Poxviruses as expression vectors.

Poxviruses are widely used for the cytoplasmic expression of recombinant genes in mammalian cells. Recent improvements allow high expression and simplify the integration of multiple foreign genes. Vaccinia virus mutants and other poxviruses that undergo abortive infection in mammalian cells are receiving special attention because of their diminished cytopathic effects and increased safety. New replicating and 'non-replicating' vectors, encoding the bacteriophage T7 RNA polymerase for transcription of recombinant genes, have been engineered.