Double-stranded RNA delivery through soaking stimulates antiviral responses in shrimp

Shrimp rely on innate immunity to defend against viral infections. Recently, dsRNA-mediated technology has emerged as a promising tool for virus control in shrimp. While injection and feeding methods effectively inhibit viral replication, they are unsuitable for post-larval shrimp. This study evaluates the potential of soaking shrimp in dsRNA solution to activate RNA interference (RNAi) and enhance antiviral immunity against White Spot Syndrome Virus (WSSV). Shrimp were soaked in dsRNA targeting clathrin heavy chain (dsCHC) or green fluorescent protein (dsGFP) for 3 h. RNAi-related genes (Sid1, Dicer2, Ago2) were upregulated, although specific mRNA silencing was not detected. The induction of these components significantly enhanced RNAi efficacy. Additionally, non-specific antiviral gene, like IRF, was elevated. When pre-soaked shrimp were challenged with WSSV, virus levels in the gills decreased by 87 % in the low-dose group, and cumulative mortality reduced from 47 % in the control group to 16.6 %. In the high-dose group, mortality decreased significantly within the first two days, despite all shrimp succumbing by day 7. The results suggest that while specific mRNA silencing by dsRNA soaking was not observed, the dsRNA was capable of activating shrimp antiviral responses, including RNAi and non-specific immunity, leading to a significant reduction in virus levels and shrimp mortality from WSSV infection.