Targeting Essential Genes Utilizing RNA Interference to Protect the Ailing Shrimp Industry Against WSSV

Shrimps are indispensable source of income in major producing countries worldwide. The irreversible destruction caused by White Spot Syndrome Virus (WSSV) in shrimp farms around Asia prompted for a research on how to impede further damages brought about by this viral pathogen in the shrimp industry. To date, there are no effective strategies to combat WSSV infection. Hence, functional studies on genes critical for viral reflection, is essential in elucidating shrimp-virus interaction. Here we report two genes speculated to be crucial in viral infection: VP9, coding for a non-structural protein and contig23 (c23), a DNA fragment found in shrimp, identified to have high homology with WSSVORF-325.

Utilizing dsRNA-mediated RNA interference, we showed the involvement of VP9 and c23 in the infectivity of WSSV in giant freshwater prawn, Macrobrachium rosenbergii.  Silencing of VP9 and contig C23 effectively silenced other regions of the WSSV genome. Significant survival rate for the C23- and VP9-dsRNA treatment compared to the GFP-dsRNA and PBS was recorded. Silencing of VP9 and C23 also inhibited other WSSV region and the high survival rate highlights the involvement of both genes in the infectivity of WSSV in shrimp. Moreover, VP9 and C23 proved to be effective in combating WSSV infection in at least 3 different shrimp species; Marsupenaeus japonicus, Penaeus monodon and Macrobrachium rosenbergii.  Targeting specific genes for RNAi therapeutics might pave the way for the effective management if not eradication of WSSV infection.