Evaluating the Protective Immunological Effects of <i>Pandanus tectorius</i> Leaf Extract Against Pathogenic <i>Vibrio campbellii</i> Using Gnotobiotic Brine Shrimp Model System

This study investigated the protective effects of Pandanus tectorius leaf extract (PLE) on the tolerance of the brine shrimp Artemia franciscana against the pathogen Vibrio campbellii . Axenic Artemia nauplii were hatched and exposed to PLE for 2 h, after which their resistance to V. campbellii was examined. Protective responses were evaluated by measuring nauplii survival and changes in the expression of key immune‐related genes, such as heat shock protein 70 ( hsp70 ), hsp60 , hsp90 , high mobility group box 1 ( hmgb1 ), prophenoloxidase ( proPO ), and transglutaminase ( tgase ) upon V. campbellii challenge. Additionally, a Vibrio colonization assay was conducted to assess PLE’s antimicrobial potential. The results revealed that 2 h pretreatment with PLE at a concentration of 1 g/L significantly improved survival against V. campbellii . Immune‐related gene expression was induced at different time points (e.g., 12–24 h) during the Vibrio challenge and the colonization assay confirmed PLE’s antimicrobial properties. The observed protection could likely be due to a combination of immune gene activation, antioxidant activity, and the antimicrobial effect of the extract. This study highlights the significance of PLE by indicating its potential to serve as a protective agent in aquaculture, enhancing the resilience of aquatic organisms against biotic stressors like vibrios.