Development of a Novel Virus-Like Particle-Based Vaccine Against PRV-1 Suitable for DIVA Strategies

Area of Science:

• Aquaculture immunology
• Viral pathogenesis
• Vaccine development

Background:

• Piscine orthoreovirus genotype 1 (PRV-1) causes Heart and Skeletal Muscle Inflammation (HSMI) in salmonids.
• PRV-1's inability to be cultured in vitro hinders traditional vaccine development.

Purpose of the Study:

• To develop a novel virus-like particle (VLP)-based vaccine against PRV-1.
• To create a vaccine strategy allowing differentiation between infected and vaccinated animals (DIVA).

Main Methods:

• Co-expressed six PRV-1 structural proteins in insect cells using a baculovirus system to create VLPs.
• Modified the σ1 protein with a c-myc epitope tag for DIVA capability.
• Challenged Atlantic salmon and rainbow trout with PRV-1 to assess vaccine efficacy and serological response.

Main Results:

• The native VLP vaccine (VLP6n) significantly reduced PRV-1 viral loads in Atlantic salmon.
• The c-myc tagged VLP vaccine (VLP6c) induced specific antibodies against the c-myc epitope in rainbow trout.
• This allowed for differentiation between vaccinated and naturally infected fish.

Conclusions:

• VLP-based vaccines are a promising strategy for controlling PRV-1 in salmon aquaculture.
• The DIVA-compatible VLP vaccine supports serological surveillance programs for PRV-1.
• This platform advances vaccine solutions for emerging fish pathogens.