主要归因于 Cry 毒素与靶昆虫肠道中的受体结合。然而，上皮防御在限制非靶标物种中 Bti 副作用方面的贡献在很大程度上仍未得到探索。在这里，我们利用遗传上易于处理的黑腹果蝇模型及其破译高度保守的先天免疫防御的能力，揭示了 NF-κB 因子 Relish 在保护非易感宿主免受摄入的 Bti 孢子影响方面的核心作用。有趣的是，我们的数据表明，Bti 诱导的 Relish 反应独立于其下游肽聚糖感应的经典激活，并且不涉及其在调节抗菌肽编码基因方面的长期作用。相比之下，我们的数据强调了 Relish 的一种新型肠细胞特异性功能，该功能对于在严格产生 δ-内毒素时防止 Bti 口服感染后的全身性败血症至关重要。总的来说，我们的数据为 Bti-宿主相互作用提供了新的见解，这对于优化和维持昆虫生物防治策略具有重要意义。
