I need to use viral antigen from enveloped virus as the coated antigen in ELISA. should I extract these viral antigen from the cell culture supernatant or use the entire cell culture? Any detergent? I tried to add NP-40 into the entire cell culture after freezing and thawing,yet failed. the color in ELISA is too weak. are there any better methods to tackle this problem? Hope u suggest relevant papers. thank u.