Figure 4.

Corona-spike formation on the envelope of the chimeric hPIV2/S vaccine vector

Upper panels: conventional electron microscopy of the vector-infected Vero/BC-F packaging cells that were fixed with paraformaldehyde and glutaraldehyde to observe the fine structure of the viral surface. Lower panels: immunoelectron microscopy of the cells of the same preparation as in the upper panels, except that paraformaldehyde with a much lower concentration of glutaraldehyde was used for fixation of the cells in order to retain the antigenicity. The virion of hPIV2 varies in size (average diameter is between 150 and 300 nm) and shape (Vainionpaa and Hyypia, 1994). Scale bars are shown in each panel.