Structural maturation of the transmissible gastroenteritis coronavirus

During the life cycle of the transmissible gastroenteritis coronavirus (TGE V), two types of virus-related particles are detected in infected swine tes tis cells: large annular viruses and small dense viruses. We have studied t he relationships between these two types of particles. Immunoelectron micro scopy showed that they are closely related, since both large and small part icles reacted equally with polyclonal and monoclonal antibodies specific fo r TGEV proteins. Monensin, a drug that selectively affects the Golgi comple x, caused an accumulation of large annular viral particles in perinuclear e lements of the endoplasmic reticulum-Golgi intermediate compartment. A part ial reversion of the monensin blockade was obtained in both the absence and presence of cycloheximide, a drug that prevented the formation of new vira l particles. After removal of monensin, the Golgi complex recovered its per inuclear location, and a decrease in the number of perinuclear large viral particles was observed. The release of small dense viral particles into sec retory vesicles and the extracellular medium was also observed, as was a pa rtial recovery of infectivity in culture supernatants, Small viral particle s started to be seen between the third and the fourth Golgi cisternae of no rmally infected cells. All of these data strongly indicate that the large a nnular particles are the immature precursors of the small dense viruses, wh ich are the infectious TGEV virions. The immature viral particles need to r each a particular location at the trans side of the Golgi stack to complete their morphological maturation.