Evaluation of Imoviral® effects on early immune response in Sparus aurata challenged with Vibrio anguillarum

Background: An acute phase response (APR) was experimentally induced in Sparus aurata (Linnaeus, 1758) by intraperitoneal (IP) injection of Vibrio anguillarum to evaluate the effects of dietary supplementation with the Imoviral® complex (CRISTALFARMA) on fish growth performance and health status, through the analysis of key genes involved in the APR. Imoviral® is a blend of exclusively natural extracts, i.e. uncaria (Uncaria tomentosa), shiitake (Lentinula edodes), beta-glucan and black-currant (Ribes nigrum), whose immunostimulant and analgesic properties have already been demonstrated in humans. Methods: One hundred S. aurata specimens 12.96 ± 0.93 grams, obtained from a fish farm, were used and divided into 5 experimental groups (in duplicate). After the feeding period, an experimental IP infection with V. anguillarum was performed and the APR evaluated at different time points i.e., 1, 24, 72, and 168-hours post infection. The expression of key genes involved in immune and oxidative stress responses, including IL-1β, TNF-α, defensin, hepcidin, catalase, Copper-zinc superoxide dismutase and magnesium superoxide dismutase, Glutathione S-Transferase, TGF-β and Interleukin-10 was evaluated through RT-qPCR and compared to control groups. Results: The Imoviral® diet did not affect growth performance, as all groups showed 100% survival and no significant differences in morphometric parameters. Immune-gene modulation revealed that IVS fish exhibited early and transient upregulation of TNF-α and IL-1β, while PVS fish displayed a sustained and stronger pro-inflammatory response. Antimicrobial peptides (hepcidin, defensin) were markedly overexpressed only in PVS, whereas Imoviral® fed groups showed limited or temporally controlled changes. Oxidative-stress genes (CAT, CuZnSOD, MnSOD) were strongly induced in PVS, with IVS showing more moderated patterns. Cellular metabolism marker GST was significantly modulated across treatments, with IVS showing consistent differences, indicating a possibly more balanced oxidative and immune response under Imoviral® supplementation. Conclusion: The present findings support the hypothesis that Imoviral® may serve as a promising immunostimulant and/or antibacterial dietary supplement for farmed gilthead sea bream, providing a solid basis for future investigations in this area.