Reactivity of varicella-zoster virus subunit antigens in enzyme-linked immunosorbent assay to sera from varicella,zoster, and herpes simplex virus infections

Serological responses to varicella-zoster virus (VZV) subunit antigens, such as capsid, envelope, and soluble (S) antigens, in patients with VZV and herpes simplex virus (HSV) infections were studied by comparing with responses to virion (V) antigens using an enzyme-linked immunosorbent assay (ELISA). S antigen, prepared by concentrating supernatant of VZV or HSV type 1 (HSV-1)-infected cell culture fluid, reacted strongly to sera from patients with secondary infection but reacted poorly to those from patients with a primary infection of VZV or HSV. Antibody titers to VZV-S antigen persisted for a long period in patients with VZV infections. Patients infected with VZV showed antibody increase to HSV-1, when tested by complement fixation or complement-enhanced neutralization test, in cases with a history of prior HSV infection. However, such a cross-reaction was only observed to a minor extent in ELISA test using S antigen. S antigen reaction was stronger in secondary infections in tests with various subunit antigens. Almost no cross-reactivity was observed in an immunoblotting test with S antigen. Differentiation between infections with either varicella or zoster or HSV can be made by comparison of antibody responses to V and S antigens.