Transmissible Gastroenteritis Virus Infection Up-Regulates FcRn Expression via Nucleocapsid Protein and Secretion of TGF-ß in Porcine Intestinal Epithelial Cells

Qian, Shaoju; Gao, Zitong; Cao, Rui; Yang, Kang; Cui, Yijie; Li, Shaowen; Meng, Xianrong; He, Qigai; Li, Zili

The recombinant TGEV N protein were prepared using a baculovirus/insect cell expression system as previously described (Chen et al., 2017) . IPEC-J2 cells were added (0, 10, 20, 50, 100 or 200 ng/mL) recombinant TGEV N protein in medium and its FcRn expression detected by RT-qPCR and Western blot. IgG transport was performed as previously described methods (Guo et al., 2016a) . Transepithelial electrical resistance (TEER) was measured with planar electrodes (World Precision Instruments). IPEC-J2 cells were grown on 0.4-µm pore size transwell filter inserts (Corning Costar, United States) to form a monolayer exhibiting TEER > 1000 /cm 2 about 6-7 days. Monolayers were stimulated with recombinant TGEV N protein (100 ng/mL) for 12 h. Thereafter, Biotin-IgG (200 µg/mL) were applied to the basolateral or apical DMEM medium and incubated for 3 h at 37 • C. Meanwhile, the opposite chamber was incubated in DMEM medium. Three hours later, samples were collected in which apically and basolaterally directed IgG transports were conducted. Subsequently, the bidirectional transport (apical-to-basolateral or basolateral-to-apical) of IgG were measured by Western blot and avidin blot analysis.