FIG. 1.

Coexpression of multiple SV5 proteins in transfected cells leads to budding of particles. 293T cells were infected with rSV5 (A), transfected with plasmid encoding SV5 M protein (B), transfected with plasmids encoding SV5 M and SV5 HN proteins (C), or transfected with plasmids encoding SV5 M, SV5 HN, and SV5 NP proteins (D). At 24 h p.i. or p.t., cells were radiolabeled for 16 h with [³⁵S]Promix, followed by collection of both cells and culture media. Culture media was clarified by low-speed centrifugation, centrifuged through 35% sucrose cushions, and separated on sucrose flotation gradients into six equal fractions as described in Materials and Methods. Cells were disrupted by Dounce homogenization and centrifuged at low speed to remove nuclei and debris. SV5 proteins M, HN, and NP were immunoprecipitated from samples as described in Materials and Methods, and polypeptides were analyzed by SDS-PAGE on 10% gels. Lane 1, cell lysate; lanes 2 to 7, fractions from flotation gradient, with lane 2 representing proteins found at the top of the gradient and lane 7 representing proteins found at the bottom of the gradient.