A specific inhibitor of polyoma virus in infected rat and hamster cells and in transformed clones of hamster cells.

Abstract

SUMMARY Extracts of polyoma virus infected hamster cells made 8 to 10 hr after infection stimulated polyoma virus production in permissive mouse cells, whereas extracts made from 12 hr onwards inhibited virus production. No such inhibitor was found in mouse embryo cells within 22 hr of infection under the same conditions. A genetic study of a mouse-hamster-hybrid cell line showed that non-permissiveness was not a dominant trait and seemed to depend on the inhibitor which could be expressed only in non-permissive cell lines. A specific inhibitor was found also in clones of hamster cells transformed by polyoma virus in vitro and in a clone of transformed hamster cells derived from a tumour induced by virus in vivo. This inhibitor did not reduce DNA synthesis or replication of non-infected permissive mouse cells. It reduced the number of infective centres and the yield of infective virus, infective DNA and of the polyoma DNA component I.