FIG. 7.

TGEV morphogenesis in ST cells. This diagram is a summary of the experimental results on TGEV morphogenesis obtained in the present work and in a previous study by Risco et al. (37). The immature and mature morphologies of TGEV viral particles are shown at the bottom. The monensin blockade at a pre-Golgi level is also indicated. Reactivity with MAbs refers to immunolabeling experiments with thin sections of infected cells. Mature virions contain dense cores with polygonal contours, which have been observed in ultrathin sections of freeze-substituted samples (37). They suggest an icosahedral symmetry for these cores, which needs to be confirmed by high-resolution structural studies.