Spectrum of sensitivity of acyclovir of herpes simplex virus clinical isolates.

HSV-1 and HSV-2 clinical isolates were tested for their in vitro sensitivity to acyclovir. The median ID50 for 32 genital HSV-2 isolates was 0.215 micrograms/ml and this was not significantly higher than a median value of 0.125 micrograms/ml for 28 oral HSV-1 isolates (p = 0.08). A wider range of ID50s was observed with the HSV-2 isolates compared with the HSV-1 isolates. The concentration of drug required to inhibit virus replication by 90 and 99 percent was approximately 10- and 100-fold greater than that producing 50 percent inhibition.