The present invention provides a gene expression system comprising: a) a self-replicating
expression vector of flavivirus origin which includes the flavivirus 5
untranslated region (UTR), at least a portion of the 5 coding region for
flavivirus core protein, the nucleotide sequence coding for the flavivirus non-structural
proteins, and the complete or most of the 3-terminal sequence of the flavivrus
3UTR, required for self-replication of flavivirus genomic material, which
vector is adapted to receive at least a nucleotide sequence without disrupting
its replication capabilities; and b) at least a second vector that is capable of
expressing flavivirus structural protein(s) and any other proteins required for
packaging of the self-replicating expression vector into flavivirus viral particles
which vector is engineered to prevent recombination with the self-replicating vector
when in its presence.
