First Litopenaeus vannamei WSSV 100% oral vaccination protection using CotC::Vp26 fusion protein displayed on Bacillus subtilis spores surface.

Aims: Litopenaeus vannamei do not have an adaptive immune response system. White spot syndrome virus (WSSV) is the most severe pathogen in shrimps. Bacillus subtilis spores carrying heterologous antigens on its surface have been evaluated as a vaccine inducing specific systemic responses on vertebrates. Orally administrated Vp28 vaccines have been investigated in crustaceans. Vp26 is also an important constituent of WSSV structure but little is known about its oral vaccination capacity in L. vannamei. Methods and Results: In this study, for first time, L. vannamei WSSV protection was carried out using B. subtilis recombinant spores (RS), displaying CotC::Vp26 fusion protein (FP) on its surface. RS-expressing FP were coated on shrimp food pellets and used to feed L. vannamei. Results have shown that orally administered B. subtilis RS protected 100% L. vannamei against WSSV infection. Conclusions: Bacillus subtilis spores orally administrated expressing CotC:: Vp26 fusion protein on its surface demonstrated the great capacity of Vp26 to induce immune protection, equally or even greater than Vp28 in L. vannamei. Significance and Impact of the Study: The biotechnological process developed represents an easy to produce, practical to handle, environmentally stable, human-safe and economically feasible opportunity to apply a new Vp26 vaccine in a massively way in shrimp farms.