Enzyme immunofiltration staining assay for immediate diagnosis of herpes simplex virus and varicella-zoster virus directly from clinical specimens

Abstract

A simple, sensitive, 30-min assay for the detection of herpes simplex virus (HSV) and varicella-zoster virus (VZV) antigens in clinical specimens is described. The assay utilizes a filter manifold, biotinylated monoclonal antibodies, streptavidin-horseradish peroxidase conjugate, and the substrate aminoethylcarbazole. The method stains infected cells and cell debris a bright red and is easily interpreted with a dissecting microscope. Reconstruction experiments indicated that as few as two virus-infected cells per swab could be detected. This was equivalent to an infectivity titer of 29 to 160 50% tissue culture infective doses per infected cell and 250 times more sensitive than an enzyme immunofiltration assay which detects a soluble reaction product. Clinical swab specimens collected from ocular, oral, skin, and genital lesions were cultured for virus, and the remaining cell debris was immobilized on glass fiber filters and stained for the presence of virus antigens. Of 71 HSV culture-positive specimens, 66 (93%) were positive for HSV antigens. All of nine VZV culture-positive specimens were positive for VZV antigens. Of 98 culture-negative specimens, 7 were positive for either HSV (n = 3) or VZV (n = 4) antigens.