Herpes Virus Classification
The herpes virus classification includes eight types of viruses that can affect humans and several types that can affect animals. The herpes virus belongs to the Herpesviridae family, a large family of DNA viruses. These viruses are classified by the place where they are situated in latent state.
The HHV-1 type, also referred to as herpes simplex virus-1 or HSV-1 is classified in the Alpha subfamily and it can mostly be found in the mucoepithelial cells. It is transmitted through close contact. The HHV-2 or HSV-2 is a virus usually spread by close contact, especially sexual contact. It primarily affects the mucoepithelial cells and it is responsible for the sexually transmitted disease called genital herpes. The HHV-3 or varicella zoster virus (ZVZ) is the third type of virus from the subfamily Alpha, that also infects the mucoepithelial cells and it can be transmitted through respiratory routes and close contact. All these three types of viruses are located in the neuron during their latency period. The HHV-4 is a virus from the Gamma subfamily, also referred to as Epstein-Barr virus (EBV) or lymphocryptovirus. It mostly affects the B cells as well as the epithelial cells and the most common way of transmission is through saliva. In the latent state, EBV is located in the B lymphocytes. The HHV-5 or Cytomegalovirus (CMV) is located in the monocytes, lymphocytes and others cells and it spreads through blood transfusions, transplants, close contact or congenital. It primarily affects the monocytes, lymphocytes and epithelial cells. These types of virus along with the HHV-6 and HHV-7 viruses causing roseola infantum in children are part of the Beta subfamily and they affect that T cells. Types HHV-6 and HHV-7 are located in the T lymphocytes and other cells. The last type, HHV-8 or Kaposi’s sarcoma-associated herpesvirus are herpesviruses that affect the lymphocytes and some other cells and they are transmitted through exchange of body fluids. The location of these herpesviruses in their latent state is unknown.
The viruses from the Herpesviridae family, or the herpesviruses represent the second most common cause of the human viral diseases, after influenza virus and the cold viruses. Once a person contracted it, the virus may remain in a latent form in the body and reactivate over the years, thus once a person got infected the virus remains in the body for life. However, most of the people have antibodies to this kind of viruses, apart from the HHV-8 herpesvirus. The HSV-1 and HSV-2 types are also known as herpes simplex viruses which are contagious and cause a cathegory of diseases called herpes simplex. Some of the conditions they can cause are the oral herpes, herpes keratitis, genital herpes or HSV Meningitis. Currently there are no cures known for these infections even though there are treatments available that can reduce its spreading.
The herpes virus classification includes viruses that affect only humans but there are few other types of viruses from the same family that affect exclusively animals and these belong mostly to the Alphaherpesvirinae subfamily.