The present invention relates to viral vectors which are biologically contained, self-replicating and capable of the non-nuclear chromosomal transformation of a host. The viral vectors may contain a heterologous coding sequence adjacent a viral promoter. The invention further relates to viruses containing the viral vectors which are transmissible, i.e. infective. The invention also relates to production cells which are capable of producing the viruses or parts thereof. Host cells are infected by the viruses of the invention. A process for the production of a desired product by growing the infected hosts is also within the scope of the present invention.
