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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Virus and Prion Research » Research » Publications at this Location » Publication #409724
Research Project: Intervention Strategies to Control Endemic and New Emerging and Re-Emerging Viral Diseases of Swine

Location: Virus and Prion Research

Title: Validation of a live-virus PRRSV vaccine candidate for efficient attenuation and better protection

Author
item MILLER, LAURA - Kansas State University
item Anderson, Sarah
item Buckley, Alexandra
item SCHIRTZINGER, ERIN - Kansas State University
item Sarlo Davila, Kaitlyn
item Fleming, Damarius
item VAN GEELEN, ALBERT - Animal And Plant Health Inspection Service (APHIS)
item Lager, Kelly
item LI, JIUYI - Tennessee State University
item SANG, YOUNGMING - Tennessee State University

Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 11/26/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Porcine reproductive and respiratory syndrome (PRRS) is a complex and costly disease in the swine industry, due in part to the high degree of genetic variation among PRRS virus (PRRSV) field isolates. Although there are PRRSV vaccines currently available, they can have varying degrees of cross-protection depending on genetic similarity. OBJECTIVE: We have identified several host interferons that have superior antiviral properties potentiating immune responses in pigs. Preliminary evaluation of selected interferons (IFNs) was demonstrated in vitro through reverse genetic incorporation into the Type 2 PRRSV p129 vaccine backbone (Zoetis). We performed in vivo studies in pigs to compare novel vaccine candidates to commercially available MLV vaccines using a contemporary challenge virus (NADC-34). Here, we present the clinical data. METHODS: The animal study was conducted in commercial pigs (n = 10/group): sham vaccine + sham challenge, sham vaccine + challenge, MLV-commercial + challenge, MLV-PRRSVp129-IFN-omega + challenge, MLV-PRRSVp129-IFNmix + challenge. Pigs in all treatment groups were monitored for clinical signs, weighed, and temperature recorded throughout the study. Serum was collected to evaluate viral load with real-time-RT-PCR and the immune response with a commercial PRRSV ELISA, and whole blood was used to evaluate gene expression. RESULTS: The pilot study demonstrated that antiviral IFN vaccine prototype efficacy was comparable to commercially available PRRSV MLV vaccine. In this study, pigs administered the novel vaccines had similar ELISA titers prior to challenge and reduction in viral load in the serum after challenge to those given the commercial MLV. In addition, the MLV-PRRSVp129-IFNmix numerically reduced temperature and viral load greater than MLV-PRRSVp129-IFN-omega. CONCLUSION: A DNA-launched reverse genetics system for PRRSV and co-expression of immunomodulatory peptides designed to directly reverse PRRSV suppression on the pig's IFN signaling and associated immune response has the potential to enhance vaccine efficacy against heterologous PRRSV strains compared to currently available vaccines.