Abstract
Purified Penicillium stoloniferum viruses PsV-F and PsV-S both possess virus-associated RNA polymerase activity. The PsV-F polymerase was dependent upon GTP, ATP and magnesium chloride. It was not activated by Triton X-100. No DNA synthesis was observed when deoxyribonucleoside triphosphates were substituted for RNA precursors. The RNA reaction product for both viruses remained associated with the virus in sedimentation and electrophoresis and was resistant to digestion by pancreatic ribonuclease both before and after extraction from the virus. Extracted PsV-F RNA reaction product co-electrophoresed with parental double-stranded RNA.