Infectious dose of a 2018 Senecavirus A isolate in neonatal pigs

Authors: Devries, Alexandra; Arruda, Bailey; Hau, Samantha

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/13/2026
Publication Date: 2/18/2026
Citation: Devries, A.C., Arruda, B.L., Hau, S.J. 2026. Infectious dose of a 2018 Senecavirus A isolate in neonatal pigs. PLOS ONE. https://doi.org/10.3390/vetsci13020197.
DOI: https://doi.org/10.3390/vetsci13020197

Interpretive Summary: Senecavirus A (SVA) causes vesicular disease in swine and has been associated with increased loss of suckling piglets during outbreaks on sow farms. Although SVA had only been detected sporadically in the United States since the 1980s, there was a significant increase in the number of cases in the United States and around the world starting in 2015. The cause of this change in the epidemiology of SVA remains unknown; however, changes in the infectivity of the virus could have played a role. Previous work has documented the infectious dose of a 2011 SVA isolate (SVA/CAN/2011) in neonates. The goal of this study was to determine the infectious dose of a post-2015 SVA isolate in neonatal pigs and compare its infectivity to the 2011 SVA isolate. The minimum infectious dose for SVA/KS/2018 in neonates was 316 TCID50/ml (10^2.5 TCID50/ml). This value is similar to the infectious dose determined for SVA/CAN/2011, thus providing evidence that the increase in SVA detections was not due to increases in infectivity of contemporary isolates. Pigs inoculated with higher doses of SVA/KS/2018 developed diarrhea and some animals had to be euthanized; however, pathogenic bacteria were isolated from gastrointestinal tract of these animals, which may have contributed to disease development. Additional work is needed to further characterize the role of SVA in neonatal death. This work has also demonstrated that biosecurity measures in the field to decrease viral exposure could aide in reducing the severity of infection and spread on the farm. Understanding the minimum infectious dose of SVA can help producers and veterinarians in the swine industry focus disease control and biosecurity measures on areas that carry the most risk of exposure of high levels of SVA.

Technical Abstract: Senecavirus A (SVA) is a picornavirus that causes vesicular disease in swine and has been associated with increased neonatal mortality. Although SVA had only been detected sporadically in the United States since the 1980s, there was a significant increase in the number of cases in the United States and around the world starting in 2015. The cause of this change in the epidemiology of SVA remains unknown; however, changes in the infectivity of the virus could have played a role. Previous work has documented the infectious dose of a 2011 SVA isolate (SVA/CAN/2011) in both market weight pigs and neonates. The goal of this study was to determine the infectious dose of a post-2015 SVA isolate in neonatal pigs and compare its infectivity to the 2011 SVA isolate. A 2018 SVA isolate (SVA/KS/2018) was serially 10-fold diluted to create inoculums ranging from 10^5.5 to 10^0.5 TCID50/ml. Four individually housed animals were inoculated orally for each dilution. Detection of SVA RNA in serum and swabs, as well as virus neutralizing antibodies were used to classify infection status of animals. The minimum infectious dose for SVA/KS/2018 in neonates was 316 TCID50/ml (10^2.5 TCID50/ml). This value is similar to the infectious dose determined for SVA/CAN/2011, thus providing evidence that the increase in SVA detections was not due to increases in infectivity of contemporary isolates. Pigs inoculated with higher doses of SVA/KS/2018 developed diarrhea and increased mortality; however, pathogenic bacteria were isolated from gastrointestinal tract of these animals, which may have contributed to disease development. Additional work is needed to further characterize the role of SVA in neonatal mortality.