De Stefano Marina, Barletta Giovanni Di Gregorio, Morgera Simona, De Luca Ylenia, Belaeff Chiara, Power Karen, Baccigalupi Loredana, De Vico Gionata, Conte Ivan, Ricca Ezio, Saggese Anella
Dipartimento di Biologia, Università di Napoli Federico II, Naples, Italy.
Stazione Zoologica "Anton Dohrn", Naples, Italy.
Microb Cell Fact. 2025 May 2;24(1):96. doi: 10.1186/s12934-025-02725-w.
Vibriosis is a deadly illness caused by various species of the Vibrio genus. Due to its high incidence in aquaculture plants, vibriosis is responsible for significant economic losses. Currently, anti-vibriosis treatments rely on antibiotics. However, the global rise in antibiotic resistance necessitates the development of alternative approaches. Novel vaccines and effective probiotics have been proposed as potential alternative to antibiotics in fighting bacterial infections. Here we propose a combined vaccine/probiotic strategy based on the use of probiotic bacterial spores for the oral delivery of Vibrio antigens. Spores of various species of the Bacillus genus are widely used as probiotics and have been shown to efficiently display antigens in a non-recombinant way.
Spores of various probiotic strains were analyzed to assess their effectiveness in displaying a heterologous model protein, and B. megaterium MV30 was identified as the most efficient strain. MV30 spores were then used to display two antigens of Vibrio harveyi, the entire Hsp33 protein of 33 kDa and a 239 amino acids fragment of OmpK (OmpK), identified as the most immunogenic part of the protein. While Hsp33 is a stable protein, OmpK is unstable at conditions mimicking those encountered in an aquaculture plant and the interaction with MV30 spores reduced such instability. The protective ability of the combined probiotic/vaccination strategy was assayed on Medaka fish (Oryzias latipes), as a model. In a challenge experiment with a virulent strain of Vibrio harveyi, a protective effect was observed with MV30 spores alone and such effect was significantly increased when the same spores displayed either one of the two antigens.
Our results support the use of probiotics and oral vaccines as a valid alternative to antibiotics and point to the application of probiotic spore-based antigen delivery as a novel strategy to fight pathogenic infections.
弧菌病是由弧菌属的多种细菌引起的致命疾病。由于其在水产养殖厂中的高发病率，弧菌病造成了重大经济损失。目前，抗弧菌病治疗依赖于抗生素。然而，全球抗生素耐药性的上升使得开发替代方法成为必要。新型疫苗和有效的益生菌已被提议作为对抗细菌感染的抗生素的潜在替代品。在此，我们提出一种基于使用益生菌芽孢进行弧菌抗原口服递送的联合疫苗/益生菌策略。芽孢杆菌属的多种芽孢被广泛用作益生菌，并已证明能以非重组方式有效展示抗原。
分析了各种益生菌菌株的芽孢，以评估它们展示异源模型蛋白的有效性，巨大芽孢杆菌MV30被确定为最有效的菌株。然后使用MV30芽孢展示哈维氏弧菌的两种抗原，即33 kDa的完整Hsp33蛋白和OmpK（外膜孔蛋白K）的239个氨基酸片段，该片段被确定为该蛋白最具免疫原性的部分。虽然Hsp33是一种稳定的蛋白，但OmpK在模拟水产养殖厂环境的条件下不稳定，与MV30芽孢的相互作用降低了这种不稳定性。以青鳉鱼（日本青鳉）为模型，对联合益生菌/疫苗接种策略的保护能力进行了测定。在一项用哈维氏弧菌强毒株进行的攻毒实验中，单独使用MV30芽孢观察到了保护作用，当相同的芽孢展示两种抗原中的任何一种时，这种作用显著增强。
我们的结果支持使用益生菌和口服疫苗作为抗生素的有效替代品，并指出基于益生菌芽孢的抗原递送作为对抗致病性感染的新策略的应用。
