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Three commercial monoclonal antibody-based enzyme immunoassays (Herpchek, IDEIA HSV and SureCell HSV) for detection of herpes simplex virus antigen were compared with isolation of virus in cell cultures. A total of 51 culture positive and 49 culture negative consecutively collected specimens that had been stored at -70 degrees C for a period of up to ten months were used in the study. Herpchek, IDEIA HSV and SureCell HSV assays gave a sensitivity of 88.2%, 82.4% and 47.1% respectively, and a specificity of 95.9%, 93.9% and 83.7% respectively compared to cell culture. A blocking antibody test showed that two culture negative specimens contained herpes simplex virus-specific antigens. If these two specimens were considered to be true positive, Herpchek, IDEIA HSV and SureCell HSV assays had a sensitivity of 88.7%, 83.0% and 47.2%, and a specificity of 100%, 97.9% and 85.1% respectively. The positive predictive value (using the resolved sample results) for Herpchek, IDEIA HSV and SureCell HSV was 100%, 97.8% and 78.1% respectively, and the negative predictive value 88.7%, 83.6% and 58.8% respectively. These results demonstrated that Herpchek and IDEIA HSV are sensitive and highly specific assays. Results could be obtained in less than five hours after receipt of specimens. SureCell HSV gave results in 15 minutes, but both the sensitivity and specificity were too low for this test to be considered as a substitute for culture.

Two new astrovirus assays, a rapid biotin-avidin enzyme immunoassay (EIA) and RNA probe hybridization, were developed and compared with an established astrovirus assay, an indirect EIA, and immune electron microscopy. Sensitivity and specificity were evaluated by using a screening panel of 22 astrovirus-positive and 305 astrovirus-negative fecal specimens. The biotin-avidin assay was equivalent in performance to the reference indirect assay, and both could detect about 10 ng of viral protein. Although the probe was more sensitive than either EIA and could detect higher dilutions of virus in tissue culture and stool specimens, it did not detect more astrovirus-positive fecal specimens. Of the 22 astrovirus-positive specimens detected by the EIAs, 20 were confirmed by immune electron microscopy with hyperimmune rabbit antiserum. To determine the usefulness of EIAs for large epidemiologic studies, EIAs were used to screen 1,289 stool specimens from three studies of children with and without diarrhea. Astrovirus was detected in 3.5% of specimens from children with diarrhea and 1.9% of specimens from those without diarrhea. Our results indicate that the biotin-avidin EIA is an efficient, sensitive, and specific method for routinely screening large numbers of fecal samples and that its application in epidemiologic studies may yield higher rates of astrovirus infection than have been found previously by other methods.

A direct solid-phase enzyme-linked immunoassay for rapid detection and typing of influenza virus was developed utilizing antibodies immobilized by covalent linkage to nylon beads. Covalent linkage of antibody to nylon was accomplished by treatment of partially hydrolyzed nylon with glutaraldehyde. For comparison to conventional enzyme-linked immunosorbent assays (ELISA), IgG fractions were adsorbed to polystyrene beads. Influenza type-specific immunoglobulins coupled to nylon beads were used in an enzyme-linked immunoassay to identify influenza A/USSR/77(H1N1), and A/Texas/75 (H3N2). In titrations of viral antigen, antibody coupled to nylon beads detected 1.9 X 10(4) plaque-forming units (PFU) per assay, whereas 2.2 X 10(5) PFU were required in assays utilizing antibody adsorbed to polystyrene beads. Use of fluorogenic or radioactive substrates for alkaline phosphatase-labeled antibodies increased the sensitivity for virus detection 10-fold with this enzyme, but were only slightly more sensitive than chromogenic substrates with peroxidase-labeled antibody.

Cotton swabs were used to collect two specimens each from 416 patients (206 males, 210 females) attending a sexually transmitted disease clinic. The first swab was transported in Specimen Storage Reagent and extracted in Specimen Dilution Buffer for enzyme immunoassay by Chlamydiazyme (Abbott Laboratories); the second swab was extracted into 2SP and inoculated into McCoy cell cultures. In the first phase of the study (215 patients: 111 males, 114 females) enzyme immunoassay results were positive (optical density greater than or equal to 0.1) in 30 of 35 instances in which Chlamydia trachomatis was isolated (sensitivity, 86%). Of 18 false-positive enzyme immunoassay results, 15 (83%) were cervical swabs (specificity, 90%). In a phase II study, using a modified Chlamydiazyme kit, 201 patients were tested (95 males, 106 females). Of 41 chlamydial isolates, 8 were not detected by the Chlamydiazyme test (sensitivity, 81%). Only three positive Chlamydiazyme test results could not be confirmed by culture (specificity, 98%). Overall, Chlamydiazyme assay provided a rapid (4 h), sensitive, and specific assay for the detection of chlamydial antigens.

A quantitative enzyme-linked immunosorbent assay was used for identification of selected enteroviruses: poliovirus type 1, echovirus type 6, coxsackievirus A type 9, and coxsackievirus B types 1 through 6. Partially purified viral antigens or virus-specific antibodies were adsorbed to polystyrene spectrophotometer cuvettes, which permitted the assays to be reported and compared in terms of enzyme units specifically reacting. Both the adsorbed antigen and the adsorbed antibody methods were approximately equal in terms of sensitivity and specificity of reaction. By use [14C]leucine-labeled enteroviruses, the amount of virus that bound to the plastics used was shown to be dependent on the purity of the virus preparation used, but it was higher than the amount that was bound by plastics coated with viral antibody. Diluents which contained 0.15% (vol/vol) Tween 20 and 2.0% (wt/vol) bovine serum albumin in phosphate-buffered saline, pH 7.2, were found to be the most effective in inhibiting nonspecific adsorption of immunoreagents. However, the presence of these inhibitors in phosphate-buffered saline solutions also caused desorption of virus or viral antibody during immunoassays; the amount of virus desorption varied with the type of preparation used, and antibody desorption was dependent on the concentration of antibody initially used for adsorption. For specific identification of a given enterovirus type by the enzyme-linked immunosorbent assay method used, approximately 10(5) plaque-forming units of virus per assay tube were required.