Expression and purification of Ag-SA fusion proteins. A Amino acid sequence of SA-RSV fusion protein. B Purified SA-RSV fusion protein (15 µg) eluted from the 2-Iminobiotin Agarose column was separated in Tris-Tricine SDS-PAGE gel and the proteins were visualized by Coomassie blue staining. 1—SA-V-srcA; 2—SA-V-srcB; 3—SA-ENVoep; 4—SA-ENVly; 5—SA-GAG; 6—SA-POL. All samples were heated to 100 °C for tetramer dissociation. Only the denatured monomeric forms of antigen streptavidin fusion proteins are visualized on the gel.