2.1 Cells, virus, bacteria and expression vector
Vero cells (ATCC CCL-81) were cultured in Dulbecco’s modified Eagle’s medium (DMEM; Life Technologies, NY, USA) supplemented with 10% fetal bovine serum (FBS; Life Technologies), 100 U/ml penicillin G and 100 μg/ml streptomycin. A G1 PEDV CV777 vaccine strain was kindly provided by Dr. Enjuanes, Department of Molecular and Cell Biology, Campus Universidad Autonoma de Madrid, Madrid, Spain. A G2 PEDV strain CH/ZMDZY/11 was isolated from 3-day-old piglets suffering from watery diarrhea and dehydration by our laboratory (Wang et al., 2013). These piglets were generated by CV777vaccince-immunized sows. pET-28a (+) plasmid was purchased from Novagen (WI, USA).Escherichia coli DH5α and BL21 (DE3) were used for cloning experiments and as a heterologous expression host respectively.