Infection, Interaction and the Expression of Virulence by Defined Strains of Semliki Forest Virus

Abstract
The small-plaque effect induced by exposure of herpes simplex virus to u.v. light was investigated. New results are presented showing that the effect was due to a delay of multiplication of virus in the cells initiating plaques. The delay occurred after entry of virus into the cell and before the replication of virus. The ultimate cause of the delay was probably the formation of thymine dimers, since the small-plaque effect was reversed by photoreactivation in avian cells. Evidence was obtained for co-operative reactivation and host-cell reactivation in infected BHK cells but neither of these phenomena could be related to the small-plaque effect.