(265a) Efficacious Polyanhydride Nanovaccines Against White Spot Syndrome Virus in Shrimp

The $10.6 billion shrimp industry is growing at approximately 10% each year. However, viral diseases, such as white spot syndrome virus (WSSV), continue to threaten the socioeconomic aspects of this industry. WSSV infection of shrimp spreads rapidly and can cause 100% mortality to farmed shrimp in 2-10 days. Currently, there is no treatment available for WSSV, and farmers rely on a large number of chemical disinfectants (e.g., iodophor, formalin) to reduce the extent of disease. While vaccination of shrimp with WSSV subunit proteins or dsRNA has been shown to be successful in preventing infection, exposure to water often leads to instability and degradation of such vaccines.

The polyanhydride nanoparticle-based platform is suitable for the encapsulation and release of a diverse range of bioactive compounds such as vaccine antigens, peptides, antibiotics, and nucleic acids. Nanoparticles composed of sebacic acid (SA), 1,6-bis-(p-carboxyphenoxy) hexane (CPH), and 1,8-bis-(p-carboxyphenoxy)-3,6-dioxaoctane (CPTEG), and their copolymers exhibit surface erosion which limits the bulk exposure to water, and therefore, enhances the stability of encapsulated payloads. The ability to tailor different copolymer chemistries also allows for tunable release kinetics. Finally, previous work has demonstrated that polyanhydride nanoparticle-based vaccines (or nanovaccines) are safe and efficacious.

In this work, polyanhydride nanovaccine formulations encapsulating a WSSV antiviral were designed for reverse gavage administration to shrimp. The polyanhydride nanovaccines demonstrated increased retention within shrimp in comparison to antiviral delivered alone. It was also observed that the nanovaccines were localized to the gills of shrimp, a point of entry for WSSV virions, confirming the pathogen-mimicking nature of the nanovaccines. In addition, examination of tissue sections via histopathology showed no adverse reactions due to nanoparticle immunization. Finally, the efficacy of the polyanhydride nanovaccines was demonstrated in vivo in response to viral challenge. Taken together, the studies described herein attest to the promise of the polyanhydride nanovaccine platform as a suitable vehicle for oral delivery of shrimp vaccines.