Abstract
The standard method for measuring antiviral activity against VZV is PRA. This has several disadvantages: 1) Subjective endpoint; 2) time and labor intensity; and 3) inability to measure the drug-induced changes in plaque size. We improved upon this method as follows: human embryonic lung fibroblasts in microtiter plates were infected with VZV, antivirals were added, and 3 days later the monolayers were glutaraldehyde-fixed. VZV antigen w as quantitated in-situ using hyperimmune human globulin (VZIG) and peroxidase-conjugated goat anti-human IgG in a standard ELISA. Antigen representing 5 to 10 plaques could be detected. Dose-response curves for ELISA, PRA and infectious center assay were similar. When the activity of 4 antivirals (acycloyir, trifluorothymidine, adenine arabinoside and bromovinyldeoxyuridine) were compared by ELISA and PRA the ID 50's and the means of the coefficients of variation were lower by ELISA. An inoculum effect was also demonstrated for 3 of the 4 drugs tested. The in-situ ELISA was found to be superior to conventional PRA because the endpoint measurement was objective, multiple replicates were easily performed with little extra time or effort, and there was less variability. It is quicker when 3 or more samples must be tested, and is particularly suitable for viruses that produce plaques slowly.
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Berkowitz, F., Levin, M. 1064 Measurement of Antiviral Drugs Active Against Varicella Zoster Virus (VZV) Using ELISA Directly on Infected Cells: Superiority Over Plaque-Reduction Assay (PRA). Pediatr Res 19, 288 (1985). https://doi.org/10.1203/00006450-198504000-01094
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DOI: https://doi.org/10.1203/00006450-198504000-01094