Ampelopsis japonica enhances the resistance of Chinese soft-shelled turtles (Pelodiscus sinensis) to Aeromonas veronii by inhibiting bacterial infection

Ampelopsis japonica (AJ) is an effective antibacterial agent widely used in humans and animals. However, the application of AJ in aquaculture animals remains largely unknown. In this study, we investigated the in vitro antibacterial activity of AJ against Aeromonas veronii ( A. veronii ) and evaluated its effects as a dietary supplement on intestinal health and disease resistance in Chinese soft-shelled turtles. The results showed that AJ significantly inhibited the growth of A. veronii and reduced the expression of virulence genes in vitro at a concentration of 25 mg/mL. Dietary supplementation with AJ at 1250 mg/kg significantly enhanced T-AOC and sIgA levels while reducing MPO and NO levels, as well as the expression of proinflammatory cytokines (TNF-α, IL-6, and IL-18), thereby promoting immune homeostasis. Furthermore, following A. veronii challenge, AJ supplementation maintained intestinal barrier integrity, sustained sIgA secretion, and reduced apoptosis by mitigating excessive inflammation and oxidative damage. In addition, AJ supplementation increased the expression of complement and coagulation related genes ( F3 , F5 , FGG , C3 , and C9 ), promoting the formation of membrane attack complexes (MAC, C5b-9) to eliminate pathogens. Overall, these findings indicate that AJ can be used as a functional feed additive to improve intestinal health and enhance resistance to A. veronii infection in Chinese soft-shelled turtles.