Expression of the rubella virus structural proteins by an infectious Sindbis virus vector

To assess the potential of an infectious Sindbis virus vector (dsSIN) as a eukaryotic expression vector, dsSIN recombinants which contain each of the rubella virus (RUB) structural proteins (C, E2, and E1) individually were constructed. Expression of the RUB proteins by each dsSIN recombinant was robust and processing was similar to that observed when these proteins were expressed using other vectors. The C and E2 recombinants, each of which contains a cassette of less than 1,000 nts, were stable through low multiplicity amplification; however, the E1 recombinant, which contains a 1700 nt cassette, was not. Therefore, use of the E1 recombinant is restricted to stock derived from the original transfection. The replication rate of dsSIN and the C and E2 recombinants was similar, however, the replication rate of the E1 recombinant was slower. No phenotypic mixing of any of the RUB proteins in recombinant dsSIN virions could be detected.