Fig. 3.

Antibody responses to the rS1 protein in rabbits. (A) Binding of rabbit antisera directed against rS1. Cell lysates prepared from Vero cells infected with SM98-1 and the purified rS1 proteins were resolved in a 4–12 % gradient Bis-Tris gel using the indicated concentrations and electrotransferred onto a nitrocellulose membrane. The blot was reacted with rabbit serum collected at the second boost (top panel), anti-human IgG antibody (middle panel), or mouse MAb specific for PEDV S (bottom panel). (B) Neutralization of PEDV by rabbit antisera raised against rS1. Rabbit sera collected before starting immunization and at each boost and pig hyperimmune serum directed against PEDV SM98-1 were subjected to the virus neutralization assay against SM98-1 and visualized using crystal violet staining. Only one neutralization assay result for rabbit antiserum collected at necropsy is shown in the left panel. The names of the respective sera are labeled at the top, and antibody titers are indicated on the left