Hepcidin and dicentracin peptides show preventive antiviral applications against NNV infection in European sea bass through immunomodulatory roles

Aquaculture is an extremely prosperous market threatened by pathogen outbreaks, including viruses as nodavirus (NNV), which infect fish species with special interest in trading such as European sea bass. Antimicrobial peptides (AMPs) might constitute potential antiviral agents, which had been previously evaluated in fish with positive prospects, based on their properties as immunomodulators or directly killing pathogens. In this line, we aimed to evaluate this dual role by administering two European sea bass synthetic AMPs (Hamp or Dic) prior to NNV infection. Both treatments conferred partial protection against NNV though viral replication and load were not affected. Both AMPs elicited, prior to infection, AMP response and leukocyte mobilization whilst downregulated pro-inflammatory markers. Upon infection, Hamp and Dic peptides abrogated the inflammatory response provoked by NNV as well as avoid NNV-induced disturbance of the leucocyte distribution in the brain, mainly neutrophils, macrophages and CD8+ T cells. This study points that preventive applications of synthetic Hamp and Dic peptides exert their antiviral actions through the immunomodulatory role and not by a direct action of the antimicrobial on NNV. This work opens the door to the use of AMPs as potential prophylactic tools against NNV as well as immunostimulant in fish farms.