PEDV infection in neonatal piglets through the nasal cavity is mediated by subepithelial CD3⁺ T cells

Porcine epidemic diarrhea virus (PEDV) primarily infects neonatal piglets causing catastrophic effects on the global pig farming industry. PEDV infects piglets through the nasal cavity, a process in which dendritic cells (DCs) play an important role. However, neonatal piglets have fewer nasal DCs. This study found that subepithelial CD3⁺ T cells mediated PEDV invasion through the nasal cavity in neonatal piglets. PEDV could replicate in the nasal epithelial cells (NECs) isolated from the nasal cavity of neonatal piglets. Infection of NECs with PEDV could induce antiviral and inflammatory cytokines at the late stage. The infected NECs mediated transfer of virus to CD3⁺ T cells distributed in the subepithelial of the nasal cavity via cell-to-cell contact. The infected CD3⁺ T cells could migrate to the intestine via blood circulation, causing intestinal infection in neonatal piglets. Thus, the findings of this study indicate the importance of CD3⁺T cells in the dissemination of PEDV from the nasal cavity to the intestinal mucosa in neonatal piglets.