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 FcRn protein has been well known to transport IgG bidirectionally in polarized epithelial cells. Therefore, we hypothesized TGEV N protein could alter the role of IgG transcytosis epithelial cells and constructed the transwell system to mimic the porcine intestinal microenvironment using IPEC-J2 cells ( Figure 6D ). The polarized monolayers (TEER > 1000 /cm 2 ) were stimulated with recombinant TGEV N protein (100 ng/mL) for 12 h. Then, porcine biotin-IgG was added to the apical or basolateral surface of a IPEC-J2 cell monolayer, after 3 h at 37 • C we assessed the IgG transported to the opposite basolateral or apical chamber, respectively. The IgG H chain was detected in medium by Western blot (Figure 6D , lane 1). Importantly, IgG transport was enhanced 1.3-fold in the apical to basolateral (Figure 6D , lane 3) direction or 1.8fold in the basolateral to apical (Figure 6D , lane 5) direction by TGEV N in comparison to the mock-treated monolayer ( Figure 6D, lanes 2 and 4) .