Flow cytometric evaluation of anti-herpes drugs.

A rapid means of screening drugs for toxicity and anti-herpes simplex virus activity was developed based on the flow cytometric detection of HSV induced changes in cellular DNA content. Subconfluent monolayers of human diploid fibroblasts (HEL 299) were assayed for DNA content with propidium iodide 24 h after infection with HSV-1 (multiplicity of infection 1-10) and treatment with the drug to be tested. Infection was detected by a broadening of the normal diploid and tetraploid peaks and presence of greater than 4-n DNA staining. Inhibition of viral DNA synthesis and maintenance of the normal growth pattern of control cells was indication of antiviral activity. Toxicity of the compound was indicated by the loss of S phase and tetraploid cell populations. Using this assay, we evaluated the activities of one experimental and two established antiviral agents.