Method for Measuring Antiviral Susceptibility of Herpes Simplex Virus Type 1 and Establishment of Resistant Strain

Objective To develop the method for measuring antiviral susceptibility and to establish an acyclovir-resistant herpes simplex virus type 1(HSV-1). Methods Baby hamster kidney cells were inoculated with HSV-1,and acyclovir(ACV) was added to the medium in various concentrations.After 72 hours' incubation,plaques were counted and the 50% inhibiting concentration(IC50) was calculated.HSV-1 was incubated in the presence of ACV for 9 passages.The IC50 of ACV was determined after the 3rd,6th and 9th passages. Results The IC50 of ACV to HSV-1 SM44 was 0.7 μg/ml.In the presence of ACV,emergence of drug resistance was observed after the 3rd passage;the IC50 of ACV after the 3rd,6th and 9th passages was 7.2 μg/ml,34.2 μg/ml,and 85.3 μg/ml,respectively. Conclusions Plaque reduction assay is an efficient method for determination of antiviral drug susceptibility of HSV and the establishment of ACV-resistant strain is essential for the study of resistance.