A RAPID AND RELIABLE ASSAY FOR TESTING ACYCLOVIR SENSITIVITY OF CLINICAL HERPES-SIMPLEX VIRUS ISOLATES INDEPENDENT OF VIRUS DOSE AND READING TIME

The determination of acyclovir (ACV) sensitivity of clinical herpes si mplex virus (HSV) isolates was studied by means of a cytopathic effect (CPE) inhibitory assay (CIA). Medium of HSV-infected Vero cells was s upplemented with different ACV concentrations. The CPE was read quanti tatively by light microscopy. The inhibitory dose for 50% CPE reductio n (ID50) was calculated by applying 1(st) or 3(rd) degree regression l ines, and aspects of different methods for calculation are discussed. The CIA proved highly reproducible. Surprisingly, the obtained ACV-ID5 0 values were independent of reading time and virus dose used in the t est. In comparison to dye-uptake assay, CIA could be evaluated earlier . Therefore, CIA provides simple,rapid, and precise determination of A CV sensitivity of clinical HSV-isolates which can be achieved within 1 or 2 days after the virus has been isolated out of a clinical specime n.