Location: Virus and Prion ResearchTitle: Evaluation of one versus two doses of an inactivated Seneca Valley virus vaccine in weaned pigs
Submitted to: American Association of Swine Veterinarians Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 11/15/2021
Publication Date: 2/27/2022
Citation: Hoffman, K., Lager, K.M., Devries, A.C. 2022. Evaluation of one versus two doses of an inactivated Seneca Valley virus vaccine in weaned pigs. American Association of Swine Veterinarians Annual Meeting. 2022 Mar 15;40(12):1747-1754. https://doi.org/10.54846/am2022/114.
Technical Abstract: Introduction Senecavirus A (SVA), also known as Seneca Valley virus, is the causative agent of an emerging vesicular disease in swine that is clinically indistinguishable from several vesicular diseases of swine, including foot-and-mouth disease. Due to the risks associated with the establishment of foreign animal pathogens in the United States, an epidemiological investigation is required when a vesicular lesion is observed. These investigations impart a substantial economic burden on local and federal resources. An efficacious vaccine could reduce the number of these investigations being performed. Previous work has shown the effectiveness of two doses of an inactivated SVA vaccine, but administering one dose of vaccine could be more practical to implement in industry; therefore the objective of this study was to evaluate the efficacy of one dose of a whole-virus inactivated vaccine for the control of SVA. Materials and Methods Weaned pigs were randomly placed into 4 groups: Group 1 (one dose + sham challenge, n = 12), Group 2 (one dose + challenge, n = 12), Group 3 (two dose + challenge, n = 12), Group 4 (sham vax + challenge, n = 12). All pigs were vaccinated intramuscularly (IM) with 2 mL of either whole-virus inactivated SVA (2020 isolate) and adjuvant or media and adjuvant. Those groups receiving two doses had three weeks between each dose. Subsequently, two weeks after each group’s final dose, pigs were challenged intranasally with either a 2020 SVA isolate (107 TCID50/mL) or sham media. Pigs were rectal swabbed and checked for clinical signs on 0-7, 9, 11, 14, 18, and 21 days post challenge (dpc). Serum was collected from animals on -35, -14, 0, 3, 5, 7, 14 and 21 dpc. Serum and swabs were tested for SVA nucleic acid by PCR. Sera was tested by virus neutralization assay and by western blot to monitor antibody responses to SVA. Results Results are pending as the vaccine study is currently ongoing. Previous research from this group has demonstrated the efficacy of two doses of an inactivated SVA vaccine against challenge with a 2015 SVA isolate. In those vaccinated animals, neutralization titers were observed after the first dose; however, neutralization titers were significantly higher after the second dose. Currently, the neutralizing titer that correlates with protection against SVA challenge is unknown. We hypothesize that one dose of a whole-virus inactivated SVA vaccine will protect pigs against clinical disease and reduce or eliminate viral shedding. Conclusion An effective single-dose inactivated SVA vaccine would be economical and easier to apply in the field. Further, an effective inactivated SVA vaccine would provide a positive impact on the welfare of swine and reduce economic costs due to foreign animal disease investigations.