Project Title: A novel herpes virus vector-based approach for PRRSV vaccines

Institution: South Dakota State University

Outcome/Results: Investigation into the use of a herpes simplex virus-1 vector system for the development of a PRRSV vaccine provided information for its potential use as a vector to deliver antigens and to induce immune responses in pigs.

Summary: The goal of the study was to explore the potential use of a novel herpes simplex virus-1 (HSV-1) based vector system for PRRSV vaccine development. The HSV-1 vector system is made replication defective, so viruses cannot reproduce in the host and it is safe to use in immunization. Our objective was to gather key preliminary data to determine if HSV-1 could also be used in PRRSV vaccine development. We chose to use glycoprotein 5 (Gp5) of PRRSV as a model antigen due to the extensive previous studies showing the protective efficacy of Gp5. Our results showed that HSV-1 vectored Gp5 induced immune responses in pigs. However, we did not detect any virus neutralization antibody after immunization. Furthermore, no protection against viremia was seen after virus challenge. Therefore, pigs infected with PRRS virus could still shed the virus. Overall, we provided proof-of-concept information for the ability of HSV-1 vector system to deliver antigens and to induce immune response in pigs. Future efforts should be focused on the understanding of the immunogenic properties of PRRSV structural and non-structural proteins and their biological and immunological properties in HSV-1 vector system.