The lact of antiviral effect of (polyinosinic acid): (polycytidylic acid) when attached to insoluble supports.

A local antiviral effect can be observed when (poly rI)-(poly rC), bound to Visking discs by u.v. irradiation, is incubated with monolayers of human foreskin fibroblast cells. Radioactive labelling of cytosine residues in (poly rI)-(poly rC) with -125I, has provided a much more sensitive method for determining the fate of the insoluble (poly rI)-(poly rC) than has been available hitherto. The antiviral effect is not related to the amount of (poly rI)-(POLY RC) present on the insoluble support but rather to the amount of polynucleotide lost from the support during incubation. Treatment of (poly rI)-(poly rC) which had been bound to cyanogen bromide-activated Sepharose with eigher dilute alkali or pancreatic ribonuclease released virtually all the polynucleotide. A small amount of (poly rI)-(poly rC) is released from the insoluble matrix in the presence of serum-free Minimum Eagle's Medium.