Enhancement of the anti-herpetic effect of trichosanthin by acyclovir and interferon

Trichosanthin (TCS) is a type I ribosome-inactivating protein that has a wi de range of pharmacological activities. The present study investigated the effectiveness of TCS on herpes simplex virus (HSV-1). The anti-viral activi ty and toxicity of TCS on Vero cells were measured. Results showed that the ED50, TD50 and the therapeutic indices were 38.5, 416.5 and 10.9 mug/ mi, respectively. Anti-viral activity of TCS was substantially potentiated when it was used in conjunction with other anti-viral agents. The ED50 of TCS w as reduced 125-fold by acyclovir at a concentration of 0.001 mug/ml, which was practically devoid of significant anti-viral activity. Similarly, the E D50 of TCS was reduced 100-fold by interferon-alpha 2a at a concentration o f 100 IU/ ml. In conclusion, TCS is effective against HSV-1 and other antiv iral agents such as acyclovir or interferon can potentiate its action subst antially. (C) 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.