Suential appearance of both swine vesicular disease virus and Gxsadaevirus ES antigens in a pig kidney cell line was stw3i by irnmunofluorescence and electron microscopy. The replication cycle of each virus was apoxirnaely 3-4 h. Viral antigens were demonstrable in the cytoplasm 2 h after inctulation. A coinjeci mass of fluorescence was seen when cells showerl cytopathogenic effect at 3.5 h, After 3 k a few viral jrtides, seen by electron microscopy, were in the cytoplasm, Morphological changes of cells occurred at the same time. Qrtoplasmic cryslline arrays of virus were first detected at? li.