Patent ID: 7811812

Claim:
A eukaryotic layered vector initiation system, comprising: a 5′ promoter sequence capable of initiating in vivo the 5′ synthesis of alphavirus RNA from cDNA, a sequence which initiates transcription of alphavirus RNA following the 5′ promoter, a nucleic acid molecule which operably encodes all four alphaviral nonstructural proteins, an alphavirus RNA polymerase recognition site, and a 3′ polyadenylation site, wherein said nucleic acid molecule encodes at least one altered alphaviral nonstructural protein (nsP) which, when operatively incorporated into a recombinant alphavirus particle, has a reduced level of vector-specific RNA synthesis as compared to wild-type and the same or greater level of protein encoded by RNA transcribed from the viral junction region promoter as compared to wild-type recombinant alphavirus particle.