Diagnosis of varicella-zoster virus (VZV) infection by using FITC-labeled monoclonal antibodies

Anti-varicella zoster virus (VZV) mouse monoclonal antibodies conjugated with fluorescein isothiocyanate were evaluated for their usefulness as a practical diagnostic tool in the clinical field by examining cells infected with isolated herpes viruses and 431 clinical samples. The kit stained clearly the cells infected with 14 isolated VZV strains without cross reaction to 15 isolated herpes simplex virus type-1 strains (HSV-1) and 14 type-2 (HSV-2) strains. In clinical specimens, viral antigens of VZV were detected in 92/105 (87.6%) cases of varicella and in 176/190 (92.6%) cases of herpes zoster. Specific fluorescence of VZV was also observed in 5 out of 96 cases diagnosed as HSV infections, although these samples had no specific reaction to HSV when tested by the commercially available diagnostic kit. In 24 cases which could not be clinically diagnosed as herpes zoster or herpes simplex, the VZV antigen was demonstrated in 9 cases. All 109 VZV-positive cases in virus isolation by culture were also judged VZV-antigen positive by the kit, while all 69 HSV-positive cases in virus isolation were VZV-antigen negative. Furthermore, the VZV antigen was detected by the kit in 53/60 clinical diagnoses of varicella or herpes zoster without successful virus isolation. These results clearly indicate the usefulness of the kit as a practical VZV diagnostic reagent, especially in terms of specific sensitivity and easy technical manipulation.