# Reeler Domain-Containing Proteins Involved in the Antibacterial Immunity of Shrimp Litopenaeus vannamei

## TL;DR

This study identifies three Reeler domain-containing proteins in shrimp that help defend against bacterial infections.

## Contribution

The discovery of LvReeler1, LvReeler2, and LvReeler3 and their role in shrimp antibacterial immunity is novel.

## Key findings

- LvReeler1, LvReeler2, and LvReeler3 are expressed in shrimp tissues and are induced by bacterial infection.
- Knocking down LvReelers increases shrimp mortality and bacterial load.
- Recombinant LvReeler proteins inhibit Vibrio species, with LvReeler3 showing the strongest effect.

## Abstract

Like other invertebrates, Litopenaeus vannamei lacks adaptive immunity and relies mainly on innate immunity for defense against foreign pathogens. In this study, three distinct Reeler domain-containing molecules were discovered in L. vannamei, designated as LvReeler1, LvReeler2, and LvReeler3. Analysis of tissue-specific expression patterns indicated that LvReeler1 showed predominant expression in the stomach, whereas LvReeler2 and LvReeler3 demonstrated peak transcriptional activity within gill tissues. The expression of these molecules was induced by Vibrio parahaemolyticus. In vivo interference with LvReelers expressions via dsRNA significantly increased the mortality rate of L. vannamei, while also leading to a marked increase in the bacterial load of V. parahaemolyticus in the gills. Additionally, recombinant proteins of LvReeler1 (rLvReeler1), LvReeler2 (rLvReeler2), and LvReeler3 (rLvReeler3) were successfully expressed in Escherichia coli. Antibacterial assays demonstrated that rLvReelers inhibited the growth of V. parahaemolyticus, Vibrio alginolyticus, and Vibrio harveyi, with rLvReeler3 exhibiting the strongest inhibitory activity. Scanning electron microscopy (SEM) observations revealed that rLvReeler3 caused bacterial aggregates to disintegrate after binding to V. parahaemolyticus and V. alginolyticus. In conclusion, LvReelers play an active role in the antimicrobial immune response of L. vannamei.