peptide-specific antibodies were bound to the surface of live, RV-infected MDCK cells at 4°C. MDCK cells were infected with RV SA11.4F at a MOI of 2 for 11 h and either surface biotinylated followed by precipitation with streptavidin agarose (lane 2) or reacted with rabbit affinity-purified anti-NSP4150-175 and biotin-conjugated anti-rabbit IgG, then similarly precipitated with streptavidin agarose (lane 4). Cell lysates and the precipitated surface proteins were examined by Western blot using mouse anti-NSP4114-135. Lanes 1 and 3 are the cell lysates from the streptavidin pull-down and antibody binding, respectively. Lanes 2 and 4 show the full-length NSP4 exposed on exofacial surfaces, and lanes 5 and 6 are uninfected controls.