Effect of Silver Nanoparticles Biosynthesized by Azolla Pinnata in Preventing Clarias Gariepinus Infection with Aeromonas Hydrophila

To counteract the infection caused by the Aeromonas hydrophila (A. hydrophila) pathogen, current study suggests adding Azolla pinnata-biosynthesized silver nanoparticles (AP-AgNPs) to fish diet. Clarias gariepinus were kept in four experimental groups: groups 1 and 2 were raised on supplemental diets at 0.6 and 0.3 mg AP-AgNPs/kg feed, whereas groups 3 and 4 were the positive and negative controls, respectively, and were fed non-supplemented feed. Following a 21-day feeding trial, lethal dose of A. hydrophila isolated from local outbreak with LD50 of 1.5×106 was administered to all groups (except the control negative). Following bacterial challenge, fish sera were biochemically investigated. Additionally, transcriptional investigations of particular immune and antioxidant-associated genes in the anterior kidneys were performed at all levels before and right after A. hydrophila challenge. Results demonstrated that fish groups treated with 0.6 and 0.3 mg AP-AgNPs/kg feed displayed survival rates of 72.22% and 44.44% against A. hydrophila with normal serum levels of both hepatic and renal indictors. However, groups 1 and 2 showed a modest increase in serum levels of triglycerides and cholesterol when compared to control negative. Further, especially following the challenge, higher serum levels of the measured lysozyme (LZM) and complement 3 (C3) were noted. Additionally, gene expression investigations revealed that the anterior kidneys of the experimental fish had up-regulated transcriptional levels of the IL-1β, MHC-IA, GPX, and SOD1 genes. This signifies that African catfish fed supplemental diet containing 0.6 mg of AP-AgNPs/kg of feed for three weeks had a higher intrinsic immune responses.