Fish Defensin Peptides Fight Both Viruses and Bacteria in European Sea Bass | Research

The takeaway

Beta-defensins in European sea bass are upregulated during viral infection and demonstrate direct antiviral and antibacterial activity, revealing their dual-function immune role in fish.

Dual antiviral + antibacterial
Beta-defensins showed direct killing activity against both pathogen types

What the researchers found

European sea bass beta-defensins (bdef1 and bdef2) are upregulated by betanodavirus infection and possess direct antiviral activity in addition to their known antibacterial functions.

Why it matters

Understanding fish antimicrobial peptides helps develop disease-resistant aquaculture stocks and may reveal conserved immune mechanisms relevant to human defensin biology and peptide-based therapeutics.

How the study worked

Laboratory study examining gene regulation, protein expression, and functional assays of beta-defensins in European sea bass during viral infection.

What this study cannot tell us

In vitro functional assays may not fully reflect in vivo immune dynamics; single fish species studied; redox state effects on function need further characterization.

How to read the evidence

Laboratory study with gene expression and functional assays — strong mechanistic evidence in a fish model.

When this study was published

Published in 2026, reflecting current research into fish antimicrobial peptide biology.

The bigger picture

Defensins are an ancient immune defense conserved from fish to humans. Understanding how fish defensins fight viruses could inform both aquaculture disease management and the development of broad-spectrum antimicrobial peptides for human medicine.

Questions still open

Could fish beta-defensins be developed as therapeutic antiviral agents for aquaculture?
Do similar dual antiviral-antibacterial mechanisms exist in human beta-defensins?

Common questions

What are beta-defensins?

Beta-defensins are small antimicrobial peptides produced by the immune system that can directly kill pathogens by disrupting their membranes. They are found in species from fish to humans as part of innate immunity.

Why study antimicrobial peptides in fish?

Fish are a major food source globally, and viral diseases devastate aquaculture. Understanding natural immune defenses like defensins could help breed disease-resistant fish or develop peptide-based treatments.

Read the original research

European sea bass beta-defensins are regulated by betanodavirus infection and show direct antiviral and antibacterial functions.

Fish & shellfish immunology, 169, 111048

View on PubMed ↗Publisher’s paper ↗

Citation

Cervera, Laura; Valero, Yulema; Hernández-Ariola, Elena; Cárdenas, Constanza; Guzman, Fanny; Mercado, Luis; Chaves-Pozo, Elena; Cuesta, Alberto. (2026). European sea bass beta-defensins are regulated by betanodavirus infection and show direct antiviral and antibacterial functions.. Fish & shellfish immunology, 169, 111048. https://doi.org/10.1016/j.fsi.2025.111048