Evaluating control measures for Senecavirus A in the marketing chain

Authors: Buckley, Alexandra; ZANELLA, ERALDO - Oak Ridge Institute For Science And Education (ORISE); HUMPHREY, NICKI - Animal And Plant Health Inspection Service (APHIS); Lager, Kelly

Submitted to: International Pig Veterinary Society (IPVS)
Publication Type: Abstract Only
Publication Acceptance Date: 2/26/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Background and Objectives Senecavirus A (SVA) infection in swine can lead to the development of vesicular lesions indistinguishable from foot-and-mouth disease (FMD). FMD is a reportable disease; therefore, in FMD free countries, FMD must be ruled out when a vesicular lesion is observed. In the United States, many of these investigations have occurred at sow slaughter plants. The objectives of this study were to understand the environmental burden of SVA in slaughter plant lairage and evaluate the efficacy of SVA controls measures including disinfection and an autogenous vaccine. Materials and Methods Swab samples were collected from the environment of four sow slaughter plants including flooring, waterers, and gating on a regular basis between June and December of 2020. Samples were tested for SVA nucleic acid by PCR and live virus by virus isolation (VI). An isolate was selected for autogenous vaccine production and challenge virus. Weaned pigs were split into two groups: autogenous vaccine + challenge (Group 1, n=12) and sham vaccine + challenge (Group 2, n=12). Pigs were observed daily for the development of vesicular lesions. Blood and rectal swab samples collected regularly for a serum virus neutralization (VN) assay and SVA PCR. Results Three slaughter plants had positive environmental swabs with August having the highest percentage of PCR positive samples. Floor samples were the most common positive sample type. Environmental samples collected after cleaning protocols were negative for SVA. Group 1 did not have measurable neutralizing antibody titers at the time of challenge; however, only 2/12 animals in Group 1 developed vesicular lesions, while 5/12 animals in Group 2 developed lesions. Less animals in Group 1 had PCR positive rectal swabs and serum samples compared to Group 2. Discussion and Conclusion This study demonstrated that SVA can be readily found in the environment of slaughter plants; however, current cleaning protocols were able to eliminate the virus. Two doses of an inactivated autogenous SVA vaccine did not generate a robust neutralizing antibody response, though may have reduced clinical disease. Enforcement of strict biosecurity and regular cleaning in slaughter plant lairage as well as continued investigation into efficacious vaccine candidates could help control SVA spread in marketing channels.