Development of an oral vaccine delivery system for shrimp aquaculture using attenuated Listeria monocytogenes

Abstract

Shrimp aquaculture faces major challenges from viral diseases, such as the white spot syndrome virus (WSSV), leading to high mortality and economic losses. Vaccination offers a potential solution, but practical oral delivery systems remain limited. Therefore, this study aims to elucidate the feasibility of using heat-killed attenuated Listeria monocytogenes (HKALM) as a safer alternative for plasmid delivery in shrimp. A triple-layered safety approach-bacterial attenuation, a suicide mechanism, and heat-killing-was implemented to minimize environmental risks. HKALM effectively delivered plasmids into shrimp hemocytes and intestinal cells, with the green fluorescent protein used as a reporter to enable detectable gene expression. Additionally, expressing the WSSV envelope protein VP53A through HKALM significantly increased phenoloxidase activity and improved shrimp survival rates after WSSV infection. These findings suggest that HKALM offers a safer, scalable platform for oral vaccine development in shrimp aquaculture, addressing critical challenges in disease management.