Generation and protective efficacy of a cold-adapted attenuated genotype 2b porcine epidemic diarrhea virus

Won, Hokeun; Lee, Dong-Uk; Jang, Guehwan; Noh, Yun-Hee; Lee, Seung-Chul; Choi, Hwan-Won; Yoon, In-Joong; Yoo, Han Sang; Lee, Changhee

Considering that neutralizing antibodies are associated with protective immunity in neonates against PEDV infection, we tested serum and colostrum samples collected from sows and their neonatal piglets for the presence of anti-PEDV antibodies by an SN assay. As shown in Fig. 9A , all sows developed anti-PEDV neutralizing antibodies after the live prime vaccination. Thereafter, the neutralizing antibody titers in sera of vaccinated sows gradually increased, likely resulting from a homologous boost. All the three sows maintained high neutralizing antibody titers for 2 weeks post-farrowing. Consistent to the results from the serum samples, the neutralizing antibody level was significantly high in the colostrum of vaccinated sows (Fig. 9B) . Furthermore, the nursing piglets from each litter in group 1 had pre-challenge neutralizing antibody levels similar to those of their own dam and retained antibodies up to 7 DPI, indicating the protective effect of lactogenic immunity passively acquired from vaccinated sows (Fig. 9C) . Clinical significance score Log TCID /mL (groups 2 and 3). Taken together, these data demonstrate that oral vaccination with the coldadapted live attenuated virus efficiently elicits potent antibody responses in sows, which are subsequently transferred to the offspring via their milk to provide protection against PEDV.