The Herpes Virus family is divided into 3 subfamilies:
 
  1. 1. Alphaherpesvirinae (i.e. EHV-1,4, BHV-1, Feline HV, Canine HV)
  2. 2.Betaherpesvirinae (i.e cyotmegalovirus, Muromegalovirus, and Roseolovirus)
  3. 3.Gammaherpesvirinae (i.e. Lymphocryptovirus and Rhadinovirus-malignant catarrhal fever)
 
 
 
 
Herpes Viruses
Electron micrograph of herpes virus particle
Herpesviradae
 
They are lipid enveloped viruses making them more susceptible to inactivation by disinfectants, as compared to viruses without an envelope. Without an envelope herpes viruses are not infective (11).
    
Herpesviradae viruses are composed of strucutal and non-structural proteins.
Structural proteins include:
1.    A protein fibrilar spool wrapped around DNA core
2.    A capsid composed of 12 pentameric and 150 hexameric capsomeres
3.    An amorphous protein layer in between the capsid and the envelope (tegument)
4.    An envelope with surface glycoproteins (spikes) (11)
 
The non-structural proteins are produced by the infected cell and are not present in the virion but are required to produce component of the virus. They are usually enzymes, such as thymine kinase (12).
 
To infect cells, the viral envelope attaches and fuses with the cell membrane via its surface spikes and the nucleocapsid migrates to the cell nucleus to replicate (11).
 
Transcription of the virus is divided into 3 groups:
    Immediate early
               Early
    Late transcription
 
Once the replication process is complete the structural proteins and the genome are assembled into icosahedral or helical virions and are then released. All herpes viruses isolated to date have this capacity(11)
 
A key feature of this family is the concept of viral latency; this means that the virus enters the cell but does not replicate. Instead its DNA sits in the nucleus in an extrachromasomal state, only expressing some of its genome and prevents cell suicide. It persists within the cell and can later be reactivated if the animal becomes stressed. The process of latency occurs in a variety of different cells specific to each type of herpes virus. For example latency of EHV can occur in sensory neurons and lymphoid cells (11)
 
There does not seem to be any common antigens among all members of herpesviradae family (11).