“…Development of efficient in vitro run-off transcription systems based on cloned bacteriophage promoters and purified Escherichia coli or bacteriophage RNA polymerase has led to the production of biologically active RNA transcripts from eDNA clones of a number of plant and animal viruses (Ahlquist et al, 1984;Mitzutani & Colonno, 1985;Loesch-Fries et al, 1985;Dasmahapatra et al, 1986;Dawson et al, 1986;van der Werf et al, 1986;Meshi et al, 1986;Langereis et al, 1986;Rice et al, 1987). Such transcripts represent well-defined and stable inocula which are, furthermore, easily manipulated at the eDNA level by recombinant eDNA techniques.…”