Comparing Immunity Elicited by Feedback and Titered Viral Inoculation against PEDV in Swine

Porcine Epidemic Diarrhea Virus (PEDV) can infect pigs of any age, but the disease severity varies significantly, particularly affecting neonatal piglets due to their immature immune system. Various vaccination strategies have been questioned for their efficacy, especially since outbreaks have occurred even on vaccinated farms. Recent suggestions indicate that exposure to the virus may enhance the effectiveness of inactivated vaccines, highlighting the potential benefits of using attenuated viruses to generate immunity in sows without prior exposure. This study aimed to evaluate the humoral and cytokine responses in pregnant sows and their piglets after inoculation of affected piglet intestinal contents and a virus isolated. We measured immune parameters such as IL-12, IL-22, IgG, and IgA, as well as neutralizing antibodies in serum, colostrum, and milk. Notably, higher titers of neutralizing antibodies were found in sows immunized with the viral inoculum, while IL-12 and IL-22 levels showed no significant differences. Additionally, we assessed productive parameters like total piglets born, weaning mortality, average birth weight, and stillborn rates. The results indicated that sows treated with affected piglet intestinal contents had higher mortality (48.31%) and stillborn rates (20.96%) compared to those receiving the isolated virus (30.02% and 10.44%, respectively). These findings suggest that using an isolated virus can offer a safe, long-lasting, and specific immune response, underscoring the importance of thorough analysis of both systemic and mucosal immune responses against PEDV.