Western Blot Analysis
The 293F cell lysates infected recombinant or wild-typebaculoviruses (rB or wB) were resuspended with 120 μL 1 × SDS-PAGE loading buffer and boiled for 10 min before fractionated by electrophoresison 8% SDS-PAGE gels, and the resolved proteins were transferred onto PVDF membranes (Millipore, USA). After blocking with 5% skim milk, the membranes were probed with HRP-conjugated goat anti-Human Fc polyclonal antibody (1:2000; DingGuoShengWu, China) or primary antibodies [SADS-CoV-positive pig serum (1:200; Wen’s Foodstuffs Group Co., Ltd, China), or SADS-CoV-negative specific pathogen free (SPF) pig serum (1:200; Wen’s Foodstuffs Group Co., Ltd, China)], followed by incubation with HRP-conjugated goat anti-pig IgG (1:2000; Solarbio, China) secondary antibody. The blots were visualized using the ECL reagent according to the manufacturer’s instructions (GE Healthcare, UK).