Genome organization of the herpesviruses: minireview

Fundamentally, the members of the herpesvirus family can be divided into six genome structure types designated by the letters A-F. Most of the viruses relevant to animal diseases belong to the D or E type. Whereas the biological function of the different DNA structures is so far unknown, studies on HSV genome structures indicate a rolling-circle mechanism as a mode of virus replication. Furthermore, the terminal repetitive segments seem to be involved in cleavage/packaging mechanisms and probably in the integration process of virus into the host genome. In the well-studied D and E type viruses a great number of genes are colinearly arranged and are homologous regarding their sequences. Thus genes encoding alpha-proteins map at least in part within the reiterated sequences, whereas beta- and gamma-polypeptide genes are largely located within the unique sequences of the long and short components.