CLIA VZV IgG

Varicella zoster virus (VZV, HHV-3) belongs to the Herpetoviridae family. The virus causes chickenpox, varicella (primary infection) and shingles, herpes zoster (reactivation). Primary VZV infection occurs mainly in childhood, and it is transmitted by means of droplet infection. Up to 90% of humans without specific antibodies can be infected during close contact with an infected person. The symptoms include fever, malaise and skin itching preceding the development of characteristic exanthema. The disease usually terminates without any lasting effects. Primary infection in adolescents and adults can be generally more severe with serious complications (e.g. encephalitis, pneumonia and hepatitis) especially in immunocompromised patients. The virus can be transmitted via placenta to the foetus; this can lead to severe congenital defects. Maternal infection of seronegative female (i.e. without specific antibodies) in late gestation presents serious risk for a newborn.
As a member of the Herpetoviridae family, the virus may persist latently in the organism and can be reactivated subsequently (reduced immunity) producing a disease known as shingles.
Diagnosis of the disease is based on clinical manifestation, epidemiological anamnesis and laboratory tests. The most widespread serological method used for the detection of specific IgA, IgM and IgG (avidity) antibodies to VZV in laboratory diagnosis of the infection is ELISA. Specific IgG antibodies have anamnestic character and serve for patient immunological status assignment.
Antibodies of IgM and IgA class are a sign of an active infection (primary infection and reactivation) and disappear during convalescence. In some cases, they can persist for several months.
Specific IgG antibodies mostly remain in reduced levels throughout the entire life of the infected person. The method of IgG avidity detection is used for discrimination between primary infection and past infection or reactivation.