ROS Induced by <i<Streptococcus agalactiae</i< Activate Inflammatory Responses via the TNF-α/NF-κB Signaling Pathway in Golden Pompano <i<Trachinotus ovatus</i< (Linnaeus, 1758)

<i<Streptococcus agalactiae</i< is common pathogenic bacteria in aquaculture and can cause mass mortality after fish infection. This study aimed to investigate the effects of <i<S. agalactiae</i< infection on the immune and antioxidant regulatory mechanisms of golden pompano...
Ausführliche Beschreibung

<i<Streptococcus agalactiae</i< is common pathogenic bacteria in aquaculture and can cause mass mortality after fish infection. This study aimed to investigate the effects of <i<S. agalactiae</i< infection on the immune and antioxidant regulatory mechanisms of golden pompano (<i<Trachinotus ovatus</i<). Serum and liver samples were obtained at 0, 6, 12, 24, 48, 96, and 120 h after golden pompano infection with <i<S. agalactiae</i< for enzyme activity and gene expression analyses. After infection with <i<S. agalactiae</i<, the content of reactive oxygen species (ROS) in serum was significantly increased (<i<p</i< < 0.05). Serum levels of glucose (GLU), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and malondialdehyde (MDA) increased and then decreased (<i<p</i< < 0.05), reaching a maximum at 6 h. Serum antioxidant enzyme (LZM) activity increased significantly (<i<p</i< < 0.05) and reached a maximum at 120 h. In addition, the mRNA expression levels of antioxidant genes (<i<SOD</i<, <i<CAT</i<, and <i<GPx</i<) in the liver increased and then decreased, reaching the maximum at 24 h, 48 h, and 24 h, respectively. During the experimental period, the mRNA expression levels of NF-κB-related genes of the inflammatory signaling pathway inhibitory κB (<i<IκB</i<) showed an overall decreasing trend (<i<p</i< < 0.05) and the lowest expression at 120 h, whereas the mRNA expression levels of tumor necrosis factor α (<i<TNF-α</i<), interleukin-1β (<i<IL-1β</i<), IκB kinase (<i<IKK</i<), and nuclear factor NF-κB increased significantly (<i<p</i< < 0.05) and the highest expression was at 120 h. In conclusion, these results showed that <i<S. agalactiae</i< could activate internal regulatory signaling in the liver of golden pompano to induce defense and immune responses. This study is expected to lay a foundation to develop the healthy aquaculture of golden pompano and promote a more comprehensive understanding of its disease resistance mechanisms. Ausführliche Beschreibung