The presence of an RNA-dependent RNA polymerase was demonstrated in purified infectious pancreatic necrosis virus (IPNV). The enzyme was active without any pretreatment of the virus. Optimum activity was shown at 30 °C, pH 8 and in the presence of 6 m-magnesium ions. Approx. 50% of the polymerase product remained associated with the dsRNA template of the virions. The remainder was found as extravirion ssRNA broken down to 5S to 7S fragments by virus-associated RNase(s). Although the addition of bentonite considerably reduced the amount of RNA synthesized, it protected the ssRNA product from degradation. This, in turn, permitted the synthesis of small amounts of ssRNA, which when analysed by sucrose gradient centrifugation or polyacrylamide gel electrophoresis behaved identically to the 24S single-stranded virus mRNA produced in infected cells. The virion polymerase was not stimulated by -adenosyl--methionine or the addition of cellular or capped reovirus ssRNA. Several other modifications of the assay system were tried in an attempt to increase 24S RNA synthesis, but with little success. When [H]uridine-labelled virus was used in the polymerase reaction, some labelled 24S ssRNA was obtained, indicating that transcription may proceed by a semi-conservative (displacement) mechanism.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error