FIGURE 1.
(a) MCV VP1 and VP2 proteins expressed in 293TT cells self-assemble into virus-like particles (VLP). This panel shows protein staining of gradient fractions from cell lysates expressing MCV strain 339 VP1 and VP2 proteins compared with murine polyomavirus VP1 and VP2, which are known to coassemble into VLP (Supporting Fig. 1). Each lane was loaded with 2.5 μl of fraction material, electrophoresed on a polyacrylamide gel and stained with SYPRO Ruby protein stain. Murine polyomavirus and MCV VP1 and VP2 proteins coassemble into high molecular weight complexes (fractions 7–9) with histone-associated DNA, which is characteristic for VLP production. (b) DNA concentrations, representing VLP encapsidation of cellular and plasmid DNA fragments, peak in high molecular weight gradient fractions 7–9 for both MCV and murine polyomavirus VLP. (c) Transmission electron microscopy of MCV VLP at ×50,000 magnification shows characteristic polyomaviral icosahedral capsid structures. Bar represents 100 nm.