Herpesviridae family is a distinct viral family that contains a wide variety of viruses that are distributed worldwide. Viruses in the Herpesviridae family infect humans, mammals and other vertebrates. There are three subfamilies that make up the Herpesviridae family, and they include: Alphaherpesvirinae, Betaherpesvirinae, and Gammaherpesvirinae. Simplexvirus (for example, herpes simplex virus) and Varicellovirus (for example, Varicella-zoster virus) are the two genera of Alphaherpesvirinaethat contain viruses that infect humans. In the Betaherpesvirinae subfamily, there are only two genera of viruses that infect humans; and these include: Cytomegalovirus (that contain cytomegalovirus) and Roseolovirus (that contain human herpes virus types 6 and 7). Gammaherpesvirinae family has two genera viz: Lymphocryptovirus (that contain Epstein-Barr virus) and Rhadinovirus (that contain human herpesvirus 8). Viruses in the Herpesviridae family include herpes simplex virus (HSV) type 1 and 2. Other viruses in this family include: Varicella-zoster virus (VZV) which is found in the Alphaherpesvirinae subfamily; cytomegalovirus (CMV) which is found in the Betaherpesvirinae family; and Epstein-Barr virus (EBV) which is found in the Gammaherpesvirinae subfamily.
HSV 1 and HSV 2 cause genital herpes and orolabial herpes in humans. Morphologically, the herpes viruses have a dsDNA genome, and they measure about 150 nm or 100-300 nm in diameter. Structurally, herpes viruses have an icosahedral shape. They are enveloped viruses. Herpes viruses replicate in the nucleus and they are released from their host cell through budding through the cytoplasmic membrane of the infected host cells. Typical examples of clinical diseases caused by viruses in the Herpesviridae family include: chickenpox (caused by VZV), Burkitt’s lymphoma (a tumour caused by EBV), fever blisters or cold sores (caused by HSV-1) and genital herpes (caused by HSV-2 and HSV-1) (Table 1).
Some viruses in the Herpesviridae family such as CMV are common among individuals with weakened immune system especially HIV/AIDS patients. Lesions or blisters on the penis (in males), vagina or cervix (in females) and blisters appearing on the lips and mouth regions of infected individuals are some of the clinical symptoms of the disease caused by viruses in the Herpesviridae family. Some of the route of transmission of herpes viruses and/or disease includes direct sexual contact with an infected individual, transmission through aerosols, and other body fluids such as saliva. Herpes simplex virus can also be transmitted from an infected mother to the unborn child congenitally. It is noteworthy that herpes viruses have the ability to establish a latent infection in their natural host; and thus the virus is capable of re-emerging in its virulence in the future in an asymptomatic host. Prophylaxis and antiviral therapy exist for the treatment of some human herpes virus infections.
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