ABSTRACT
Herpesviruses are large, enveloped, morphologically complex DNA viruses. Members of the herpesvirus family are widely distributed in nature, and isolates have been found in mammals, birds, fish, reptiles, and amphibians as well as certain invertebrate species. The initial step in the replication cycle of all viruses is attachment to a cellular receptor. Herpesvirus penetration into the host cell is rapid and appears to involve direct fusion of the virion envelope with the plasma membrane. After penetration, herpesvirus virions are transported via the cytoskeleton to the vicinity of the nucleus. Herpesvirus genes are expressed during productive infection by a cascade mechanism. Herpesvirus DNA synthesis takes place in the nucleus. The capsids of herpesviruses are assembled in the nucleus. Infection of herpesviruses can result in several outcomes including cytolysis or death, latency, or transformation. Herpesviruses, like most other cytolytic viruses, actively terminate host macromolecular synthesis early after infection. Several herpesviruses have been implicated in the induction of human cancers.
