# A Distinct Defense Strategy: The Molecular Basis of WSSV Tolerance in Macrobrachium nipponense Revealed by Comparative Transcriptomics with Litopenaeus vannamei

## TL;DR

This study compares how two shrimp species respond to a deadly virus, revealing a unique defense strategy in the resistant species that could help breed more disease-resistant shrimp.

## Contribution

The study identifies a novel 'proactive homeostatic reinforcement' strategy in Macrobrachium nipponense and validates HSP70 as a key antiviral gene.

## Key findings

- Resistant Macrobrachium nipponense uses a proactive homeostatic strategy to control the virus without excessive immune activation.
- HSP70 was identified as a key gene in antiviral defense, and its knockdown increased mortality and viral load in Macrobrachium nipponense.
- Susceptible Litopenaeus vannamei either experiences systemic collapse or relies on specific immune pathways like Toll-like receptor signaling.

## Abstract

White Spot Syndrome Virus (WSSV) remains one of the most devastating pathogens in global shrimp aquaculture, causing massive economic losses annually. This study employed comparative transcriptomics to elucidate the molecular basis of the differential resistance to WSSV between the highly susceptible Pacific white shrimp (Litopenaeus vannamei) and the remarkably resistant oriental river prawn (Macrobrachium nipponense). Our analysis of gill, hepatopancreas, and muscle tissues at 24 h post-infection revealed fundamentally distinct defense strategies. The resistant M. nipponense employs a unique “proactive homeostatic reinforcement” strategy, characterized by significant enrichment of pathways central to cellular homeostasis, including signal transduction, cellular processes, and transport/catabolism. This approach, supported by coordinated up-regulation of heat shock proteins and structural genes, enables effective viral control without triggering excessive immune activation. In contrast, susceptible L. vannamei displays either widespread metabolic dysregulation leading to systemic collapse in moribund individuals or dependency on specific immune pathways (Toll-like receptor signaling and apoptosis) in survivors. Through comparative KEGG analysis, we identified heat shock protein 70 kDa (HSP70, K03283) as a key conserved gene and functionally validated its critical role in antiviral defense using RNA interference. Knockdown of HSP70 in M. nipponense significantly increased cumulative mortality and viral load, confirming its essential protective function. These findings provide novel insights into crustacean antiviral immunity and identify promising genetic targets for breeding WSSV-resistant shrimp strains, offering sustainable solutions for disease management in aquaculture.