Prescribed RNA Particle Vaccine Against Porcine Sapovirus Enhances Virus-Neutralizing Antibody Titers in Colostrum and Milk.

Confirmed porcine sapovirus (PoSaV) infection in young pigs have been increasing in swine farms; however, studies evaluating strategies to control PoSaV under field conditions remain scarce. In a commercial farm, one group of pregnant sows and gilts (n = 13 sows and 2 gilts) were vaccinated intramuscularly twice with an RNA particle vaccine containing the PoSaV VP1 gene, while the other group served as non-vaccinated controls. We evaluated the viral neutralizing (VN) antibodies in colostrum and milk collected at 1, 2, and 3 weeks post-farrowing. Fecal PoSaV shedding in 2-week- and 3-week-old piglets from both groups was assessed by reverse transcription-quantitative PCR. Body weight was measured at birth and 3 weeks of age when piglets were weaned. The vaccination group had higher VN antibody titers than the non-vaccinated group in colostrum and milk samples, with significance for colostrum and milk samples at 1-week post-farrowing. The colostrum and milk samples from both groups contained high VN antibody titers (>103.5 VNT50/mL) and remained high for at least three weeks, suggesting previous exposure to PoSaV. Corresponding to these high VN titers, all piglets were negative for PoSaV and had similar body weights at birth and 3 weeks of age. Future vaccination-challenge studies are warranted to confirm the efficacy of this vaccine.