Sensitive solid-phase radioimmunoassay for detection of human immunoglobulin G antibodies to varicella-zoster virus

Abstract

A sensitive solid-phase radioimmunoassay [RIA] for detection of antibodies [Ab] to varicella-zoster virus (VZV) is described. The antigen [Ag] consisted of a sonically disrupted extract of VZV-infected human embryo cells. 125I-labeled rabbit anti-human immunoglobulin (Ig) G specific for the Fc portion of human IgG was used to detect human IgG bound to viral antigen. With this technique, 193 human sera were evaluated for their IgG Ab titer against VZV. Subjects included 62 healthy adults, 33 young children (12 healthy) and 49 patients. Titers obtained by the RIA were compared with those obtained by indirect fluorescence antibody staining of membrane Ag. The RIA technique described gave titers approximately 5 .times. 104 times higher than those shown by indirect fluorescence. It can be used for routine diagnosis, but is especially suited to determining immune status to VZV as defined by presence or absence of Ab to the virus, for epidemiological studies or for determining patients at risk who are exposed to the virus. No heterotypic titer rises to VZV were observed in sera with 4-fold or greater rises to Epstein-Barr virus or cytomegalovirus. Sera of 8 subjects with 4-fold or greater titer rises to herpes simplex virus reacted in various ways: in 6 cases no significant change occurred in titer to VZV; 1 had a significant decrease in titer by the radioimmunoassay; and 1 had a significant increase. Possible reasons for these titer changes are discussed.