Infectious hypodermal and hematopoietic necrosis virus-like particles encapsulating VP28 double-stranded RNA protect shrimp from white spot syndrome virus

Abstract

Due to their host tissue specificity and unique physical properties that extend beyond that of other biological nano-containers, virus-like particles (VLPs) are gaining attention for their use as double-stranded RNA (dsRNA) nano-containers to control viral infections in shrimp aquaculture. In this study, we used a hypodermal and hematopoietic necrosis virus (IHHNV)-like particle to encapsulate VP28 dsRNA (VP28 dsRNA + IHHNV-VLPs) and tested it for its protection against white spot syndrome virus (WSSV). The tissue specificity of the VP28 dsRNA + IHHNV-VLPs was visualized by confocal microscopy, revealing that they were targeted to many shrimp tissues such as the thoracic muscles, gills, and connective tissues in the hepatopancreas. Interestingly, the administration of VP28 dsRNA + IHHNV-VLPs silenced the WSSV challenge better than the non-encapsulated (naked) VP28 dsRNA, which was evident by the lower VP28 gene and viral copy numbers in the tissues after the challenge. Administering VP28 dsRNA + IHHNV-VLPs also stimulated the up-regulation of many immune-related genes as early as 6 h post administration, particularly those involved in fighting WSSV infection. These dual actions of the VP28 dsRNA + IHHNV-VLPs reduced the shrimp cumulative mortality rate more than did the naked VP28 dsRNA. We therefore believe that IHHNV-VLPs can act both as nano-containers for therapeutic agents and as an immunostimulant that increases protection against WSSV infection for shrimp.