Plasma exosomes from viral hemorrhagic septicemia virus-infected olive flounder (Paralichthys olivaceus): Proteomic insights and wound healing effects

Extracellular vesicles (EVs) or their subtypes, such as exosomes, are valuable nano-biomolecules for immunotherapeutic, drug delivery, and diagnostic purposes. Freshwater and marine fish, including olive flounder (Paralichthys olivaceus), are highly susceptible to the contagious Viral hemorrhagic septicemia virus (VHSV). In this study, we aimed to determine how infection alters the biological responses by analyzing the proteomic profiles of plasma-derived exosomes from phosphate-buffered saline (PBS) injected (PBS-Exo) and VHSV challenged (VHSV-Exo) olive flounders at the initial stages of infection. Moreover, we demonstrate that this immunomodulatory multifunctional biomaterial possesses wound-healing effects. To understand this, the isobaric tags for relative and absolute quantitation (iTRAQ) and tandem mass spectrometry approach was applied, and differentially expressed (DE) proteins in VHSV-Exo were identified. Following VHSV infection, a total of 2399 unique peptides with 407 proteins, including 27 upregulated and 25 downregulated (q < 0.05), were identified. Compared with mock-infected PBS-Exo, the DE proteome profile of VHSV-Exo is composed of various important biological processes related to metabolic, immune responses, and wound healing. A compiled set of proteins and pathways potentially associated with infection and pathology could be considered as early infectious biomarkers. Furthermore, VHSV-Exo exhibited a stronger wound healing effect than PBS-Exo both in vitro and in vivo. These results support our aim of demonstrating their multifunctional properties to improve fish health management and sustainable aquaculture practices.