Early induction of DNA single-stranded breaks in cells infected by herpes simplex virus type 1.

In cells infected with herpesviruses a series of host-cell nuclear changes can be observed in a temporal sequence, such changes include chromosome aberrations. The precise mechanism by which virus infection produces chromosome damage is not known. Previous studies have revealed modifications in the properties of chromatin from infected cells, but such modifications are not due to extensive breakdown of host DNA or alteration of the nucleosomal structure in bulk host chromatin. We have adapted and modified a fluorescence enhancement assay for DNA damage in order to study the effects of herpes simplex virus type 1 infection on the integrity of the host-cell DNA. Here it is reported that HSV-1 induces a significant number of single-stranded breaks in the host-cell DNA at early hours post-infection. Such breaks seem not to be directly related to the major breakdown of host-cell DNA seen at later times post-infection.