<b>Oregano essential oil reduces the virulence of </b><b><i>Vibrio parahaemolyticus</i></b><b> </b><b>causing acute hepatopancreatic necrosis disease in </b><b><i>Penaeus vannamei</i></b>

Acute Hepatopancreatic Necrosis Disease (AHPND), caused by several Vibrio species, results in high mortality rates in penaeid shrimp aquaculture worldwide. Investigated the antivirulence effects of oregano essential oil (OEO) at sub-minimum inhibitory concentrations (sub-MIC) on three virulence phenotypes (exopolysaccharide, biofilm, and swarming motility) in Vibrio parahaemolyticus, the causative agent of AHPND. The antivirulence effect of OEO was validated through a challenge test by infecting Penaeus vannamei shrimp with V. parahaemolyticus cultured with or without OEO. Additionally, transcriptomic analysis was performed to compare the transcriptional regulation of V. parahaemolyticus with and without OEO addition to identify therapeutic targets at the molecular level. All three virulence phenotypes were significantly inhibited (P &lt; 0.05) in a concentration-dependent manner. Upon in vivo challenge, the mortality of V. parahaemolyticus-infected shrimp (56 ± 5%) cultured with OEO was significantly (P &lt; 0.05) lower than that of the control group (93 ± 5%). Transcriptomic analysis revealed 89 downregulated differentially expressed genes (DEGs) associated with membrane integrity, ribosomes, motility, transport, type VI secretion system (T6SS), and enzymes involved in energy metabolism, and 94 upregulated DEGs linked to biosynthetic processes, regulatory proteins, osmoadaptation, and other molecular processes. These findings suggest that OEO acts via multiple therapeutic pathways, inhibiting V. parahaemolyticus virulence.由多种弧菌属物种引发的急性肝胰腺坏死病（Acute Hepatopancreatic Necrosis Disease, AHPND）会在全球范围内造成对虾养殖产业的高死亡率。本研究探究了亚最低抑菌浓度（sub-minimum inhibitory concentrations, sub-MIC）下的牛至精油（oregano essential oil, OEO）对副溶血性弧菌（Vibrio parahaemolyticus，AHPND的致病原）的三种毒力表型：胞外多糖、生物被膜及群集运动的抗毒力作用。通过攻毒试验验证OEO的抗毒力效果：将经OEO处理与未处理的副溶血性弧菌分别感染凡纳滨对虾（Penaeus vannamei），对比两组的死亡率。此外，本研究开展转录组分析，对比添加与未添加OEO的副溶血性弧菌的转录调控情况，以在分子层面筛选治疗靶点。实验结果显示，三种毒力表型均以浓度依赖方式被显著抑制（P < 0.05）。体内攻毒试验结果表明，经OEO预处理的副溶血性弧菌感染组的凡纳滨对虾死亡率为(56 ± 5%)，显著低于对照组的(93 ± 5%)（P < 0.05）。转录组分析显示，与未添加OEO的对照组相比，处理组中共鉴定出89个下调差异表达基因（differentially expressed genes, DEGs），这些基因与膜完整性、核糖体、运动性、转运系统、VI型分泌系统（type VI secretion system, T6SS）及能量代谢相关酶类密切相关；同时鉴定出94个上调差异表达基因，这些基因涉及生物合成过程、调控蛋白、渗透压适应及其他分子生物学过程。上述研究结果表明，OEO可通过多条治疗通路抑制副溶血性弧菌的毒力。