Variation in innate immune responses to porcine epidemic diarrhea virus infection in piglets at different ages.

Porcine epidemic diarrhea virus (PEDV) poses a significant threat to pigs, with piglets under seven days old facing a mortality rate of up to 100 %. This study aimed to explore the maturation of the immune system in piglets across different age groups and their corresponding immune responses to PEDV infection. Real-time quantitative PCR was employed to assess the relative mRNA expression of inflammation-related factors in infected pigs compared to non-infected counterparts at varying ages. Additionally, flow cytometry was utilized to analyze the relative counts of CD4+ and CD8+ T cells, as well as CD21+ B cells, in peripheral blood, spleen, mesenteric lymph nodes, and Peyer's patches of piglets at different developmental stages. Our findings revealed a notable increase in IFN-α and IFN-γ, a decrease in TNF-α, and elevated expression of IL-1β, IL-6, IL-10, and IL-17 following PEDV infection. Furthermore, the numbers of CD4+ and CD8+ T cells, along with CD21+ B cells, exhibited a gradual rise with the advancement of piglets' age. Overall, our study underscores the progressive enhancement of piglets' resistance to PEDV infection as their immune system matures over time.