Figure 2.

Cascade of herpesvirus gene expression. Herpesvirus genes are expressed in a coordinated temporal cascade: immediate early (α), early (β). There are two subclasses of late gene expression that have been defined, although they are expressed concurrently: leaky-late (γ1) is not dependent on DNA synthesis, and true late (γ2) is dependent on DNA synthesis. Packaging of RNAs in the virion allows immediate expression upon virus entry in the absence of transcription, and thus adds an additional element in the highly regulated cascade of gene expression of herpesviruses.