Upregulation of IL-8 mRNAs and proteins during IBV and PEDV infection. (A) H1299 and Vero cells were infected with IBV and PEDV at MOI~2 or mock-treated with UV-inactivated viruses. Cell were harvested at the indicated time points and total RNA samples were extracted for RT-qPCR. The levels of IBV genomic RNA (IBV) and PEDV genomic RNA (PEDV), and the mRNA levels of IL-8 and IL-6 were determined by the ΔΔCt method using the GAPDH mRNA of the virus-infected 0 hpi sample for normalization. The experiment was repeated three times with similar results, and the result of one representative experiment is shown. (B) Vero and H1299 cells were infected with IBV at MOI~2 or mock-treated with UV-inactivated IBV. Cell lysates were harvested at the indicated time points and subjected to Western blot analysis using the indicated antibodies. Beta-actin was included as the loading control. Sizes of protein ladders, in kDa, are indicated on the left. The experiment was repeated three times with similar results, and the result of one representative experiment is shown. Asterisk (*) indicates the nonspecific band detected by the IL-8 antibody.