Retention of nonlinear viral DNA during herpes simplex virus latency in vitro.

We investigated the state of the herpes simplex virus type 2 (HSV-2) genome during latency in vitro. Latent DNA was present in the cell nucleus in a nonlinear configuration. The joint fragment was represented at approximately double the molar concentration of fragments from unique regions, indicating that genome termini had fused. The HSV-2 genome copy number was estimated to be between 1.5 and 8, with a mean value of 4.5 per latently infected cell. Nonlinear HSV DNA can therefore exist during latency both in vivo and in vitro.