DIMERIZATION OF RUBELLA-VIRUS CAPSID PROTEIN IS NOT REQUIRED FOR VIRUS PARTICLE FORMATION

Rubella virus (RV) virions contain, in addition to the RNA genome, a c apsid protein (C) and two envelope glycoproteins (E1 and E2). The C pr otein in isolated virions has been reported to be a disulfide-linked d imer (C2). There are two cysteine residues (Cys-152 and Cys-196) withi n the C protein. To define the role of disulfide-linked C2 dimer in vi rion formation, site-directed mutagenesis was used to alter the Cys-15 2 residue to serine. The association of mutant C protein with envelope glycoproteins was examined by transient expression of the cDNAs in CO S cells. Mutation at the Cys-152 residue completely abolished the form ation of C2 dimer. However, C2 dimerization does not appear to be impo rtant for the assembly of RV structural proteins into virus-like parti cles. (C) 1996 Academic Press, Inc.