1. In partial fulfillment of the requirements for the Ph. D. degree at Cornell University (S. S. Lai).
2. Present address: Taiwan Provincial Research Institute for Animal Health, Tansui. Taipei, Taiwan, Republic of China.
3. Present address; Department of Anatomy, University of Virginia Medical Center, Cahrlot-tesville, VA., U. S. A. 22908.
4. Plum Island Animal Disease Center USDA, SEA, AR, Greenport NY,USA., 11944.
Sequential appearance of both swine vesicular disease virus and Coxs-ackievirus BS antigens in a pig kidney cell line was studied by immuno-fluorescence and electron microscopy. The replication cycle of each virus was approximately 3-4 h. Viral antigens were demonstrable in the ytoplasm 2 h after inoculation. A compact mass of fluorescence was seen when cells showed cytopathogenic effect at 5.5 b. After 3 h, a few viral particles, seen by electron microscopy, were in the cytoplasm. Morphological changes of cells occurred at the same time. Cytoplasmic crystalline arrays of Yirus were first detected at 7 h.