Electron microscopic analysis of pseudovirion particle formation. (A) Pseudovirion particles produced by vCP205 in BSC-40 cells. Magnification, ×40,000. (B) Pseudovirion particles produced by vCP205. Magnification, ×33,000. (C) Representative view showing lack of particles formed by Myr− vCP205 in BSC-40 cells. Magnification, ×21,000. CP, canarypox particle. (D and E) Pseudovirion particle formation by vCP205 in murine myoblast C2C12 line. Magnification, ×40,000. (F) Representative micrograph showing lack of particle formation by Myr− vCP205 in C2C12 cells. Magnification, ×22,000. Bars represent 100 nm.