Nucleocapsid and Envelope Protein of Semliki Forest Virus as Affected by Canavanine

Department of Virology, University of Helsinki, Finland Cytoplasmic nucleocapsids of Semliki Forest virus were formed in BHK21 cells treated with canavanine under such conditions that virus RNA synthesis continued but no infectious virus was released. On the other hand, envelope protein synthesis was strongly inhibited. The canavanine nucleocapsids formed sedimented at 140s and contained 42s virus RNA and a protein indistinguishable from the normal protein by polyacrylamide gel electrophoresis. The canavanine nucleocapsids were not released from the cells. Received 11 October 1971; accepted 16 December 1971.