# Hexane extract from black soldier fly prepupae: A novel immunomodulatory strategy against Aeromonas hydrophila infection in zebrafish

## TL;DR

A hexane extract from black soldier fly prepupae helps modulate the immune response in zebrafish against a bacterial infection, showing potential for use in aquaculture.

## Contribution

The study introduces a novel natural immunomodulator from black soldier fly prepupae for combating bacterial infections in fish.

## Key findings

- HEBP at 1000 mg/kg feed increased IL-4 and IL-10 expression in uninfected zebrafish.
- HEBP at 1000 mg/kg was identified as the optimal concentration for immune modulation.
- Infected zebrafish showed decreased IL-4 and IL-10 expression when treated with HEBP.

## Abstract

Aeromonas hydrophila infections in fish result in significant financial losses within aquaculture. Previous research indicates black soldier fly (BSF) prepupae provide immunomodulatory benefits through their fatty acids, chitin, and proteins. The study evaluated the impact of hexane extract from black soldier fly prepupae (HEBP) on interleukin (IL)-4 and IL-10 cytokine expression in zebrafish, both infected and uninfected with A. hydrophila.

Adult zebrafish (aged 4–5 months) was assigned to a negative control group (fed commercial feed), a positive control group (commercial feed + A. hydrophila infection at 107 colony-forming unit/mL), and three treatment groups (T1, T2, T3) that received HEBP at doses of 1000; 2000 and 4000 mg/kg feed for 30 days, respectively. A. hydrophila infection was introduced on day 31 through immersion. Analysis of IL-4 and IL-10 expression in the head kidney trunk region (body without head and tail) through quantitative polymerase chain reaction was conducted on day 33.

The HEBP modulated the immune response to A. hydrophila infection at a concentration of 1000 mg/kg feed, as evidenced by an increase in IL-4 and IL-10 expression in the groups not infected with the bacteria. However, these cytokines were decreased in the infected groups.

A feed concentration of 1000 mg/kg HEBP was identified as optimal for cytokine modulation. This discovery marks a significant advancement in the development and benefit of a natural extract-based immunomodulator in a zebrafish model, which is potentially immunotherapeutic against bacterial infections in fish for the aquaculture industry.