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Varicella zoster virus (VZV)
Introduction
- Varicella zoster virus (VZV) is a dermotropic and neurotropic virus that produces primary infection, usually in
childhood, which may reactivate in later life.
- VZV is known by many names, including chickenpox virus, varicella virus, zoster virus, and, human herpesvirus type 3 (HHV-3).
Structure
- VZV is closely related to the herpes simplex viruses (HSV), sharing much genome homology. The known envelope glycoproteins (gB, gC, gE, gH, gI, gK, gL) correspond with those in HSV; however, there is no equivalent of HSV gD. VZV also fails to produce the LAT (latency-associated transcripts) that play an important role in establishing HSV latency (herpes simplex virus). VZV virons are spherical and 180–200 nm in diameter. Their lipid envelope encloses the 100 nm nucleocapsid of 162 hexameric and pentameric capsomeres arranged in an icosahedral form. Its DNA is a single, linear, double-stranded molecule, 125,000 nt long. The capsid is surrounded by a number of loosely associated proteins known collectively as the tegument; many of these proteins play critical roles in initiating the process of virus reproduction in the infected cell. The tegument is in turn covered by a lipid envelope studded with glycoproteins that are displayed on the exterior of the virion, each approximately 8 nm long.
Epidemiology
Taxonomy
- Family : Herpesviridae
- Subfamily : Alphaherpesviridae
- Genus : Varicellovirus
Transmission
- VZV is spread by aerosol and direct contact.
Diseases
- Varicella-zoster virus (VZV) causes two distinct clinical entities: varicella (chickenpox) and herpes zoster (shingles).
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