# Novel use of Quillaja saponaria extracts to prevent viral infections in Atlantic salmon: in vitro ISAv and IPNv inhibition and in vivo protection against IPNv

## TL;DR

This study shows that extracts from the Quillaja saponaria tree can inhibit viral infections in salmon and reduce mortality in fish.

## Contribution

The study demonstrates the in vitro and in vivo antiviral efficacy of Quillaja saponaria extracts against IPNv and ISAv in Atlantic salmon.

## Key findings

- Quillaja saponaria extracts inhibited ISAv and IPNv replication by over 90% and 60% in vitro.
- Dietary supplementation with Quillaja extracts significantly reduced IPNv-induced mortality in Atlantic salmon fry.
- The extracts show potential as natural, non-pharmacological additives for disease prevention in aquaculture.

## Abstract

The global expansion of salmon farming has increased the prevalence of viral diseases, especially Infectious Pancreatic Necrosis (IPN) and Infectious Salmon Anemia (ISA), posing significant threats to the sustainability and productivity of the industry. Extracts from the Chilean tree Quillaja saponaria Molina are a rich source of triterpenic saponins, glycosides with antimicrobial and immunomodulatory properties. This study assessed the antiviral efficacy of a non-purified (NPQ), a partially purified (PPQ, the active ingredient of PAQ-Xtract®), and a purified (VaxSap®) commercial Quillaja saponaria extracts, as dietary additives to prevent and control viral infections in Atlantic salmon (Salmo salar).

The In vitro antiviral activity of the extracts was measured through infection assay in ASK and CHSE-214 cell lines. Results were expressed as the percentage of inhibition, comparing the number of viral copies or the number of PFU produced in untreated conditions to those in Quillaja saponaria extracts treated conditions. In vivo trial were conducted on Atlantic salmon fry. During the trial, fish were fed with a standard diet and supplemented with NPQ or PPQ. Fishes were intraperitoneal challenged with IPNv and mortalitiy registered.

In vitro assays demonstrated that Quillaja extracts generated over 90 and 60% inhibition of replication of ISAv and IPNv, respectively. In vivo challenge experiments further showed that dietary supplementation with NPQ or PPQ significantly reduced cumulative mortality following IPNv infection compared with untreated controls.

These findings indicate that Quillaja saponaria extracts may be used as effective, natural, non-pharmacological additives to prevent diseases caused by these viruses. Their use supports the development of sustainable and environmentally responsible disease-management strategies in modern aquaculture.