Fig. 4

Overexpression of TfR1 enhances TGEV infection. a IPEC-J2, ST, and Caco-2 cells were transiently transfected with porcine TfR1. Cell lysates were analyzed for expression of TfR1 by western blotting using anti-TfR1 and GAPDH antibodies as probes. b and c IPEC-J2 cells that were overexpressing TfR1 were infected with Dylight 488-TGEV. After 1 h, TGEV invasion was detected by flow cytometry. d TfR1-overexpressing IPEC-J2 cells were infected with TGEV (MOI 5). After 1 h, TGEV-N mRNA levels were measured by RT-qPCR. e and f ST cells in which TfR1 was overexpressed were infected with TGEV for 24 h and lysates harvested for western blotting. Normal cells and cells transfected with expression vector alone served as controls. The TGEV-N to GAPDH ratio was normalized to control conditions. g-i TGEV-resistant Caco-2 cells that were expressing porcine TfR1 protein were challenged with TGEV (MOI 5). 24 h after infection, cell lysates were harvested for western blotting and culture supernatants were collected for viral plaque assays on ST cells. Plaques developed 2 days after infection. Normal cells and cells transfected with expression vector alone served as controls. The data shown are means ± SD from three independent experiments. (* 0.01 < p < 0.05, ** p < 0.01)